PTEROCEPHALIA FROM THE MCKAY GROUP

A lovely Pterocephalia trilobite from Upper Cambrian, Furongian strata of the McKay Group, Kootenay Rockies. 

The McKay Group has been explored extensively these past few years by Chris New and Chris Jenkins of Cranbrook, British Columbia. 

Together, these two avid trilobite enthusiasts have opened up considerable knowledge on the exposures, collaborating with researchers such as Brian Chatterton and Rudy Lerosey-Aubril. They have unearthed many new specimens and several new species. 

Pterocephalia from this region are relatively common. It was the keen eyes of Chris Jenkins that spotted the unusual preservation of the gut tract that led to the publication by Chatterton et al. in 1994. 

Rudy Lerosey-Aubril published a paper in 2017 on phosphatized gut remains — relatively common in this taxon at this site. Lerosey-Aubril’s paper was on an aglaspidid, a combjelly, and the gut of another trilobite. 

Skeletal remains of trilobites are abundant in Palaeozoic rock but soft parts are rarely preserved. There have been a few papers on trilobite gut remains from Canada and on abundant trilobite faunas of the Kaili Formation of Guizhou, China. The Kaili contains one of the earliest middle Cambrian Burgess Shale-type deposits, sharing many faunal elements (see http://hdl.handle.net/1811/24227) with the older Chengjiang Biota (Chen 2004; Hou et al. 2004) and the younger Burgess Shale Biota (Briggs et al. 1994). 

The biota, facies description, and regional stratigraphy of the Kaili Biota were discussed and reviewed in Zhao et al. (2002, 2005) and Lin et al. (2005). Chinese colleagues (Zhao et al. 1994b, 1996, 1999, 2001, 2002) have illustrated many Kaili arthropods with soft-part preservation, but most of their systematic descriptions are yet to be completed.

References: Chatterton BD, Johanson Z, Sutherland G. 1994. Journal of Paleontology 68:294-305. 

Lin, Jih-Pai. (2007). Preservation of the gastrointestinal system in Olenoides (Trilobita) from the Kaili Biota (Cambrian) of Guizhou, China. Memoirs of the Association of Australasian Palaeontologists. 33. 179-189. 

Photo: This specimen was collected by Dan Bowden and photographed by the Huntress. It has been checked for the dark telltale signs of phosphatized gut remains, but sadly no luck!

WEE BABY EURYPTERID

This adorable wee baby with his teeny aquatic mittens on is a eurypterid from exposures in New York, USA. 

This cutie is one of my favourites. I imagine him wearing mittens but that, of course, is not the case at all.  

This fellow is just under a centimetre in length but his cousins grew larger than a human. Eurypterids were the largest known arthropods to ever live. 

The largest, Jaekelopterus, reached 2.5 meters (8.2 ft) in length — significantly larger than some of his very tiny cousins — most growing to less than 20 centimetres (8 inches) in length. 

More commonly known as sea scorpions, the now-extinct eurypterids were arthropods that lived during the Paleozoic Era. We saw the first of their brethren during the Ordovician and the last of them during the End-Permian Mass Extinction Event. In between, they thrived and irradiated out to every niche within our ancient seas and many later forms survived and thrived in brackish and freshwater. 

The group Arthropoda includes invertebrate animals with exoskeletons, segmented bodies, and paired joint appendages. Eurypterids had six sets of appendages. You can clearly see the segmented body on this cutie, which is one of the defining characteristics of arthropods. The first set was modified into pinchers which are used for feeding. The largest appendage visible in this fossil is a broad paddle that E. tetragonophthalmus used to swim.

This first eurypterid, Eurypterus remipes, was discovered in New York in 1818. It is an iconic fossil for this region and was chosen as the state's official fossil in 1984. An excellent choice as most of the productive eurypterid-bearing outcrops are within the state's boundaries. Most of the fossils we find from them, whether body fossils or trace fossils are from fossil sites in North America and Europe This is because the group lived primarily in the waters around and within the ancient supercontinent of Euramerica. 

Only a handful of eurypterid groups spread beyond the confines of Euramerica and a few genera, such as Adelophthalmus — the longest lived of all known eurypterid genera — and the giant predatory Pterygotus, achieved a cosmopolitan distribution so we find their fossil remains worldwide today. 

Interestingly, the type species, Pterygotus anglicus, was first through to be the remains of a massive fish by Swiss naturalist Louis Agassiz who described it in 1839 — hence the poorly chosen name Pterygotus, which translates to "winged fish. He did catch that embarrassing error five years later, but the name remains and will for all time.

SEA SCORPIONS: PREDATORS OF ANCIENT SEAS

About two dozen families of eurypterids “sea scorpions” are known from the fossil record.

