LA BREA TAR PITS: DIRE WOLVES, MAMMOTHS, HORSE, BISON AND MORE

Smilodon Skull at La Brea Tar Pits

In the heart of Los Angeles, surrounded by traffic, office towers and people carrying coffees of improbable complexity, the Earth is still bubbling. 

Dark pools of natural asphalt rise through the ground at Hancock Park, methane breaks at the surface and the air carries the unmistakable scent of petroleum. 

Beneath the lawns and walkways lies one of the richest Late Pleistocene fossil deposits on Earth.

Mammoths are here. Dire wolves are here. Sabre-toothed cats, enormous bison, ancient horses, camels, ground sloths, coyotes, birds, beetles, seeds, pollen and the delicate bones of tiny rodents are all here. 

Not alive, mercifully, but preserved in extraordinary numbers beneath modern Los Angeles, where natural asphalt seeps have been trapping plants and animals for tens of thousands of years.

The La Brea Tar Pits do not record one terrible day. They contain the accumulated evidence of countless separate accidents repeated across millennia. One animal became trapped, another arrived to investigate and several more approached because the Ice Age had not yet developed adequate warning signage.

FIRST, THEY ARE NOT ACTUALLY TAR PITS

The substance at La Brea is more accurately called natural asphalt, asphaltum or bitumen. Tar is generally produced by heating organic materials such as wood or coal, while asphalt is a naturally occurring petroleum substance. The familiar name has nevertheless stuck, which seems appropriate under the circumstances.

There is also a pleasing redundancy in “La Brea Tar Pits.” La brea means “the tar” in Spanish, making the full name roughly “the Tar Tar Pits.” We could insist upon calling them the La Brea Asphalt Seeps, but that would deprive palaeontology of a perfectly good geological tongue-twister.

Beneath the Los Angeles Basin are thick, oil-rich marine deposits laid down millions of years ago. Petroleum migrated upward through faults and fractures until it reached the surface. There, lighter components evaporated or were degraded by microorganisms, leaving the heavier and remarkably sticky asphalt behind.

This material did not necessarily form the enormous open pools often depicted in paintings and museum dioramas. Asphalt could seep into shallow depressions and spread across the ground, sometimes hidden beneath water, dust, leaves or sediment. To an approaching animal, the surface may have looked like ordinary damp soil or a harmless watering place.

The mistake would become apparent with the first step.

THE MAKING OF A PREDATOR TRAP

An asphalt seep did not need to be deep enough to swallow a mammoth whole. It needed only to be sticky enough to hold a foot. Once a hoof sank into the asphalt, the animal’s attempts to pull free could trap another limb. Struggling pressed the feet deeper, spread asphalt across hair and skin and rapidly exhausted the victim.

Large herbivores such as bison, horses, camels, mammoths and ground sloths occasionally became immobilized in this way. Their distress calls and movements attracted predators and scavengers. 

A trapped bison represented a large meal that had already been thoughtfully restrained, and predators approached the opportunity with understandable enthusiasm and insufficient caution.

Dire wolves gathered. Sabre-toothed cats moved closer. Coyotes and scavenging birds arrived. Some fed from firmer ground, while others stepped onto the same deceptive surface and became trapped themselves.

This process is known as the predator-trap hypothesis, and it helps explain the remarkable abundance of carnivores in the La Brea deposits. One struggling herbivore could attract several predators and scavengers, producing a fossil assemblage in which carnivores greatly outnumber herbivores.

Roughly 70 to 80 per cent of the site’s larger mammal specimens are carnivores. That is almost the reverse of what we would expect in a living ecosystem, where herbivores generally outnumber large predators. The Natural History Museums of Los Angeles County notes that this carnivore-heavy composition distinguishes La Brea from most other fossil deposits.

This does not mean Ice Age Los Angeles was carpeted in dire wolves with the occasional bison squeezed between them. It means the asphalt seeps selectively trapped animals attracted to struggling prey. The deposit records not only which species lived in the region, but also how their behaviour influenced their likelihood of preservation.

The fossil record is rarely an impartial census. At La Brea, it is closer to a list of everyone who approached the buffet without first inspecting the floor.

DIRE WOLVES, SABRE-TOOTHED CATS AND ANCIENT COYOTES

Dire wolves were among the most frequently trapped large mammals. Known scientifically as Aenocyon dirus, they were heavily built canids that lived across the Americas during the Late Pleistocene. They had robust jaws and teeth suited to feeding on large prey, although, like living wolves, they probably scavenged when a meal presented itself.

Their abundance at La Brea may provide indirect evidence of social behaviour. If dire wolves hunted or scavenged in groups, one trapped herbivore might attract several pack members. A single incident could therefore add multiple wolves to the deposit. One meal, several hopeful carnivores and a deeply regrettable group decision.

The large collection allows researchers to study dire wolves as a population rather than as a scattering of isolated specimens. Individual animals can be compared for age, body size, tooth wear, injury and disease. Changes in anatomy and diet can also be tracked through time.

The most famous predator at La Brea is Smilodon fatalis, the sabre-toothed cat. If you have seen the skull and teeth of this kitty, you will agree the name is apt. 

A fun fact and wee aside, Canada's first Smilodon was found in a drawer in a museum by Dr. Rufus Churcher when he was poking about an old collection in Alberta. A wonderful storyteller with a keen eye, we owe that man a lot.

It was not a tiger, despite the enduring popularity of the name “sabre-toothed tiger.” Smilodon belonged to an extinct branch of the cat family and had a body built quite differently from that of modern lions or tigers.

It possessed enormous upper canine teeth, exceptionally powerful forelimbs, a deep chest and a relatively short tail. Its jaw could open extraordinarily wide, allowing those elongated canines to be used without colliding with the lower jaw. Rather than pursuing prey over long distances, Smilodon was likely an ambush predator. Its muscular forelimbs may have helped restrain large prey while it delivered a carefully positioned bite.

This was important because the famous canine teeth, though formidable, were not indestructible. They were effective weapons but poor candidates for being driven casually into struggling bone. Even the Ice Age’s most dramatic dental arrangement required responsible handling.

La Brea specimens preserve evidence of arthritis, fractures, tooth damage and healing. Some animals survived serious injuries long enough for their bones to repair. This has raised intriguing questions about whether sabre-toothed cats lived socially and whether impaired individuals may have received food or protection from others.

Healing proves survival, but it does not automatically prove social care. An injured animal might have scavenged, selected smaller prey or simply endured. We must distinguish what a bone demonstrates from what it merely suggests. Still, the injuries reveal that these cats had individual histories. They aged, suffered accidents, recovered and continued living in a landscape filled with large prey, competing carnivores and treacherously sticky patches of ground.

Coyotes, Canis latrans, also occur abundantly at La Brea, but unlike dire wolves and sabre-toothed cats, they survived the end-Pleistocene extinction. Their ecological flexibility may have given them an advantage. Coyotes can eat mammals, insects, fruit, carrion and an impressive assortment of whatever else becomes available. They can occupy deserts, grasslands, woodlands, agricultural areas and cities.

Large specialists often thrive when their preferred prey and habitats are stable, but they can struggle when ecosystems change rapidly. Coyotes appear to have regarded climatic upheaval, megafaunal extinction and the eventual construction of Los Angeles as challenges requiring only minor adjustments.

They still live in the city today.

MAMMOTHS, MASTODONS AND CAMELS IN CALIFORNIA

The herbivores preserved at La Brea include ancient bison, horses, camels, deer, pronghorn, mammoths and mastodons. Together, they reveal a Southern California landscape quite different from the one we know today.

Columbian mammoths, Mammuthus columbi, were enormous members of the elephant family. They possessed long, curving tusks and high-crowned ridged teeth suited to processing abrasive vegetation. Their diets varied across environments and could include both grasses and other plants.

American mastodons, Mammut americanum, were shorter and more heavily built, with molar teeth bearing rounded cusps. These teeth were better suited to crushing leaves, twigs and branches. Mammoths and mastodons were related, but they were not interchangeable shaggy elephants wandering through identical habitats.

Their teeth record the difference rather elegantly. Mammoth molars resemble enormous washboards. Mastodon molars carry prominent rounded cusps, which gave the animal its name: “mastodon” refers to the breast-like shape of the tooth projections. Palaeontology occasionally arrives at terminology by routes we might not choose today.

One of the site’s remarkable discoveries is a largely complete Columbian mammoth nicknamed Zed. His remains were uncovered in 2006 during the construction of an underground parking facility beside the Los Angeles County Museum of Art. Zed is a reminder that major palaeontological discoveries do not always require an expedition to a distant desert. Sometimes they require a construction crew, a parking proposal and someone sensible enough to stop digging.

Ancient camels also lived in Ice Age California. The western camel, Camelops hesternus, was a large North American member of the camel family. This seems surprising only because we associate camels with Africa and Asia today. Camels actually evolved in North America and lived on the continent for tens of millions of years. Some migrated into Eurasia across Beringia, while others moved into South America and eventually gave rise to llamas, alpacas, guanacos and vicuñas.

The disappearance of camels from North America is the unusual part. Their presence at La Brea was perfectly ordinary at the time.