Although these ancient predators have a superficial similarity, including a defensive needle-like spike or telson at their tail end, they are not true scorpions. They are an extinct group of arthropods related to spiders, ticks, mites and other extant creepy crawlies.

Eurypterids hunted fish in the muddy bottoms of warm shallow seas some 460 to 248 million years ago before moving on to hunting grounds in fresh and brackish water during the latter part of their reign. Their numbers diminished greatly during the Permian-Triassic extinction, becoming extinct by 248 million years ago.

Eurypterids are found in Canada, most notably at the Ridgemount Quarry near Niagara Falls. This near-perfect specimen of Eurypterus remipes — held by my cousin Sivert, hand-model extraordinaire — was named the official state fossil of New York in 1984.

EURYPTERUS SEA SCORPIONS

The impressive homeotype specimen of Eurypterus lacustris from Late Silurian deposits in New York. UCMP Berkeley's palaeontological collections.

Eurypterus is by far the most well-studied and well-known eurypterid and its fossil specimens probably represent more than 90% of all known eurypterid specimens.

About two dozen families of eurypterids “sea scorpions” are known from the fossil record. Although these ancient predators have a superficial similarity, including a defensive needle-like spike or telson at their tail end, they are not true scorpions. They are an extinct group of arthropods related to spiders, ticks, mites and other extant creepy crawlies.

The first fossil of Eurypterus was found in 1818 by S. L. Mitchill, a fossil collector. It was recovered from the Bertie Formation of New York, near Westmoreland, Oneida County. Mitchill interpreted the appendages on the carapace as barbels arising from the mouth. He consequently identified the fossil as a catfish of the genus Silurus. In 1825, American zoologist James Ellsworth De Kay identified the fossil correctly as an arthropod. He named it Eurypterus remipes and established the genus Eurypterus in the process. The name means "wide wing" or "broad paddle", referring to the swimming legs, from Greek εὐρύς (eurús, wide) and πτερόν (pteron, wing).

However, De Kay thought Eurypterus belonged to branchiopods, a group of crustaceans that includes water fleas. Soon after, Eurypterus lacustris was also discovered in New York in 1835 by the palaeontologist Richard Harlan. Another species was discovered in Estonia in 1858 by Jan Nieszkowski. He considered it to be of the same species as the first discovery (E. remipes); though it has since been renamed Eurypterus tetragonophthalmus.

Jan Nieszkowski's 1858 dissertation

These specimens from Estonia are often of extraordinary quality, retaining the actual cuticle of their exoskeletons. In 1898, the Swedish palaeontologist Gerhard Holm separated these fossils from the bedrock with acids. Holm was then able to examine the almost perfectly preserved fragments under a microscope. His remarkable study led to the modern breakthrough in eurypterid morphology.

More fossils were recovered in great abundance in New York in the 19th century, and elsewhere in eastern Eurasia and North America. Today, Eurypterus remains one of the most commonly found and best-known eurypterid genera, comprising more than 95% of all known eurypterid fossils.

Eurypterids hunted fish in the muddy bottoms of warm shallow seas some 460 to 248 million years ago before moving on to hunting grounds in fresh and brackish water during the latter part of their reign. Their numbers diminished greatly during the Permian-Triassic extinction, becoming extinct by 248 million years ago.

Image: Dorsal and ventral aspects of Eurypterus tetragonophthalmus, from Jan Nieszkowski's 1858 dissertation; By Jan Nieszkowski (1833-1866) - Nieszkowski J. De euryptero remipede: dissertatio inauguralis. Dorpat: H. Laakmann, 1858, Public Domain, https://commons.wikimedia.org/w/index.php?curid=11225856

HADROSAUR TOOTH FROM ALBERTA

A rare and very beautifully preserved Cretaceous Hadrosaur Tooth. This lovely specimen is from one of our beloved herbivorous "Duck-Billed" dinosaurs from 68 million-year-old outcrops near Drumheller, Alberta, Canada, and is likely from an Edmontosaurus.

When you scour the badlands of southern Alberta, most of the dinosaur material you'll find are from hadrosaurs. These lovely tree-less valleys make for excellent-searching grounds and have led us to know more about hadrosaur anatomy, evolution, and paleobiology than for most other dinosaurs.

We have oodles of very tasty specimens and data to work with. We've got great skin impressions and scale patterns from at least ten species and interesting pathological specimens that provide valuable insights into hadrosaur behaviour. Locally, we have an excellent specimen you can visit in the Courtenay and District Museum on Vancouver Island, Canada. The first hadrosaur bones were found on Vancouver Island a few years back by Mike Trask, VIPS, on the Trent River near Courtenay.

The Courtenay hadrosaur is a first in British Columbia, but our sister province of Alberta has them en masse. Given the ideal collecting grounds, many of the papers on hadrosaurs focus on our Canadian finds. These herbivorous beauties are also found in Europe, South America, Mexico, Mongolia, China, and Russia. Hadrosaurs had teeth arranged in stacks designed for grinding and crushing, similar to how you might picture a cow munching away on the grass in a field. These complex rows of "dental batteries" contained up to 300 individual teeth in each jaw ramus. But even with this great number, we rarely see them as individual specimens.

They didn't appear to shed them all that often. Older teeth that are normally shed in our general understanding of vertebrate dentition, were resorped, meaning that their wee osteoclasts broke down the tooth tissue and reabsorbed the yummy minerals and calcium.

As the deeply awesome Mike Boyd notes, "this is an especially lucky find as hadrosaurs did not normally shed so much as a tooth, except as the result of an accident when feeding or after death. Typically, these fascinating dinosaurs ground away their teeth... almost to nothing."

In hadrosaurs, the root of the tooth formed part of the grinding surface as opposed to a crown covering over the core of the tooth. And curiously, they developed this dental arrangement from their embryonic state, through to hatchling then full adult.

There's some great research being done by Aaron LeBlanc, Robert R. Reisz, David C. Evans and Alida M. Bailleul. They published in BMC Evolutionary Biology on work that looks at the histology of hadrosaurid teeth analyzing them through cross-sections. Jon Tennant did a nice summary of their research. I've included both a link to the original journal article and Jon Tennant's blog below.

LeBlanc et al. are one of the first teams to look at the development of the tissues making up hadrosaur teeth, analyzing the tissue and growth series (like rings of a tree) to see just how these complex tooth batteries formed.

They undertook the first comprehensive, tissue-level study of dental ontogeny in hadrosaurids using several intact maxillary and dentary batteries and compared them to sections of other archosaurs and mammals. They used these comparisons to pinpoint shifts in the ancestral reptilian pattern of tooth ontogeny that allowed hadrosaurids to form complex dental batteries.

References:

LeBlanc et al. (2016) Ontogeny reveals function and evolution of the hadrosaurid dinosaur dental battery, BMC Evolutionary Biology. 16:152, DOI 10.1186/s12862-016-0721-1 (OA link)

To read more from Jon Tennant, visit: https://blogs.plos.org/paleocomm/2016/09/14/all-the-better-to-chew-you-with-my-dear/

Photo credit: Derrick Kersey. For more awesome fossil photos like this from Derrick, visit his page: https://www.facebook.com/prehistoricexpedition/

CASTLE PEAK: JET RANGER

If you look closely, you can see a wee jet ranger helicopter hovering over a very chilly Castle Peak in the southern Chilcotin Range, British Columbia, Canada. 

Castle Peak was our glorious landmark and loadstone of basalt that marked the spot on our Jurassic/Triassic palaeo adventures collecting about 7000 ft. The peak itself reaches higher still to around 8,176 ft.

The late Hettangian ammonite fauna from Taseko Lakes is diverse and relatively well‐preserved. Over three field seasons from 2001-2003, thirty-five taxa from the Mineralense and Rursicostatum zones were studied and three new species discovered and named: Fergusonites hendersonae, Eolytoceras constrictum and Pseudaetomoceras victoriense. This material is very important as it greatly expands our understanding of the fauna and ranges of ammonites currently included in the North American regional ammonite zonation. 

I had the very great honour of having the newly named, Fergusonites hendersonae, a new species of nektonic carnivorous ammonite, named after me by palaeontologist Louse Longridge from the University of British Columbia. 

I had met Louise as an undergrad and was pleased as punch to hear that she would be continuing the research by Dr. Howard Tipper, the authority on this area of the Chilcotins and Haida Gwaii — which he dearly loved. 

"Tip" was a renowned Jurassic ammonite palaeontologist and an excellent regional mapper who mapped large areas of the Cordillera. He made significant contributions to Jurassic paleobiogeography and taxonomy in collaboration with Dr. Paul Smith, Head of Earth and Ocean Science at the University of British Columbia. 

Tip’s regional mapping within BC has withstood the test of time and for many areas became the regions' base maps for future studies. The scope of Tip’s understanding of Cordilleran geology and Jurassic palaeontology will likely never be matched. He passed away on April 21, 2005. His humour, knowledge and leadership will be sorely missed. 

Before he left us, he shared that knowledge with many of whom would help to secure his legacy for future generations. We did several trips over the years up to the Taseko Lake area of the Rockies joined by many wonderful researchers from Vancouver Island Palaeontological Society and Vancouver Paleontological Society, as well as the University of British Columbia. Both Dan Bowen and John Fam were instrumental in planning those expeditions and each of them benefited greatly from the knowledge of Dr. Howard Tipper. 