PROJECT 23: PALAEONTOLOGY BY WOODEN BOX

When construction near the Tar Pits encountered fossil deposits in 2006, excavating every specimen individually would have delayed work for an extremely long time. Instead, palaeontologists and engineers built large wooden crates around 23 fossil-bearing deposits. The blocks were lifted intact and moved to La Brea Tar Pits, where they could be excavated under controlled conditions.

The operation became known as Project 23.

Along with the boxed deposits came 327 buckets of fossil-rich sediment. The material contains large mammal bones, but also turtles, fish, snails, insects, seeds, leaves, small vertebrates and other remains essential to reconstructing the wider ecosystem. The museum’s Project 23 overview notes that researchers will be processing this enormous collection for years.

Project 23 demonstrates an important reality of modern palaeontology: fossil discovery frequently occurs during construction. Roads, foundations, mines and parking structures expose geological layers that would otherwise remain hidden. When scientific teams and developers work together, these unexpected discoveries can be recovered without sacrificing either the fossils or the project.

It also proves that if you place 23 enormous crates of asphalt-soaked Ice Age sediment in front of palaeontologists, they will be happily occupied for the foreseeable future.

THE TINY FOSSILS THAT RECONSTRUCT A LANDSCAPE

Mammoths and sabre-toothed cats attract attention, but some of La Brea’s most informative fossils are less than a centimetre long.

The asphalt and surrounding sediments preserve insects, spiders, seeds, leaves, pollen, molluscs, fish, frogs, lizards, bird bones, rodent teeth and tiny skeletal fragments. These remains are recovered from the excavated sediment, or matrix, which is carefully processed and examined under microscopes.

Staff and volunteers sort through it grain by grain. It is patient, meticulous work requiring steady hands and an ability to become sincerely delighted by something resembling a burnt sesame seed.

Microfossils allow researchers to reconstruct details that large mammal bones cannot provide. Pollen and seeds identify ancient vegetation. Beetles and other insects can indicate temperature, moisture and local habitat. Frogs and salamanders reveal the presence of freshwater or damp environments. Rodents can be sensitive indicators of particular ecological conditions.

The La Brea Fossil Lab emphasizes the importance of these small fossils for understanding environmental and climatic change during the Late Pleistocene.

Large mammals tell us who occupied the landscape. Microfossils tell us what the landscape was like.

Ice Age Los Angeles was not buried beneath a continental glacier. The region was generally cooler and wetter than it is today, with streams, grasslands, scrub and woodlands of oak and juniper. Mammoths, bison, horses and camels moved through these habitats while predators followed them.

It was recognizably Southern California, but with more water, fewer freeways and a substantial increase in large mammals capable of overturning your vehicle.

HOW ASPHALT PRESERVED THE FOSSILS

When animals became trapped, their bodies decayed and their bones sank into asphalt-rich sediment. Petroleum entered the pores of the bones, staining them dark brown or black and helping protect them from weathering and some forms of microbial destruction.

The asphalt also preserved delicate biological materials rarely retained at other fossil sites. These include bone collagen, plant cellulose and chitin from insect exoskeletons. Such materials can be used for radiocarbon dating, stable-isotope analysis and other forms of biochemical research.

La Brea is an exceptional Late Quaternary fossil deposit created by petroleum seepage over approximately the past 60,000 years. Its geoheritage profile notes that the site preserves millions of fossils representing hundreds of species.

The preservative, however, is also a contaminant. Petroleum contains ancient carbon that can distort radiocarbon dates. Researchers must therefore remove the asphalt carefully and isolate original organic material from the fossil.

The substance that protected the bone for tens of thousands of years must be persuaded to leave before the bone will surrender its age.

La Brea likes to keep its secrets sticky.

DATING EXTINCTION

Specialized methods for removing petroleum contamination have allowed researchers to obtain increasingly reliable radiocarbon dates from La Brea specimens.

In a major study of Ice Age extinction, scientists produced approximately 170 new dates for coyotes, horses, camels, bison, sabre-toothed cats, giant ground sloths, American lions and dire wolves. These dates helped establish when each species disappeared from Southern California.

The results suggest that the regional extinction did not occur in one sudden event. Large mammals vanished as the climate warmed, drought intensified, vegetation changed and fire activity increased. Human populations were also becoming established in the region, adding another ecological influence.

These pressures interacted. A warming climate altered habitats. Drought dried vegetation. Fire transformed plant communities. Large herbivores lost forage, while predators lost prey. Species able to change their diets or behaviour had an advantage over those dependent on a narrower range of conditions.

The Natural History Museums of Los Angeles County describes La Brea as an exceptional record because some species are represented by hundreds or thousands of individuals. This makes it possible to study not simply their existence, but their decline and disappearance through time.

The Tar Pits preserve extinct animals, but more importantly, they preserve the approach of extinction.

GIANT GROUND SLOTHS AND OTHER UNEXPECTED RESIDENTS

Among the more impressive herbivores at La Brea was Harlan’s ground sloth, Paramylodon harlani. Unlike modern tree sloths, it lived on the ground and possessed a heavily built body, powerful limbs and long claws. Small bony plates called osteoderms were embedded within its skin, providing an additional layer of protection.

It may have used its claws to pull down vegetation, dig for roots or defend itself from predators. When standing partly upright and supported by its tail, it could reach vegetation well above the ground.

Modern sloths give the impression that they would apologize for occupying your chair. Giant ground sloths look as though they might take the chair, the dining table and the adjacent shrubbery.

The deposits also preserve American lions, short-faced bears, pronghorn, peccaries and native horses, alongside reptiles, amphibians and an extraordinary diversity of birds. Asphalt is particularly effective at preserving delicate hollow bird bones, which are easily destroyed at other sites. As a result, La Brea holds one of the world’s largest fossil bird collections.

The birds are not merely background characters. Eagles, vultures, owls, ravens, waterbirds and songbirds occupied different parts of the ecosystem. Their remains help reconstruct habitats and food webs, while changes in bird communities can reflect broader environmental change.

ASPHALT AS A CULTURAL RESOURCE

The La Brea landscape has a human history as well as a palaeontological one. Indigenous peoples knew and used natural asphalt long before scientific excavation or commercial extraction began.

Tongva and Chumash peoples used asphalt to waterproof baskets and canoes, improve tools and create decorative objects. The material was also traded across the region. Educational material from La Brea Tar Pits recognizes this long history of Indigenous knowledge and use.

The asphalt was therefore not simply a dangerous geological substance. In knowledgeable hands, it was a valuable technology.

Commercial mining and extraction followed much later. Asphalt from Rancho La Brea was used for roofing and road construction before the area became protected for its fossils.

The site cannot be understood only as a trap for Ice Age animals. It is a cultural landscape where people observed, understood and worked with a distinctive natural resource for thousands of years.

A COLLECTION OF MILLIONS

Scientific excavation at La Brea began in earnest in 1913, although fossil bones had been encountered earlier. More than 100 excavations have since been conducted.

At the collection’s last comprehensive census in 1992, it already contained more than 3.5 million specimens. That number includes everything from large mammal bones to insects, seeds and tiny vertebrate remains. The La Brea collections include more than 60 mammal species, along with birds, reptiles, amphibians, fishes, molluscs, arthropods and plants.

The site remains scientifically active. Asphalt continues to seep, methane continues to bubble and fossil-bearing deposits continue to be excavated. La Brea is not a completed quarry whose discoveries are safely finished and catalogued. It is an active research site in the middle of a major city.

Beneath the lawns, streets and buildings, the Ice Age is still present.

A FOSSIL RECORD WITH A TRAP BUILT INTO IT

La Brea offers a particularly useful lesson in how fossil deposits must be interpreted.

The asphalt did not collect organisms fairly. Large animals were more likely to become immobilized than very small ones. Carnivores and scavengers were disproportionately drawn to trapped herbivores. Birds, insects and plants entered the deposits through different pathways. Individual seeps may also have accumulated remains over hundreds or thousands of years rather than during a single event.

We cannot simply count the fossils and assume the resulting proportions mirror the living community. More dire wolf bones do not prove that dire wolves vastly outnumbered bison across the landscape. 

They may demonstrate that dire wolves were social, attracted to distressed prey and willing to step onto suspicious ground when meat was involved.

Understanding how remains accumulated is the work of taphonomy—the study of everything that happens between an organism’s death and its discovery as a fossil.

La Brea is both a window and a filter. It reveals the Ice Age, but it reveals it through asphalt.

THE STICKY ARCHIVE OF LOS ANGELES

There is something wonderfully improbable about La Brea. A city famous for reinvention sits above an archive of extinction. Traffic moves along Wilshire Boulevard while methane rises from petroleum formed by ancient marine organisms. 

People walk through Hancock Park above the remains of mammoths, dire wolves and sabre-toothed cats. The past is not somewhere else. It is directly beneath the picnic blanket. Oh, how I would love to dig a little but they frown on that sort of thing in parks. Shame. Yes, we can see wonderful examples in the museum, but it is sheer pleasure to excavate yourself.

The Tar Pits preserve death in overwhelming abundance, but their scientific value lies in what they reveal about life. Their fossils tell us what animals ate, how they were injured, which plants grew around them and how ecosystems responded as the climate changed. Tiny seeds document shifting vegetation. Tooth enamel preserves chemical evidence of diet. Bones record growth, disease and survival.

Even the strange abundance of carnivores tells a story. One trapped herbivore could attract several predators. One tempting meal could produce fossils studied tens of thousands of years later.