If not for Tipper's early work in the region, our shared understanding and much of what was accomplished in his last years and after his passing would not have been possible. 

Over the course of three field seasons, we endured elevation sickness, rain, snow, grizzly bears and very chilly nights  — we were sleeping right next to a glacier at one point — but were rewarded by the enthusiastic crew, helicopter rides — which really cut down the hiking time — excellent specimens including three new species of ammonites, along with a high-spired gastropod and lobster claw that have yet to be written up. This area of the world is wonderful to hike and explore — a stunningly beautiful country. We were also blessed with access as the area is closed to all fossil collecting except with a permit.

LATE HETTANGIAN TO EARLY SINEMURIAN FAUNA OF NEVADA

Hiking the hills of Nevada looking for David Taylor's faunal succession based on ammonoids established for the Late Hettangian to Early Sinemurian interval in the Western Cordillera.

The land here is free of trees with low only low groupings of gnarly scrub to work through to get to the bedrock below. 

Our work here was in October, which is a time when Nevada is cool in the mornings and evenings, but still surprisingly hot during the day. It is also tarantula breeding season and my first glimpse of these spiders in volume at field sites. 

It was a tremendous experience to walk through time and compare the fossil assemblages here with our own in the Canadian Rockies. Here the faunal sequence consists of one zone and four informal biochronologic units or assemblages and was outlined by Taylor as follows: Paracaloceras morganense assemblage, Badouxia oregonensis assemblage, Canadensis Zone, Metophioceras trigonatum assemblage and Coroniceras involutum. They matched up to specimens we collected over three field seasons to similar faunal outcrops of Late Hettangian to Early Sinemurian of the Last Creek and Tyaughton area of the Canadian Rockies.

The succession also correlates with the interval delineated by the Northwest European Angulata Zone through the Lyra Subzone. Two new genera (Guexiceras and Tipperoceras) are described along with 23 new species. 

The phylogenetic relationships of the earliest Jurassic ammonite superfamilies indicate that it is useful to include under the Psiloceratida, the Psilocerataceae and their derivatives including the Lytocerataceae. 

The Arietitaceae were derived from Hettangian Lytocerataceans. There is still much work to be done to work out the finer points of comparison between British Columbia's Triassic fauna and those that lived and died in what is now Nevada, USA, but enjoyable work it it.

TRACKING THROUGH THE TRIASSIC

Grambergia sp. Middle Triassic Ammonoid of  BC, Canada

In the early 1980s, Tim Tozer, Geological Survey of Canada was looking at the spread of marine invertebrate fauna in the Triassic of North America. 

In the western terranes of the Cordillera, marine faunas from southern Alaska and Yukon to Mexico are known from the parts that are obviously allochthonous with regard to the North American plates.

Lower and upper Triassic faunas of these areas, as well as some that are today up to 63 ° North, have the characteristics of the lower palaeo latitudes. In the western Cordillera, these faunas of the lower paleo latitudes can be found up to 3,000 km north of their counterparts on the American plate. This indicates a tectonic shift of significant magnitude. There are marine triads on the North American plate over 46 latitudes from California to Ellesmere Island. 

For some periods, two to three different faunal provinces can be distinguished. The differences in faunal species are linked, not surprisingly, to their palaeolatitude. They are called LPL, MPL, HPL (lower, middle, higher palaeolatitude).

Nevada provides the diagnostic features of the lower (LPL); northeastern British Columbia that of the middle (MPL) and Sverdrup Basin, the large igneous province on Axel Heiberg Island and Ellesmere Island, Nunavut, Canada near the rifted margin of the Arctic Ocean, that of the higher palaeolatitude (HPL).

A distinction between the provinces of the middle and the higher palaeo-situations can not be made for the lower Triassic and lower Middle Triassic (anise). However, all three provinces can be seen in the deposits of Ladin, Kam and Nor.

In the early 2000s, as part of a series of joint UBC, VIPS and VanPS fossil field trips (and then Chair of the VanPS), I explored much of the lower faunal outcrops of northeastern British Columbia. It was my first time seeing many of British Columbia's Triassic outcrops. Years later, and fueled by seeing paper after paper correlating the faunal assemblages of BC to those of Nevada, I had the very great pleasure of walking through the Nevada strata with John Fam (VanPS, Vice-Chair), Dan Bowen (VIPS, Chair) and Betty Franklin (VIPS, Goddess of Everything and BCPA, Treasurer) — and witnessing first-hand the correlation between the Nevada fauna and those from the Triassic of British Columbia, Canada.

Triassic ammonoids, West Humboldt Mountains, Nevada, USA

The Nevada faunal assemblages are a lovely match. The quality of preservation at localities like Fossil Hill in the Humboldt Mountains of Nevada, perhaps the most famous and important locality for the Middle Triassic (Anisian/Ladinian) of North America, is truly outstanding.