The asphalt waited. The animals approached, encouraged by hunger and betrayed by optimism.

And the Earth kept every receipt.

Image Credit: Asset id: 2278428163. Prehistoric bones and the skull of saber-tooth cat, Smilodon fatalis, in a block of resin at the La Brea Tar Pits, Los Angeles, California

SVALBARD: ICE, SNOW AND ICHTHYOSAURS

Reindeer, Rangifer tarandus 

Ho Ho Ho. Ice, Snow, Reindeer & Ichthyosaurs — Svalbard is just what I imagine my version of Valhalla to be like, without all the mead, murder and mayhem. 

This Norwegian archipelago sits between mainland Norway and the North Pole. 

One of the world’s northernmost inhabited areas, it is known for its rugged, remote terrain of glaciers and frozen tundra sheltering polar bears, reindeer and Arctic fox. 

It is also known for reindeer. The lovelies you see here are all females as the males lose their antlers in the winter. So Rudolf and the rest of Santa's crew who pull his sleigh for him would have all been females as they are pictured with antlers. They are also shown flying across the sky, so the science gets a bit creative.

The Northern Lights or Nordlys are visible during winter, and summer brings the Midnight Sun — sunlight 24 hours a day. Norway or Norge is one of the very few locations where sunset merges into the sunrise, with no darkness in between, creating a soft, captivating twilight in which to view the world. 

The Botneheia Formation is made up of dark grey, laminated shales coarsening upwards to laminated siltstones and sandstones. South of the type area, the formation shows four coarsening-upward units. 

The formation is named for Botneheia Mountain, a mountain in Nordenskiöld Land at Spitsbergen, Svalbard. It has a height of 522 m.a.s.l., and is located south of Sassenfjorden, east of the valley of De Geerdalen. 

Svalbard, Norway

I was asked recently if folk head out in the torrential rain or ice and snow to fossil collect. I would generally say yes for those where the potential prize always outweighs the weather. For Svalbard, it is a resounding yes. 

You have to remove the snow cover — or ice if you are impatient or unlucky — to get to the outcrops here. It is well worth the effort. Beneath the icy cover, you find lovely ammonoids and bivalves. 

Tastier still, ichthyosaur remains are found here. The first Triassic ichthyosaurs from Svalbard were found in the early 20th century. Now there are quite a few Triassic and Jurassic ichthyosaur species from this archipelago.

Two ichthyosaur specimens have been recovered that are of particular interest. They comprise part of the trunk and the caudal vertebral column respectively. 

Some features, such as the very high and narrow caudal and posterior thoracic neural spines, the relatively elongate posterior thoracic vertebrae and the long and slender haemapophyses indicate that they probably represent a member of the family Toretocnemidae. 

Ichthyosaur Bones

Numerous ichthyosaur finds are known from the underlying Lower Triassic Vikinghøgda Formation and the overlying Middle to Upper Triassic Tschermakfjellet Formation, the new specimens help to close a huge gap in the fossil record of the Triassic ichthyosaurs from Svalbard. 

There is a resident research group working on the Triassic ichthyosaur fauna, the Spitsbergen Mesozoic Research Group. 

Lucky for them, they often find the fossil remains fully articulated — the bones having retained their spatial relationship to one another. 

Most of their finds are of the tail sections of primitive Triassic ichthyosaurs. In later ichthyosaurs, the tail vertebrae bend steeply downwards and have more of a fish-like look. 

In these primitive ancestors, the tail looks more eel-like — bending slightly so that the spines on the vertebrae form more of the tail. 

Maisch, Michael W. and Blomeier, Dierk published on these finds back in 2009: Neues Jahrbuch für Geologie und Paläontologie - Abhandlungen Band 254 Heft 3 (2009), p. 379 - 384. Nov 1, 2009.

Svalbard, Norway (Norge)

Svalbard was so remote that there were no Inuit or First Nation settlements. It is certainly possible an earlier people came through these islands, but they did not leave any trace of their travels. 

The first documented travellers to explore Spitsbergen arrived in 1795 as part of a hunting expedition. They included people from the arctic town of Hammerfest in Norway's far north. They were an excellent choice as they were used to barren, inhospitable lands and sailed to discover more. 

We know them as the Coast Sámi — a hearty, rugged people probably best known in history for their chieftain, Ottar. He left Hammerfest in the 9th century to visit then join King Alfred the Great's court in a newly forming England. 

Expeditions to the remote islands of Svalbard continued into the early 1800s and finally, a settlement was eked out of the cold landscape and slowly expanded to the rest of the islands. While today the islands are called Svalbard, I would have named them for the Norwegian word for remote — fjernkontroll.

Aristoptychites euglyphus and Daonella sp.

This marvellous block is filled with Aristoptychites (syn = Arctoptychites) euglyphus (Mojsisovics, 1886) and Daonella sp., oyster-like clams or bivalves from the Middle Triassic, Ladinian, rugged windswept outcrops at the top of the Daonella Shales, Botneheia Formation, Spitzbergen, Edgeøya and Barentsøya, eastern Svalbard, Norway. 

Daonella and Monotis are important species for our understanding of biostratigraphy in the Triassic and are useful as Index fossils. 

Index fossils are fossils used to define and identify geologic periods or faunal stages. To be truly useful, they need to have a short vertical range, wide geographic distribution and rapid evolutionary development.

Daonellids preferred soft, soupy substrates and we tend to find them in massive shell beds. Generally, if you find one, you find a whole bunch cemented together in coquina. The lovely block you see here is in the collections of the deeply awesome John Fam. 

Learning Languages

The Sámi languages (/ˈsɑːmi/ SAH-mee), Sami or Saami, are a group of Uralic languages spoken by the Sámi people in Northern Europe in parts of northern Finland, Norway, Sweden, and extreme northwestern Russia. Of the world's languages, I find them the most difficult for my mind and tongue to wrap around. The Uralic languages will be familiar to you as Hungarian (Magyar nyelv), Finnish and Estonian. 

Since my Sámi is terrible, I will share a few words of Norwegian that may come in handy if you visit Svalbard and have a hankering for their tasty fossils or fossiler. To say, ice, snow, reindeer and ichthyosaurs in Norwegian, you would say: is, snø, reinsdyr og ikthyosaurer. 

To say, "hello, where can I find fossils?" Use, "Hei, hvor kan jeg finne fossiler?" An expression you may not need but circumstances being what they are, "That is a big polar bear," is "Det er en stor isbjørn." A solid follow-up would be, "nice bear, run..." as "Fin bjørn, løp..." Good luck with that.

Wishing you and yours the very best of the holidays however you celebrate. 

LOWER LIAS LYTOCERAS

A superbly prepped and extremely rare Lytoceras (Suess, 1865) ammonite found as a green ammonite nodule by Matt Cape in the Lower Lias of Dorset. 

Lytoceras are rare in the Lower Lias of Dorset — apart from the Belemnite Stone horizon — so much so that Paul Davis, whose skilled prep work you see here, initially thought it might be a Becheiceras hidden within the large, lumpy nodule. 

One of the reasons these lovelies are rarely found from here is that they are a Mediterranean Tethyian genus. The fossil fauna we find in the United Kingdom are dominated by Boreal Tethyian genera. 

We do find Lytoceras sp. in the Luridum subzone of the Pliensbachian showing that there was an influx of species from the Mediterranean realm during this time. This is the first occurrence of a Lytoceras that he has ever seen in a green nodule and Paul's seen quite a few. 

This absolutely cracking specimen was found and is in the collections of the awesome Matt Cape. Matt recognized that whatever was hidden in the nodule would take skilled and careful preparation using air scribes. Indeed it did. It took more than five hours of time and skill to unveil the lovely museum-worthy specimen you see here. 

We find Lytoceras in more than 1,000 outcrops around the globe ranging from the Jurassic through to the Cretaceous, some 189.6 to 109.00 million years ago. Once this specimen is fully prepped with the nodule material cut or scraped away, you can see the detailed crinkly growth lines or riblets on the shell and none of the expected coarse ribbing. 

Lytoceras sp. Photo: Craig Chivers

If you imagine running your finger along these, you would be tracing the work of decades of growth of these cephalopods. 

While we cannot know their actual lifespans, but we can make a healthy guess. 

The nautilus, their closest living cousins live upwards of 20 years — gods be good — and less than three years if conditions are poor.

The flanges, projecting flat ribs or collars, develop at the edge of the mouth border on the animal's mantle as they grow each new chamber. 

Each delicate flange grows over the course of the ammonites life, marking various points in time and life stages as the ammonite grew. There is a large variation within Lytoceras with regards to flanges. They provide both ornamentation and strength to the shell to protect it from water pressure as they moved into deeper seas.

The concretion prior to prep

This distinctive genus with its evolute shells are found in the Cretaceous marine deposits of: 

Antarctica (5 collections), Austria (19), Colombia (1), the Czech Republic (3), Egypt (2), France (194), Greenland (16), Hungary (25), Italy (11), Madagascar (2), Mexico (1), Morocco (4), Mozambique (1), Poland (2), Portugal (1), Romania (1), the Russian Federation (2), Slovakia (3), South Africa (1), Spain (24), Tanzania (1), Trinidad and Tobago (1), Tunisia (25); and the United States of America (17: Alaska, California, North Carolina, Oregon).

We also find them in Jurassic marine outcrops in:

Austria (15), Canada (9: British Columbia), Chile (6), France (181), Germany (11), Greenland (1), Hungary (189), India (1), Indonesia (1), Iran (1), Italy (50), Japan (14), Kenya (2), Luxembourg (4), Madagascar (2), Mexico (1), Morocco (43), New Zealand (15), Portugal (1), Romania (5), the Russian Federation (1), Slovakia (1), Spain (6), Switzerland (2), Tunisia (11), Turkey (12), Turkmenistan (1), Ukraine (5), the United Kingdom (12), United States (11: Alaska, California) — in at least 977 known collections. 

References:

Sepkoski, Jack (2002). "A compendium of fossil marine animal genera (Cephalopoda entry)". Bulletins of American Paleontology. 363: 1–560. Archived from the original on 2008-05-07. Retrieved 2017-10-18.

Paleobiology Database - Lytoceras. 2017-10-19.

Systematic descriptions, Mesozoic Ammonoidea, by W.J Arkell, Bernhard Kummel, and C.W. Wright. 1957. Treatise on Invertebrate Paleontology, Part L. Geological Society of America and University of Kansas press.

FOSSIL HUNTRESS PODCAST: DEAD SEXY SCIENCE

Geeky goodness from the Fossil Huntress. If you love paleontology, you will love this stream. Dinosaurs, trilobites, ammonites—you'll find them all here!

Close your eyes & fly with me as we head out together to explore Earth's rich history written in her rock. Travel to extraordinary places, sacred sites & unearth mysteries millions of years old on the Fossil Huntress Podcast.

This stream is for those who share an enduring passion for our world's hidden treasures, its wild places & want to uncover her beauty stone by stone.

This is the story of the making of our Earth and the many wonderful creatures who have called it home.

Join in the exploration of the fascinating science of paleontology — that lens that examines ancient animals, plants & ecosystems from wee single-celled organisms to big & mighty dinosaurs. Save the stream to your favorites to listen while you drive, head out fossil collecting or snuggle in for the night!

​To listen now, visit: https://open.spotify.com/show/1hH1wpDFFIlYC9ZW5uTYVL

ANCIENT ARAGONITE: FOSSIL PEARLS

One of my favourite pairs of earrings are a simple set of pearls. I have worn them pretty much every day since 2016 when I received them as a gift. What is it about pearls that makes them so appealing? I am certainly not alone in this. 

A simple search will show you a vast array of pearls being used for their ornamental value in cultures from all over the world. I suppose the best answer to why they are appealing is just that they are. 

If you make your way to Paris, France and happen to visit the Louvre's Persian Gallery, do take a boo at one of the oldest pearl necklaces in existence — the Susa necklace. It hails from a 2,400-year-old tomb of long lost Syrian Queen. It is a showy piece with three rows of 72 pearls per strand strung upon a bronze wire. 

A queen who truly knew how to accessorize. 

I imagine her putting the final touches of her outfit together, donning the pearls and making an entrance to wow the elite of ancient Damascus. The workmanship is superb, intermixing pure gold to offset the lustre of the pearls. It is precious and ancient, crafted one to two hundred years before Christ. Perhaps a gift from an Egyptian Pharaoh or from one of the Sumerians, Eblaites, Akkadians, Assyrians, Hittites, Hurrians, Mitanni, Amorites or Babylonian dignitaries who sued for peace but brought war instead. 

Questions, good questions, but questions without answers. So, what can we say of pearls? We do know what they are and it is not glamorous. Pearls form in shelled molluscs when a wee bit of sand or some other irritant gets trapped inside the shell, injuring the flesh. As a defensive and self-healing tactic, the mollusc wraps it in layer upon layer of mother-of-pearl — that glorious shiny nacre that forms pearls. 

They come in all shapes and sizes from minute to a massive 32 kilograms or 70 pounds. While a wide variety of our mollusc friends respond to injury or irritation by coating the offending intruder with nacre, there are only a few who make the truly gem-y pearls. 

These are the marine pearl oysters, Pteriidae and a few freshwater mussels. Aside from Pteriidae and freshwater mussels, we sometimes find less gem-y pearls inside conchs, scallops, clams, abalone, giant clams and large marine gastropods.

Pearls are made up mostly of the carbonate mineral aragonite, a polymorphous mineral — the same chemical formula but different crystal structure — to calcite and vaterite, sometimes called mu-calcium carbonate. These polymorphous carbonates are a bit like Mexican food where it is the same ingredients mixed in different ways. Visually, they are easy to tell apart — vaterite has a hexagonal crystal system, calcite is trigonal and aragonite is orthorhombic.

As pearls fossilize, the aragonite usually gets replaced by calcite, though sometimes by vaterite or another mineral. When we are very lucky, that aragonite is preserved with its nacreous lustre — that shimmery mother-of-pearl we know and love.  

Molluscs have likely been making pearls since they first evolved 530 million years ago. The oldest known fossil pearls found to date, however, are 230-210 million years old. 

This was the time when our world's landmass was concentrated into the C-shaped supercontinent of Pangaea and the first dinosaurs were calling it home. In the giant ancient ocean of Panthalassa, ecosystems were recovering from the high carbon dioxide levels that fueled the Permian extinction. Death begets life. With 95% of marine life wiped out, new species evolved to fill each niche.  

While this is where we found the oldest pearl on record, I suspect we will one day find one much older and hopefully with its lovely great-great grandmother-of-pearl intact. 

MIDDENS AND WEST COAST OYSTERS: T'LOXT'LOX

One of the now rare species of oysters in the Pacific Northwest is the Olympia oyster, Ostrea lurida, (Carpenter, 1864).  

While rare today, these are British Columbia’s only native oyster. 

Had you been dining on their brethren in the 1800s or earlier, it would have been this species you were consuming. Middens from Port Hardy to California are built from Ostrea lurida.

These wonderful invertebrates bare their souls with every bite. Have they lived in cold water, deep beneath the sea, protected from the sun's rays and heat? Are they the rough and tumble beach denizens whose thick shells tell us of a life spent withstanding the relentless pounding of the sea? Is the oyster in your mouth thin and slimy having just done the nasty—spurred by the warming waters of Spring? 

Is this oyster a local or was it shipped to your current local and, if asked, would greet you with "Kon'nichiwa?" Not if the beauty on your plate is indeed Ostrea lurida. 

Oyster in Kwak'wala is t̕łox̱t̕łox̱

We have been cultivating, indeed maximizing the influx of invasive species to the cold waters of the Salish Sea for many years. 

But in the wild waters off the coast of British Columbia is the last natural abundant habitat of the tasty Ostrea lurida in the pristine waters of  Nootka Sound. 

The area is home to the Nuu-chah-nulth First Nations who have consumed this species boiled or steamed for thousands of years. Here these ancient oysters not only survive but thrive — building reefs and providing habitat for crab, anemones and small marine animals. 

Oysters are in the family Ostreidae — the true oysters. Their lineage evolved in the Early Triassic — 251 - 247 million years ago. 

In the Kwak̓wala language of the Kwakwaka'wakw, speakers of Kwak'wala, of the Pacific Northwest and my family, an oyster is known as t̕łox̱t̕łox̱. 

I am curious to learn if any of the Nuu-chah-nulth have a different word for an oyster. If you happen to know, I would be grateful to learn.

ASK THE FOSSIL HUNTRESS: WHAT IS A FOSSIL

Pick up a fossil and you are holding evidence of a life.

Not merely an old rock. Not an attractive geological paperweight. Not something the Earth made solely to tempt us into climbing unstable slopes in inappropriate footwear.

A fossil is a message from the past.

It may be a bone, tooth, shell or leaf. It may be the delicate impression of a feather, the tunnel left by a burrowing animal or the footprints of a creature that crossed a muddy shoreline hundreds of millions of years ago.

It may even be fossilized dung.

The fossil record has never been overly concerned with dignity.

Together, fossils preserve the history of life on Earth: its astonishing experiments, spectacular successes, evolutionary detours and occasional catastrophes. They introduce us to organisms no human ever saw alive and to ecosystems that vanished long before our own species appeared.

But what exactly qualifies as a fossil—and how can something as fleeting as a footprint survive for millions of years?

Let us begin at the beginning.

SO, WHAT IS A FOSSIL?

Dinosaur Footprints near Tumbler Ridge, BC

A fossil is naturally preserved evidence of past life. That definition is deliberately broad because life leaves evidence in many different ways.

A fossil can be part of an organism’s body, such as a bone, tooth, shell, leaf or piece of wood. It can also be a mark made by an organism while it was alive: a footprint, burrow, feeding trail, nest or bite mark.

The organism itself does not necessarily need to be present.

This is one of the most important things to understand about fossils. We often picture a magnificent dinosaur skeleton standing in a museum, every rib neatly arranged and every tooth poised for drama. Yet complete skeletons are extraordinarily rare. Most fossils are fragments: a single tooth, part of a shell, a scrap of leaf, one vertebra or a dark smudge of carbon in the rock.

Some fossils are so small that thousands could sit comfortably on the head of a pin. Others belong to animals that stretched longer than a city bus.

All of them are evidence.

We divide fossils into two major categories: body fossils and trace fossils. The distinction is simple, but it opens the door to an astonishing variety of preservation.