Aside from sheer beauty and spectacular preservation, the ammonoids and belemnites were tucked in cozily with very well preserved ichthyosaur remains.

Tozer's interest in our marine invert friends was their distribution. How and when did certain species migrate, cluster, evolve — and for those that were prolific, how could their occurrence — and therefore significance — aide in an assessment of plate and terrane movements that would help us to determine paleolatitudinal significance. I share a similar interest but not exclusive to our cephalopod fauna. The faunal collection of all of the invertebrates holds appeal.

Middle Triassic (Anisian/Ladinian) Fauna

This broader group held an interest for J.P. Smith who published on the marine fauna in the early 1900s based on his collecting in scree and outcrops of the West Humboldt Mountains, Nevada. He published his first monograph on North American Middle Triassic marine invertebrate fauna in 1914.

N. J. Siberling from the US Geological Survey published on these same Nevada outcrops in 1962. His work included nearly a dozen successive ammonite faunas, many of which were variants on previously described species. Both their works would inform what would become a lifelong piecing together of the Triassic puzzle for Tozer.

If one looks at the fauna and the type of sediment, the paleogeography of the Triassic can be interpreted as follows: a tectonically calm west coast of the North American plate that bordered on an open sea; in the area far from the coast, a series of volcanic archipelagos delivered sediment to the adjacent basins. Some were lined or temporarily covered with coral wadding and carbonate banks. Deeper pools were in between. The islands were probably within 30 degrees of the triadic equator. They moved away from the coast up to about 5000 km from the forerunner of the East Pacific Ridge. The geographical situation west of the back was probably similar.

Jurassic and later generations of the crust from near the back have brought some of the islands to the North American plate; some likely to South America; others have drifted west, to Asia. There are indications that New Guinea, New Caledonia and New Zealand were at a northern latitude of 30 ° or more during the Triassic period.

The terranes that now form the western Cordillera were probably welded together and reached the North American plate before the end of the Jurassic period.

Marine Triassic occurs on the North American Plate over a latitudinal spread of 46 degrees, from California to Ellesmere Island. At some intervals of time faunas on the Plate permit the discrimination of two or three provinces with distinctively different coeval faunas. The faunal differences are evidently related to paleolatitude and the provinces are designated LPL, MPL, HPL (low, mid, high paleolatitude). Nevada provides the diagnostic characters of the LPL province; northeastern British Columbia the MPL; the Sverdrup Basin the HPL. In the Lower Triassic and early Middle Triassic (Anisian), the distinction between the MPL and HPL provinces cannot be made. All three provinces are recognized in the Ladinian, Carnian and Norian deposits.

Juvavites sp. Geological Survey of Canada. Photo: John Fam

In the western tracts of the Cordillera, the part formed of suspect terranes, apparently allochthonous with respect to the North American Plate, marine faunas are known all the way from southern Alaska and Yukon to Mexico.

Lower and Upper Triassic faunas from these terranes, including some which today are at 63 degrees north, have the characters of the LPL province.

Middle Triassic faunas from the terranes, as presently known, do not contribute significant data. In the terranes of the Western Cordillera, LPL faunas were now up to 3,000 km north of their counterparts on the American Plate. Through the fossil fauna assemblages, we can see this level of tectonic displacement.

Taking into account the faunas and the nature of the rocks, the Triassic paleogeography is interpreted as a tectonically quiet west shore for the North American Plate, bordered by an open sea or ocean; then, well off-shore, a series of volcanic archipelagos shedding sediment into adjacent basins. Some were fringed or intermittently covered by coralline shoals and carbonate banks. Deeper basins were in between. The islands probably were within 30 degrees of the Triassic equator and extended offshore for about 5000 km, to the spreading ridge directly ancestral to the East Pacific Rise. The geography west of the spreading ridge was probably comparable.

Jurassic and later generation of crust at the ridge had driven some of the islands into the North American Plate; some probably to South America; others have gone west to Asia. Evidence is given that northern New Guinea, New Caledonia and New Zealand may have been at a north latitude of 30 degrees or more in the Triassic. The terranes now forming the Western Cordillera had probably amalgamated, and reached the North American Plate, before the end of the Jurassic.

At the end of the Rhaetian (part of the Triassic period), most of the ammonites had died out. The Hettangian, a rather poorly understood 3 million year time interval followed the Triassic-Jurassic mass extinction event.

During the Hettangian, the new or  Neoammonites developed quite quickly. Within a million years, a fairly large, diverse selection of genera and species had risen to fill the void. The gap created by the Triassic-Jurassic extinction event was re-filled and our ability to "read the rocks' to understand their continued movement through tectonic plate shifting recommenced.