BODY FOSSILS: WHEN PART OF THE ORGANISM REMAINS

A body fossil preserves part of the organism itself—or a direct impression, mould or cast of its remains.

The most familiar body fossils include:

• Bones
• Teeth
• Shells
• Exoskeletons
• Scales
• Wood
• Leaves
• Seeds
• Pollen
• Spores

Cenoceras Fossilized Shell Material

Hard parts are much more likely to enter the fossil record because they resist decay longer than soft tissues. Teeth are especially durable. A vertebrate animal may lose and replace thousands of teeth during its lifetime, greatly improving the odds that at least a few will survive long enough to become fossils.

This is one reason isolated fossil teeth are much more common than complete fossil animals. Nature produces teeth generously and skeletons only once per customer.

Shells also have an excellent chance of preservation. Ancient seafloors could accumulate the remains of countless brachiopods, molluscs, corals and other marine organisms. Over time, those shells became part of the sediment and, eventually, part of the rock itself.

The most durable portions of an organism dominate the fossil record. According to the National Park Service overview of body fossils, bones, teeth, shells, mineralized plates and wood are preserved far more frequently than skin, organs, flowers or fruit.

This creates an immediate problem.

The fossil record is not a complete census of everything that ever lived. It has a built-in preference for organisms with hard parts, those living in places where burial could occur and those fortunate enough to die under favourable conditions.

A clam living on a muddy seafloor has a better chance of becoming a fossil than a soft-bodied creature living on a windswept mountain. This does not mean the mountain creature was less important. It was simply less likely to leave us its forwarding address. We find many more of the durable creatures than we do the squishy. 

TRACE FOSSILS: WHEN BEHAVIOUR BECOMES STONE

Theropod Track, Thailand

Trace fossils preserve evidence of what an organism did rather than the organism’s actual body.

They are also called ichnofossils, from the Greek word ichnos, meaning track or trace. Scientists who specialize in studying them are called ichnologists.

Trace fossils include:

• Footprints and trackways
• Burrows and tunnels
• Trails
• Resting impressions
• Nests
• Root traces
• Feeding marks
• Bite marks
• Borings in shells or wood
• Coprolites, or fossilized dung
• Regurgitated material
• Gastroliths associated with an animal

A body fossil can tell us that an organism existed. A trace fossil may reveal what it was doing.

A line of footprints can show whether an animal walked on two legs or four. The distance between prints can help researchers estimate speed. Several parallel trackways may suggest that animals moved together, although such interpretations must be made carefully.

A burrow can reveal how an animal moved through sediment, searched for food or protected itself. Bite marks can document interactions between predator and prey. A resting impression can preserve the outline of an animal settling momentarily onto a soft surface.

Trace fossils often remain in the substrate where the behaviour originally occurred. Unlike bones, which may be carried away by water, scavengers or gravity, a burrow generally records activity at that exact location.

This gives trace fossils an extraordinary quality. They preserve moments. An animal stepped here. A worm burrowed here. Something bit this shell.

A dinosaur crossed this stretch of wet sediment, placing one foot after another beneath a sky no human would ever see. The animal continued on. The moment passed. But the ground remembered.

YES, FOSSILIZED POO IS A REAL FOSSIL

Coprolites are fossilized faeces, and they are among some of our most personal treasures.

They vary enormously in size and appearance. Some resemble pellets, spirals or lumpy stones. Others are difficult to distinguish from ordinary rock without examining their shape, contents or chemical composition.

Coprolites can preserve:

• Bone fragments
• Fish scales
• Plant fibres
• Seeds
• Pollen
• Insect remains
• Parasite eggs
• Chemical evidence of diet

They can help researchers determine whether an animal ate meat, plants, insects, fish—or almost anything unfortunate enough to fit inside it.

The difficulty lies in identifying the producer. Unless a coprolite is found directly associated with a particular animal, assigning it to a species can be challenging. Size, shape, contents and geological context may narrow the possibilities, but we must resist the temptation to point dramatically at every ancient dropping and declare, “Tyrannosaurus!”

Not every large coprolite came from the most famous carnivore available.

Still, fossilized dung offers something bones alone cannot: evidence of a meal passing through an animal’s digestive system. Coprolites are trace fossils that can provide direct clues about ancient diets.

One creature’s private moment has become everyone’s scientific business. Deep time can be terribly indiscreet.

DOES A FOSSIL HAVE TO BE TURNED TO STONE?

No. “Fossil” describes evidence of past life, not one particular style of preservation.

Some fossils are petrified or mineralized. Others preserve original material. Fossils can occur as impressions, carbon films, moulds, casts or remains trapped in substances such as amber, tar or ice.

Let us look at a few possibilities.

Permineralized Fossils

Bones and wood contain microscopic spaces. After burial, mineral-rich water may move through the sediment and deposit minerals inside those spaces.

This process is called permineralization.

The original structure may remain while its pores become filled with minerals such as silica, calcite or iron compounds. The result is denser and heavier than the original material but can preserve remarkable internal detail.

Petrified wood is a beautiful example. Its tissues may become mineralized so precisely that growth rings and cellular structures remain visible.

Replacement Fossils

In some fossils, the original biological material dissolves and is gradually replaced by minerals. The new mineral preserves the form—and sometimes even the microscopic structure—of the original organism.

It is rather like replacing a building one brick at a time while somehow retaining its shape.

Moulds and Casts

Imagine a shell buried in sediment.

The sediment hardens around it, but the shell later dissolves, leaving an empty impression. This cavity is a mould. If minerals or sediment later fill that mould and harden, they create a cast: a three-dimensional replica of the original shell.

An internal mould can form when sediment fills the inside of a shell and hardens before the shell disappears. Such fossils are sometimes called steinkerns, a German term meaning “stone kernel.”

Nothing of the original shell may remain, yet its shape survives. The body is gone. The absence has become the fossil. 

Compression and Carbon Films

McAbee Fossil Plants

Plants and soft-bodied organisms may be buried and flattened beneath accumulating sediment. Pressure drives away liquids and gases, sometimes leaving a thin film rich in carbon.

These fossils can appear as dark, delicate outlines on the rock. Leaves may preserve their veins. 

Fish may retain the shapes of scales and fins. Soft-bodied animals can sometimes be recorded in astonishing detail.

They are the geological equivalent of silhouettes—life pressed into stone. Some of the lovely specimens we find at the Eocene McAbee Fossil Beds near Cache Creek, British Columbia, are a great example.

Amber Preservation

Amber begins as sticky resin produced by ancient trees. Small organisms such as insects, spiders, mites and fragments of plants can become trapped in the resin. As the resin is buried and chemically altered over time, it becomes amber.

Amber can preserve extraordinary detail: hairs, wings, compound eyes and delicate structures that would normally decay rapidly.

It can even preserve tiny moments of behaviour. Organisms have been found trapped while feeding, mating, carrying pollen or interacting with parasites.

Amber is not a perfect time capsule, however, and it has not provided usable dinosaur DNA. The mosquitoes of Jurassic Park remain unemployed. If you are looking for some superb examples of amber preservation, check out the collection of Harry Tabiner in the UK. He has a remarkable eye and enviable collection, which he shares online.

Ice, Dryness and Natural Tar 

Cold, arid or oxygen-poor conditions can dramatically slow decay. Mammoths preserved in frozen ground may retain hair, skin, muscle and stomach contents. Natural tar deposits can preserve vast collections of bones, although the remains themselves may be stained, altered or compressed.

These forms of preservation remind us that a fossil does not need to resemble a traditional stone skeleton. Fossilization is not a single recipe. It is a vast collection of unlikely outcomes.

WHAT ABOUT FOOTPRINTS? HOW CAN A HOLE BECOME A FOSSIL?

A footprint fossil begins with a perfectly ordinary step.

An animal walks across a surface soft enough to receive an impression but firm enough to retain its shape. Mud and damp sand are excellent candidates.

The track must then be buried before wind, waves, rain, other animals or enthusiastic members of the herd destroy it. A new layer of sediment settles over the surface, filling and protecting the impression.

With continued burial, both layers may harden into rock. Millions of years later, erosion separates them again. One surface may preserve the original footprint as a depression. The layer that filled the print may preserve a raised natural cast.

Tracks are not simply stamps of the foot. The animal’s weight can deform layers beneath the surface, producing structures known as undertracks. These may be less anatomically precise than the original print but can still record the passage of the animal.

Interpreting tracks requires caution. Wetness, sediment texture, erosion and the animal’s movement can all alter a footprint’s appearance. The same animal could leave surprisingly different tracks after walking only a short distance.

We must study the track, the sediment and the entire trackway—not merely find three vaguely pointed marks and immediately summon the media.

HOW OLD DOES SOMETHING HAVE TO BE BEFORE IT BECOMES A FOSSIL?

You may have heard that a fossil must be at least 10,000 years old.

That figure is commonly used as a practical dividing line in educational materials and some regulatory contexts, but nature has not installed an official fossil clock that rings at midnight on an organism’s ten-thousandth birthday.

We may use terms such as subfossil for relatively recent remains that are not fully fossilized or that retain considerable original material. The terminology can vary depending on the field, material and legal jurisdiction.

Age alone is not the only consideration. Geological context, preservation and scientific usage all matter.

An ammonite shell 100 million years old is unquestionably a fossil. A mammoth tusk 30,000 years old is also a fossil, even if some of its original material remains. Very recent bones from an archaeological site may be described as remains rather than fossils.

The boundary is useful, but it is not a magical transformation.

ARE ALL FOSSILS VISIBLE?

Not remotely. Some of the most important fossils on Earth are microscopic.

Microfossils include fossilized pollen, spores, algae, bacteria, protists and the tiny shells or skeletal elements of marine organisms.

They may be smaller than a grain of sand, yet they occur in enormous numbers and can be tremendously useful. Because some microscopic organisms evolved rapidly and lived across wide geographic areas, their fossils can help scientists date and correlate rock layers.

Microfossils also reveal ancient environments. Different species lived under different conditions, so their presence can provide clues about water depth, temperature, salinity, oxygen levels and climate.

Oil and gas exploration has long relied on micropalaeontology to interpret underground rock layers. A microscopic fossil no larger than a speck of dust may help identify the age and environment of rocks buried kilometres beneath the surface.

Dinosaurs receive the posters. Microfossils quietly organize geological time. Alas, always the bridesmaid, never the bride... Dinos get all the love.

CAN MOLECULES BE FOSSILS?

Ancient life can sometimes leave chemical evidence even when no recognizable body or trace remains.

These signals are often called chemical fossils or biomarkers.

Certain molecules are associated with particular groups of organisms or biological processes. Modified versions of those compounds may survive in ancient rocks, providing evidence that particular kinds of life were present.

Stable isotope patterns can also carry biological information. Living organisms use elements in ways that can leave characteristic chemical signatures in their tissues or surrounding sediments.

Chemical fossils require careful interpretation because geological heat, pressure and contamination can alter molecular evidence. But when combined with other data, they can help scientists investigate some of the earliest chapters in the history of life.

Sometimes life leaves a bone. Sometimes it leaves a footprint. Sometimes it leaves little more than chemistry.

IS A DINOSAUR SKELETON IN A MUSEUM MADE OF REAL FOSSILS?

Sometimes entirely. Sometimes partly. Sometimes hardly at all.

Complete dinosaur skeletons are rare. Museum mounts are often composites, combining fossil bones from more than one individual of the same species. Missing elements may be reconstructed as casts.

In some displays, the original fossils are too heavy, fragile or scientifically valuable to suspend in a dramatic pose. Museums may mount lightweight replicas while keeping the genuine fossils safely stored for research.

This does not make the display fake. A high-quality cast reproduces the shape and surface detail of the original fossil while protecting irreplaceable material. Casts can also be shared with museums, schools and researchers around the world.

Labels generally explain which elements are original fossils and which are reconstructed. It is always worth looking.

The glamorous skeleton towering over the gallery may be a carefully assembled ambassador for a far more fragmentary animal.

IS EVERY OLD BONE A FOSSIL?

No. Sometimes an old bone is just that, an old bone. Not a fossil. Age and appearance alone do not prove that something is fossilized. Modern bones can become stained by soil and minerals, making them look ancient. Conversely, genuine fossils do not always appear dramatically different from ordinary bone.

Identification may involve examining:

• Geological context
• Colour and density
• Surface texture
• Internal structure
• Mineral composition
• Associated fossils
• Degree of mineralization
• Evidence of recent organic material

And no, licking it is not the preferred scientific method but, I confess, it is helpful in the field. Not fully diagnostic, but helpful. I have a good friend Skippy who swears by it.

There is an old field trick based on the idea that porous fossil bone may stick slightly to the tongue, but modern bone can do the same, as can many ordinary rocks. The technique is unhygienic, unreliable and particularly regrettable when the mystery specimen is not bone at all.

Use a hand lens. Use comparative anatomy. Use laboratory analysis. Leave your tongue out of the peer-reviewed methodology.

WHY ARE FOSSILS SO RARE?

To become a fossil, an organism must pass through a series of improbable filters. Fossils are not rare per se, as I can think of localities with hundreds spread across the surface and more beneath, but they are rare in the sense that only a small percentage of the organisms that have lived have been preserved this way. To become a fossil is a bit of a process, as you might expect. 

First, the organism, dino, plant, or what have you, must die in a place where preservation is possible.

Then its remains must escape scavengers, decay, trampling, weather and destruction. They must be buried. The sediment must remain intact as it becomes rock. The fossil must survive heat, pressure, chemical alteration, faulting, erosion and the slow recycling of Earth’s crust.

Finally, it must become exposed—or be reached by excavation—at precisely the right time for someone to recognize it. Too early, and it remains buried. Too late, and erosion destroys it.

The fossil record is therefore both magnificent and profoundly incomplete.

Most organisms that ever lived left no known fossil. Entire species may have appeared, flourished and vanished without preserving a trace that we have yet discovered.

Soft-bodied organisms are especially underrepresented. Environments such as mountains, forests and tropical soils generally offer fewer opportunities for long-term preservation than lakes, river floodplains and marine sediments.

When we reconstruct ancient ecosystems, we are working with survivors of a second kind—not organisms that survived extinction, but evidence that survived geology.

IS A FOSSIL THE SAME THING AS A ROCK?

A fossil is preserved within a geological material, and many fossils have been heavily mineralized, but “fossil” and “rock” are not interchangeable terms.

A rock forms through geological processes and may contain fossils. A fossil is evidence of past life preserved within rock, sediment, amber, ice or another natural context.

The distinction can become wonderfully complicated.

A fossil shell may retain original shell material. A petrified log may be almost entirely mineral. A mould contains none of the organism but preserves its shape. A trace fossil may consist entirely of disturbed sediment.

So, is a fossil a rock? Sometimes it has effectively become one. But what makes it a fossil is not simply its material. It is the biological information it carries.

WHAT CAN ONE FOSSIL TELL US?

Far more than its name. A fossil’s anatomy may reveal how an organism moved, fed or defended itself. Growth rings can record seasons or age. Microscopic wear on teeth may reveal diet. Bone injuries can preserve evidence of accidents, disease, combat and healing.

The surrounding sediment can tell us whether the organism lived in a river, desert, forest, lake or sea. Associated fossils help reconstruct the plants, animals and microorganisms sharing that environment.

Chemical analysis may reveal temperature, water conditions, migration or food-web relationships. Footprints may preserve speed and direction. Burrows can reveal oxygen levels in ancient sediments. Coprolites can contain the remains of a final meal.

Even the way a body was buried matters. Were the bones scattered by a river? Gnawed by scavengers? Transported by waves? Buried in a sudden flood?

The study of what happens to an organism between death, burial and discovery is called taphonomy. It helps palaeontologists separate evidence of how an animal lived from evidence of what happened after it died. A fossil is not simply an object. It is a scene containing clues.

WHAT IS NOT A FOSSIL?

Not every interesting pattern in rock was created by life.

Mineral crystals, concretions, sedimentary structures and weathered rocks can resemble eggs, shells, bones, skin, feathers or entire mysterious creatures. These geological look-alikes are sometimes called pseudofossils. Or, leaverits, as in leave it right there. 

Manganese minerals can grow in branching patterns resembling ferns. Concretions can look remarkably like eggs. Layered rocks may split into shapes suggesting shells or leaves. Some rocks possess suspiciously skull-like features and an unreasonable amount of charisma.

The human brain excels at recognizing familiar forms. This tendency, called pareidolia, helps us see faces in clouds, animals in tree bark and dinosaurs in the landscaping gravel.

None of this makes an unusual rock uninteresting. A pseudofossil can still be geologically beautiful.

It simply tells a different story.

THE FOSSIL RECORD IS BIASED

The fossil record is sometimes imagined as a great stone library containing the complete history of life.

It is more like a library after fire, flood, renovation, several lost catalogues and four billion years of questionable management.

Some chapters are richly detailed. Others contain a few scattered sentences. Entire volumes are missing.

Organisms with shells, bones or teeth are more likely to be preserved than soft-bodied organisms. Aquatic environments are generally better represented than upland habitats. Abundant and widespread species have a greater chance of discovery than rare, geographically restricted ones.

Even human activity introduces bias. Fossils are more likely to be discovered where rocks are exposed, where researchers can travel and where scientific work has been funded.

Palaeontologists must account for these biases when interpreting patterns of diversity, evolution and extinction. An absence of fossils does not necessarily prove that an organism was absent. It may mean that the right rocks were not deposited, did not survive or have not yet been explored.

The fossil record is incomplete. But incomplete does not mean useless. It means we must read it carefully.

A FOSSIL IS A RELATIONSHIP

There is another way to think about fossils. A fossil is not merely a thing that was once alive. It is the relationship between life and the Earth that preserved it. The organism contributed its body or behaviour. The environment supplied mud, sand, ash, resin, ice or minerals. Time transformed the evidence. Erosion returned it to the light. Then someone noticed.

That final part matters. A fossil can lie exposed among a thousand ordinary stones and remain silent until a curious person stops, looks closely and asks a question.

What made this shape? Why is this shell inside a mountain? Who walked here? What kind of world once existed beneath my feet? Every fossil discovery begins with attention. And many great specimens have been found by folk of all ages (many of them too young to vote) who take notice of the world around them.