Alsatites proaries, Hettangian Ammonite

It is during the Hettangian that the smooth shelled ammonite genus Psiloceras first appears. They span the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). For my European friends, the Hettangian is the time span in which the marine limestone, shales and clay Lias of western Europe were deposited.

This Hettangian ammonite, Alsatites proaries, is a lovely example of the cephalopods cruising our ancient oceans at that time. Alsatites is an extinct genus of cephalopod belonging to the Ammonite subclass. They lived during the Early Jurassic, Hettangian till the Sinemurian and are generally extremely evolute, many whorled with a broad keel. Or, as described by one of my very young friends, he looks like a coiled snake you make in pottery class.

The Hettangian is an interesting little period of our history. It spans the time between 201.3 ± 0.2 Ma and 199.3 ± 0.3 Ma (million years ago). For my European friends, the Hettangian is the time in which the marine limestone, shales and clay Lias of western Europe were deposited. In British Columbia, Canada, we see the most diverse middle and late Hettangian (Early Jurassic) ammonite assemblages in the Queen Charlotte Islands (Haida Gwaii), an archipelago about 50 km off British Columbia's northern Pacific coast. In total, 53 ammonite taxa are described of which Paradasyceras carteri, Franziceras kennecottense, Pleuroacanthites charlottensis, Ectocentrites pacificus and Curviceras haidae are new.

In general, North American Early Jurassic ammonites are of Tethyan affinity or endemic to the eastern Pacific. For this reason, a separate zonation for the Hettangian and Sinemurian of the Western Cordillera of North America was established. Taylor et al. (2001), wrote up and published on much of this early research though, at the time, very little Canadian information was included.

Longridge, L. M., et al. “Three New Species of the Hettangian (Early Jurassic) Ammonite Sunrisites from British Columbia, Canada.” Journal of Paleontology, vol. 82, no. 1, 2008, pp. 128–139. JSTOR, www.jstor.org/stable/20144175. Accessed 27 Jan. 2020.

Tozer, ET (Tim): Marine Triassic faunas of North America: Their significance for assessing plate and terrane movements. Geol Rundsch 71, 1077-1104 (1982). https://doi.org/10.1007/BF01821119

Danner, W. (Ted): Limestone resources of southwestern British Columbia. Montana Bur. Mines & Geol., Special publ. 74: 171-185, 1976.

Davis, G., Monger, JWH & Burchfiel, BC: Mesozoic construction of the Cordilleran “collage”, central British Columbia to central California. Pacific Coast Paleography symposium 2, Soc. Economic Paleontologists and Mineralogists, Los Angeles: 1-32, 1978.

Gibson, DW: Triassic rocks of the Rocky Mountain foothills and front ranges of northeastern British Columbia and west-central Alberta. Geol. Surv. Canada Bull. 247, 1975.

Photo of the large belemnite (Atractites sp?) and ammonites (Sunrisites & Badouxia) from the Lower Jurassic (Late Hettangian), Last Creek Formation (Castle Pass member), Taseko Lakes area, British Columbia, Canada in the collection of the deeply awesome John Fam.

Photo: A drawer of Juvavites sp. in the collections of the Geological Survey of Canada. These rarely seen Upper Triassic (Carnian to Norian) ammonoids were collected over many decades by geologists of the Geological Survey of Canada from Northeastern British Columbia. Photo care of the deeply awesome John Fam.

Photo: Grambergia sp. from the Early Anisian (Middle Triassic) ammonoid biostratigraphy of northeastern British Columbia, Canada. Collection of Fossil Huntress.

Photo: Alsatites proaries, Coll. Reiter, Neoammoniten, 30 July 2011, 19:26:10

NEVADA: AMMONOIDS AND CONODONTS

Nevada is a wonderful place to explore our palaeontological history. The state spans a broad spectrum of exposures showcasing the depth of geologic time. It is an interesting cross-section of young and old — and interestingly, a lovely comparison to the Triassic outcrops in British Columbia.

Exposures of the Upper Triassic, Early Norian, Kerri zone, Luning formation, West Union Canyon, just outside Berlin-Ichthyosaur State Park, Nevada.

The Berlin-Ichthyosaur State Park in central Nevada is a very important locality for the understanding of the Carnian-Norian boundary (CNB) in North America.

Rich ammonoid faunas from this site within the Luning Formation were studied by Silberling (1959) and provided support for the definition of the Schucherti and Macrolobatus zones of the latest Carnian, which are here overlain by well-preserved faunas of the earliest Norian Kerri Zone. Despite its importance, no further investigations have been done at this site during the last 50 years.