A MESSAGE THAT SURVIVED

To hold a fossil is to hold a contradiction. It is evidence of death that teaches us about life. It is a motionless object that may record movement. It is a fragment capable of revealing an ecosystem.

It is ancient, yet newly discovered.

The animal, plant or microorganism did not set out to leave us a message. The footprint was not made for our benefit. The shell did not settle onto the seafloor hoping to appear one day in a museum drawer.

And yet the evidence survived.

Across burial, mineralization, shifting continents, rising mountains and relentless erosion, something remained.

A tooth.

A leaf.

A burrow.

A trail across the mud.

A tiny, stubborn piece of deep time waiting for someone to recognize it.

That is a fossil.

CHARLES DARWIN: A TASTE FOR STUDIES

Chelonia. Schildkröten by Ernst Haeckel, 1904

Care for some tarantula with that walrus? No? how about some Woolly mammoth?

While eating study specimens is not de rigueur today, it was once common practice for researchers in the 1700-1880s. 

The English naturalist, Charles Darwin belonged to an elite men's club dedicated to tasting exotic meats. In his first book, Darwin wrote almost three times as much about dishes like armadillo and tortoise urine as he did on the biogeography of his Galapagos finches. 

From his great love of gastronomy, I am surprised any of his tasty specimens made it back from his historic voyage on the HMS Beagle — particularly the turtles.

One of the most famous scientific meals occurred one Saturday evening on the 13th of January, 1951. This was at the 47th Explorers Club Annual Dinner (ECAD) when members purportedly dined on a frozen woolly mammoth. 

Commander Wendell Phillips Dodge was the promotor of the banquet. He sent out press notices proclaiming the event's signature dish would be a selection of prehistoric meat. Whether Dodge did this simply to gain attendees or play a joke remains a mystery. 

The prehistoric meat was supposedly found at Woolly Cove on Akutan in the Aleutians Islands of Alaska, USA, by the eminent polar explorers' Father Bernard Rosecrans Hubbard, American geologist, explorer sometimes called the Glacier Priest, and polar explorer Captain George Francis Kosco of the United States Navy.

Fried Tarantula & Goat Eyeballs

This much-publicized meal captured the public’s imagination and became an enduring legend and source of pride for the Club, popularizing an annual menu of exotics that continues today. The Club is well-known for its notorious hors d’oeuvres like fried tarantulas and goat eyeballs as it is for its veritable whose who of notable members — Teddy Roosevelt, Neil Armstrong, Buzz Aldrin, Roy Chapman Andrews, Thor Heyerdahl, James Cameron.

The Yale Peabody Museum holds a sample of meat preserved from the 1951 meal, interestingly labelled as a South American Giant Ground Sloth, Megatherium, not Mammoth. The specimen of meat from that famous meal was originally designated BRCM 16925 before a transfer in 2001 from the Bruce Museum to the Yale Peabody Museum of Natural History (New Haven, CT, USA) where it gained the number YPM MAM 14399.

The specimen is now permanently deposited in the Yale Peabody Museum with the designation YPM HERR 19475 and is accessible to outside researchers. The meat was never fixed in formalin and was initially stored in isopropyl alcohol before being transferred to ethanol when it arrived at the Peabody Museum. DNA extraction occurred at Yale University in a clean room with equipment reserved exclusively for aDNA analyses.

In 2016, Jessica Glass and her colleagues sequenced a fragment of the mitochondrial cytochrome-b gene and studied archival material to verify its identity, which if genuine, would extend the range of Megatherium over 600% and alter views on ground sloth evolution. 

Mammoth, Megatherium — Green Sea Turtle

Their results showed that the meat was not Mammoth or Megatherium, but a bit of Green Sea Turtle, Chelonia mydas. So much for elaborate legends. The prehistoric dinner was likely meant as a publicity stunt. 

Glass's study emphasizes the value of museums collecting and curating voucher specimens, particularly those used for evidence of extraordinary claims. Not so long before Glass et al. did their experiment, a friend's mother (and my kayaking partners) served up a venison steak from her freezer to dinner guests in Castlegar that hailed from 1978. Tough? Inedible? I have it on good report that the meat was surprisingly divine.

Reference: Glass, J. R., Davis, M., Walsh, T. J., Sargis, E. J., & Caccone, A. (2016). Was Frozen Mammoth or Giant Ground Sloth Served for Dinner at The Explorers Club?. PloS one, 11(2), e0146825. https://doi.org/10.1371/journal.pone.0146825

Image: Chelonia. Schildkröten by Ernst Haeckel, 1904, Prints & Photographs Division, Library of Congress, LC-DIG-ds-07619.

Join the Explorer's Club

Fancy yourself an explorer who should join the club? Here is a link to their membership application. The monied days of old are still inherent, but you will be well pleased to learn you can now join for as little as $50 US.

Link: https://www.explorers.org/wp-content/uploads/Membership-Application_2021-11-19.pdf

TUSKED TITANS OF THE ARCTIC: WALRUS ᐊᐃᕕᖅ

A lazy walrus lounges on an ice floe, its massive, blubbery body shimmering under the low Arctic sun. 

With a deep, rumbling sigh, it shifts its weight and scratches an itch on its side—more out of habit than necessity. Life, for this marine titan, moves at the pace of the tides.

Odobenus rosmarus, the walrus is the only surviving member of the family Odobenidae, a once-diverse group of pinnipeds that includes extinct relatives such as Dusignathus and Pontolis. 

Fossil remains place their lineage back to the late Miocene, around 10–11 million years ago. Early odobenids first appeared in the North Pacific and were more varied than the tusked, bottom-feeding walrus we know today—some had shorter tusks or none at all, and many hunted fish rather than clams.

These ancient walruses belonged to a broader superfamily, the Pinnipedia, which also includes seals and sea lions. Genetic and fossil evidence suggests pinnipeds split from terrestrial carnivores roughly 25–30 million years ago, likely from bear-like ancestors that took to the water during the Oligocene. Odobenids evolved later, perfecting their specialization as suction feeders. 

Their powerful tongues can vacuum soft-bodied mollusks straight from their shells—a skill that defines modern walrus diets.

Today, walruses inhabit the icy Arctic and subarctic waters of the Northern Hemisphere, with two recognized subspecies: the Atlantic walrus, O. r. rosmarus, found in the Canadian Arctic and Greenland, and the Pacific walrus, O. r. divergens, ranging from the Bering Sea to the Chukchi Sea. They prefer shallow continental shelf regions where bivalves abound and haul out on sea ice or rocky shores in vast, noisy colonies.

Despite their ponderous appearance, walruses are powerful swimmers and social creatures with intricate communication and hierarchy systems. Their tusks—elongated canines present in both males and females—serve for dominance displays, hauling out, and defense. 

To Arctic peoples, walruses have long been vital for food, hides, and ivory, woven into traditional lifeways and mythology.

In Inuktitut, the word for walrus is “aiviq” (ᐊᐃᕕᖅ). It’s pronounced roughly eye-vik or ay-vik, depending on the dialect. The plural form is “aiviat” (ᐊᐃᕕᐊᑦ). The walrus, aiviq, holds deep cultural and spiritual importance in Inuit communities, long valued for its meat, ivory, and hide—vital resources for survival in the Arctic.

From Miocene shores to the modern polar ice, the walrus story is one of adaptation and endurance—a lineage that has survived shifting seas and ice ages, still scratching its ancient itch beneath the northern sun.

BARNACLES: K'WITA'A

One of the most interesting and enigmatic little critters we find at the seashore are barnacles. They cling to rocks deep in the sea and at the waters' edge, closed to our curiosity, their domed mounds like little closed beaks shut to the water and the world.

They choose their permanent homes as larvae, sticking to hard substrates that will become their permanent homes for the rest of their lives. It has taken us a long time to find how they actually stick or what kind of "glue" they were using.

Remarkably, the barnacle glue sticks to rocks in a similar way to how red cells bind together. Red blood cells bind and clot with a little help from some enzymes. 

These work to create long protein fibres that first blind, clot then form a scab. The mechanism barnacles use, right down to the enzyme, is very similar. That's especially interesting as about a billion years separate our evolutionary path from theirs.

So, with the help of their clever enzymes, they can affix to most anything – ship hulls, rocks, and even the skin of whales. If you find them in tidepools, you begin to see their true nature as they open up, their delicate feathery finger-like projections flowing back and forth in the surf.

One of my earliest memories is of playing with them in the tidepools on the north end of Vancouver Island. It was here that I learned their many names. In the Kwak'wala language of the Pacific Northwest, the word for barnacles is k̕wit̕a̱'a — and if it is a very small barnacle it is called t̕sot̕soma — and the Kwak'wala word for glue is ḵ̕wa̱dayu.

HOW DO FOSSILS FORM? CAN I BECOME A FOSSIL?

Let us begin with a rather brutal truth. You are probably not going to become a fossil.

Neither am I.

Neither is the salmon that washed onto the riverbank, the beetle beneath the cedar tree nor the unfortunate vole currently being carried away by an owl.

Most living things disappear completely after death. 

They are eaten, scavenged, scattered, dissolved, trampled, weathered or dismantled by bacteria and fungi. Their nutrients return to the ecosystem, but their physical remains leave no lasting geological record.

Fossilization is the exception. Yet, it is still a conversation I have with my fossil friends more times than I can count. We would all love to become fossils ourselves. Geeky? Yes, but one can dream!