Jim Haggart, Mike Orchard and Paul Smith collaborated on a project that took them down to Nevada to look at the conodonts and ammonoids; the group then published a paper, "Towards the definition of the Carnian/Norian Boundary: New data on Ammonoids and Conodonts from central Nevada," which you can find in the proceedings of the 21st Canadian Paleontology Conference; by Haggart, J W (ed.); Smith, P L (ed.); Canadian Paleontology Conference Proceedings no. 9, 2011 p. 9-10.

They conducted a bed-by-bed sampling of ammonoids and conodonts in West Union Canyon during October 2010. The eastern side of the canyon provides the best record of the Macrolobatus Zone, which is represented by several beds yielding ammonoids of the Tropites group, together with Anatropites div. sp. conodont faunas from both these and higher beds are dominated by ornate 'metapolygnthids' that would formerly have been collectively referred to Metapolygnathus primitius, a species long known to straddle the CNB. Within this lower part of the section, they resemble forms that have been separated as Metapolygnathus mersinensis. Slightly higher, forms close to 'Epigondolella' orchardi and a single 'Orchardella' n. sp. occur. This association can be correlated with the latest Carnian in British Columbia.

Ammonoids of the Luning Formation

Higher in the section, the ammonoid fauna shows a sudden change and is dominated by Tropithisbites. Few tens of metres above, but slightly below the first occurrence of Norian ammonoids Guembelites jandianus and Stikinoceras, two new species of conodonts (Gen et sp. nov. A and B) appear that also occur close to the favoured Carnian/Norian boundary at Black Bear Ridge, British Columbia. Stratigraphically higher collections continue to be dominated by forms close to M. mersinensis and 'E.' orchardi.

The best exposure of the Kerri Zone is on the western side of the West Union Canyon. Ammonoids, dominated by Guembelites and Stikinoceras div. sp., have been collected from several fossil-bearing levels. Conodont faunas replicate those of the east section. The collected ammonoids fit perfectly well with the faunas described by Silberling in 1959, but they differ somewhat from the coeval faunas of the Tethys and Canada.

The genus Gonionotites, very common in the Tethys and British Columbia, is for the moment unknown in Nevada. More in general, the Upper Carnian faunas are dominated by Tropitidae, while Juvavitidae are lacking.

After years of reading about the correlation between British Columbia and Nevada, I had the very great pleasure of walking through these same sections in October 2019 with members of the Vancouver Paleontological Society and Vancouver Island Palaeontological Society. It was with that same crew that I had originally explored fossil sites in the Canadian Rockies in the early 2000s. Those early trips led to paper after paper and the exciting revelations that inspired our Nevada adventure.

LOWER PLIENSBACHIAN: ANDROGYNOCERAS

This gorgeous Lower Pliensbachian macroconch of the ammonite Androgynoceras lataecosta was found as a nodule from the Green Ammonite beds, Lower Pliensbachian, Stonebarrow Marl Member, Charmouth Mudstone Formation (190 MYA) at Charmouth Beach, Dorset Coast in the summer of 2020. 

This specimen was found, prepped and photographed by the lovely and talented folk at Stonebarrow Fossils. 

And what a delightful surprise! The large macroconch specimen here is 12 cm but is cuddled in with her is a lovely grouping of  the diminutive male microconchs of Androgynoceras (Hyatt, 1867) if you are lucky — sometimes a Tragophylloceras loscombi (Sowerby, 1814) — or nothing at all if you are not. 

We see a great variation in this species and the ammonite species that make up this population. Murray Edmunds from Chipping Norton, UK shared some of his insights on why we see such variation and how a phylogenetic species concept may be masking a continuum that tells a very different story.  

We are starting to recognise that these could all be variants of one interbreeding population — with a highly variable duration of a juvenile Capricorn stage. Palaeontologists use a phylogenetic species concept as you cannot test reproductive isolation in any but the most recent of fossils.

By definition, individuals within an interbreeding population cannot belong to different species, let alone different genera. In palaeontology, we can only interpret what we see with reference to what we understand of biology. 

In the Davoei Zone Liparoceratidae, we have a single lineage that evolves into Oistoceras. The microconchs (putative males) are small Capricorns, and the macroconchs (putative females) are very variable: they have a Capricorn juvenile stage that can be expressed for only a few mm (or not at all), or for many cm. But eventually, the adult macroconch body chamber acquires liparoceratid ornament — inflated and bipinnate with numerous secondary ribs. 

Unfortunately, the green ammonite beds at Charmouth preserve only juvenile macroconchs so we do not get to appreciate the similarity and differences of the mature adult shell form. These beauties can look very different from one another but are all the same species. 

Historically, this difference in appearance led to all the individuals — both micro and macroconchs — with prolonged Capricorn morphology being assigned to Androgynoceras and those macroconchs lacking the juvenile Capricorn stage (as is typical in their Ibex zone ancestors) to be Liparoceras. 