To become a fossil requires the right organism to die in the right place, at the right time, under the right conditions—and then remain protected through thousands, millions or even billions of years of geological upheaval.

To become a fossil is to win one of the most improbable lotteries on Earth.

Even then, success is not guaranteed. A fossil must survive burial, pressure, mineral-rich water, chemical change, shifting continents, rising mountains and erosion. Finally, it must reach the surface at precisely the moment when someone is there to recognize it.

Too early, and it remains hidden. Too late, and it erodes into dust.

Fossilization is therefore not a single event. It is a journey—a long and perilous passage from life to stone and, with extraordinary luck, back into the light.

STEP ONE: SOMETHING DIES

Upper Cambrian Trilobite

Every body fossil begins with death. This may happen quietly. A leaf drops into a lake. A clam dies on the seafloor. A fish sinks into deep water.

Or it may happen with considerably more geological enthusiasm.

A volcanic eruption blankets an ecosystem in ash. A flood sweeps animals into a river channel. A mudslide buries an entire community. A tree releases sticky resin around a struggling insect. A creature wanders into natural tar and discovers, much too late, that the surface is not as solid as advertised.

The cause of death can influence what happens next, but death alone does not begin fossilization.

The critical issue is what happens to the remains immediately afterward.

A dead organism is suddenly of great interest to nearly everything around it. Scavengers arrive. Insects feed and lay eggs. Microorganisms begin breaking down tissues. Sunlight, oxygen, water and temperature all accelerate physical and chemical change.

Fossilization begins as a race between destruction and preservation. Destruction usually wins.

STEP TWO: THE BODY BEGINS TO DECAY

Soft tissues generally disappear first.

Eyes, skin, internal organs, muscles and other delicate tissues are quickly attacked by bacteria, fungi, insects and scavengers. Under ordinary conditions, little may remain after days, weeks or months.

Hard parts last longer. Bones, teeth, shells, exoskeletons and wood resist decay, giving them a greater opportunity to be buried. This is why the fossil record contains far more shells and teeth than jellyfish and worms.

It is also why our picture of ancient life is biased.

An ecosystem may have been filled with soft-bodied creatures, but unless unusually favourable conditions preserved them, their absence from the fossil record can make them nearly invisible to us.

Imagine trying to reconstruct the modern ocean using only shark teeth, clam shells and the occasional whale bone. You would learn a great deal, but you would miss most of the story.

Hard body parts and rapid burial are two of the most important factors increasing an organism’s chance of fossilization. Without them, the journey often ends before it begins.

STEP THREE: RAPID BURIAL CHANGES EVERYTHING

Burial is the great opportunity.

When remains are quickly covered by mud, sand, silt, volcanic ash or another material, they become less accessible to scavengers and less exposed to weather.

Burial can also reduce the amount of oxygen reaching the remains. Many bacteria and scavenging organisms require oxygen, so low-oxygen conditions can slow decomposition.

This does not mean all buried organisms become fossils. Most do not. But rapid burial buys time.

The best locations for fossilization are therefore usually places where sediment accumulates:

• River channels and floodplains
• Lakes
• Deltas
• Beaches
• Shallow seas
• Deep ocean basins
• Sand dunes
• Caves
• Volcanic ash deposits
• Tar seeps
• Peat bogs

An animal dying on a rocky mountaintop has poor prospects. Its remains may be scattered by wind, water and scavengers without ever being buried.

A clam dying on a muddy seafloor has much better odds. Sediment is already accumulating around it, and its shell is resistant to decay.

This is one reason marine organisms are so well represented in the fossil record. Oceans have covered enormous portions of the planet, and their floors provide vast areas where sediment can accumulate.

Many rocks now exposed high in mountains began as sediment beneath ancient seas.

Finding seashells on a mountain does not mean clams were once exceptionally skilled climbers. It means the seafloor was lifted. We can look to the Burgess Shale Biota as a wonderful example of this.

HOW MUCH BURIAL IS ENOUGH?

The first thin layer may protect remains temporarily, but continued burial is usually necessary for long-term preservation.

New sediment settles on top of older sediment. Layer after layer accumulates, gradually increasing the pressure on the material below.

The sediment becomes compacted. Water is squeezed from the spaces between grains. Dissolved minerals precipitate and act like cement, binding those grains together.

Loose mud may become shale. Sand may become sandstone. Accumulations of shells and carbonate mud may become limestone.

Sedimentary rocks form when deposited material is buried, compacted and cemented. These rocks are particularly important to palaeontology because they form at Earth’s surface under conditions capable of preserving evidence of life.

Fossils are rarely found in rocks that once existed as molten magma. Lava is not known for its gentle handling of organic remains.

Metamorphism can also destroy fossils. When sedimentary rocks are subjected to intense heat and pressure, their minerals recrystallize. Delicate structures may be distorted or erased entirely.

Fossils therefore survive best when their rocks experience enough burial to become solid, but not so much heat and pressure that their history is cooked beyond recognition.

It is a narrow path. Sinking to the bottom of a body of water with little to no oxygen will also do the trick in many cases. 

THE ODDS ARE NOT IN YOUR FAVOUR

Even rapid burial does not guarantee fossilization. The remains may later dissolve. Groundwater may carry them away. Geological pressure may crush them. The surrounding rock may be heated, folded, faulted or dragged deep into Earth’s crust.

Entire fossil-bearing formations can disappear through erosion or be transformed so completely that no recognizable trace of life remains.

Then there is the final difficulty: discovery.

A fossil may remain safely hidden underground for millions of years. Tectonic movement must lift the fossil-bearing rocks, and erosion must remove enough material to expose them at the surface.

Exposure creates another race against time.

Wind, rain, waves, frost and flowing water reveal fossils—but they also destroy them. A bone that survived 100 million years underground may begin crumbling within a few seasons of reaching the surface.

Someone must pass by during that brief window, notice an unusual shape and understand that it matters.

A line of vertebrae. The curve of a shell. A tooth emerging from sandstone. A delicate leaf pressed into shale.

The moment of discovery may feel sudden, but it is the final stage of a journey that began with death and continued through deep time.

AN IMPROBABLE MESSAGE FROM THE PAST

Fossils are often described as the remains of dead organisms. I prefer to think of them as survivors.

They survived decay, scavengers and weather. They survived burial, pressure and chemical change. They survived the shifting, folding and fracturing of Earth’s crust. Finally, they survived erosion long enough for someone to find them.

OF LAND AND SEA

Our dear penguins, seals, sea lions, walruses, whales, crocodiles and sea turtles were once entirely terrestrial. Yes, they lived mostly or entirely on land. 

Many of these once land-dwelling animals returned to the sea throughout evolutionary history. We have beautifully documented cases from amphibians, reptiles, birds and mammals from over 30 different lineages over the past 250 million years.

Some dipped a toe or two into freshwater ponds, but make no mistake, they were terrestrial. Each of these animals had ancestors that tried out the sea and decided to stay. They evolved and employed a variety of adaptations to meet their new saltwater challenges. Some adapted legs as fins, others became more streamlined, and still, others developed specialized organs to extract dissolved oxygen from the water through their skin or gills. The permutations are endless.

Returning to the sea comes with a whole host of benefits but some serious challenges as well. Life at sea is very different from life on land. Water is denser than air, impacting how an animal moves, sees and hears. More importantly, it impacts an air-breathing animal's movement on a pretty frequent basis. If you need air and haven't evolved gills, you need to surface frequently. Keeping your body temperature at a homeostatic level is also a challenge as water conducts heat much better than air. Even with all of these challenges, the lure of additional food sources and freedom of movement kept those who tried the sea in the sea and they evolved accordingly.

Most major animal groups appear for the first time in the fossil record half a billion years ago. We call this flourishing of species the Cambrian Explosion. While this was a hugely intense period of species radiation, the evolutionary origins of animals are likely to be significantly older. About 700 million years ago the Earth was covered in ice and snow. This was an ice age so intense we refer to this time in our ancient history as Snowball Earth. Once that ice receded, it exposed rocks that contained a variety of weird and wonderful fossils that speak to ancient animals that are only now being studied.

Dr Frankie Dunn, a palaeontologist and an Early Career Research Fellow at the Oxford University Museum of Natural History and Merton College is one of the folks who are examining this early history of some of our first animals. Her research focuses on the origin and early evolution of animals and particularly on the fossil record of the late Ediacaran Period (570 – 540 million years ago).  Dr Dunn's research is exploring ancient species like the long-extinct Rangeomorpha to help understand how animal body plans evolved in deep time well before the divergence of the extant (living) animal lineages.

Andy Temple (bless him) sent me a link for an online talk Dr Dunn is giving, The Chronicles of Charnia, Wed, June 17th at 7PM. She's based in Oxford so adjust your timezone accordingly. The talk is free but booking is required. Here's the link: https://event.webinarjam.com/register/59/xyy07flg 

This is an interesting article from Alicia Ault writing for the Smithsonian who interviewed Nick Pysenson and Neil Kelley about some of their research that touches on this area. They published a paper on it in the journal Science. Here's the link: https://science.sciencemag.org/content/348/6232/aaa3716

And Ault's work is definitely worth a read: https://www.smithsonianmag.com/smithsonian-institution/take-deep-dive-reasons-land-animals-moved-seas-180955007/