Different species were named for different variants. But this is a purely morphological approach to nomenclature and does not reflect the taxonomy used for extant organisms where we try to reflect phylogeny.

But as more and more examples are collected, we start to see that these specimens form a continuum. And as we follow them up through time, we see that all of them (microconchs and macroconchs, regardless of the extent of the Capricorn stage — although that tends to become more prolonged through time — simultaneously evolve progressively forwardly projected ribs across the venter, culminating in Oistoceras. 

This simultaneous evolutionary change across the entire Liparoceratid population more or less proves that we have a single interbreeding clade. And that it is separate from Becheiceras – through that’s another story! And they all go extinct simultaneously too, whereas Becheiceras carries on into the Margaritatus Zone. If you're a grad student looking to do your thesis, there is a very interesting story you could tell.

If you fancy a web stroll through some beautifully prepped specimens from Jurassic Coast, UK, or if you'd like to get some prepped, you can check out Stonebarrow Fossils here: https://www.stonebarrowfossils.co.uk/  / Photos: Stonebarrow Fossils

If you like podcasts, check out the Fossil Huntress — Palaeo Sommelier Podcast at https://anchor.fm/fossil-huntress / Spotify / Google Play / Apple Podcasts

LOVE THE WILD: MUSHROOMS OF IMMORTALITY

This glorious bit of business you see here with its showy orange and yellow colouring is a Reishi mushroom. This glorious adaptogen is known as the mushroom of immortality.

Mushrooms come in a variety of shapes, colours, sizes and edibility. Some help, some kill and many add their umami flavour to our food. 

We know mushrooms make for a delectable addition to any meal, but why are mushrooms so good for you? Mushrooms contain vital nutrients along with dietary fibre, protein and complex carbs. Eating them gives us the benefit of the goodness they contain including vitamins D and B, selenium and potassium, minerals, antioxidants, and other important micro-nutrients. 

Niacin and Copper found in mushrooms promote the function of the nervous system and keep our nerves healthy. Poetic, really, as fungi are the nervous systems of the forest. 

Mushrooms are rich in antioxidants, which helps reduce inflammation often found to be a prime suspect in neurodegeneration. Also, they’re one of the only non-animal sources of vitamin D, a component necessary for brain and neuron health.

Lion’s Mane is one variety of mushroom known to protect cognitive health. It stimulates nerve growth factor, a protein that promotes healthy brain cells. Lion’s Mane is a cognitive enhancer, and it helps creativity, motivation, and memory, as well as brain function.

Cordyceps mushrooms are reported to protect against Alzheimer’s as they prevent neuronal cell death and memory loss through its antioxidant and anti-inflammatory effects. Cordyceps are known for improving memory and promoting healthy aging.

YELLOW-BILLED KITE

This lovely boy is a Yellow-Billed Kite. The yellow-billed kite is the Afrotropic counterpart of the black kite, of which it is most often considered a subspecies. 

Their DNA studies suggest that the yellow-billed kite differs significantly from black kites in the Eurasian clade, and should be considered as a separate, allopatric species.

The yellow-billed kite is easily recognized by its entirely yellow bill, unlike that of the black kite (which is present in Africa as a visitor during the North Hemisphere winter). However, immature yellow-billed kites resemble the black kites of the corresponding age.

PLESIOSAUR: PREDATORS OF DEEP TIME

Plesiosaurus were a large, carnivorous air-breathing marine reptile with strong jaws and sharp teeth that moved through the water with four flippers. 

We had originally thought that this might not be the most aerodynamic design but it was clearly effective as they used the extra set to create a wee vortex that aided in their propulsion. 

In terms of mechanical design, they have a little something in common with an unlikely favourite of mine — dragonflies.

We have recreated plesiosaur movements and discovered that they were able to optimize propulsion to make use of their own wake. As their front flippers paddled in big circular movements, the propelled water created little whirlpools under their bellies. The back flippers would then paddle between these whirlpools pushing the plesiosaur forward to maximal effect. This use of air currents is similar to how dragonflies move through the air. 

They were very successful hunters, outcompeting ichthyosaurs who thrived in the Triassic but were replaced in the Jurassic and Cretaceous by these new aquatic beasties. 

Our ancient seas teemed with these predatory marine reptiles with their long necks and barrel-shaped bodies. Plesiosaurs were smaller than their pliosaur cousins, weighing in at about 450 kg or 1,000 lbs and reaching about 4.5 metres or 15 feet in length. For a modern comparison, they were roughly twice as long as a standard horse or about as long as a good size hippo.

Plesiosaurs first appeared in the latest Triassic, during the Rhaetian. They thrived in the Jurassic and vanished at the end of the Cretaceous in time with the K-Pg extinction event along with a host of other species. They are one of the marine reptiles that we associate with the infamous Mary Anning, a paleo darling of the early 19th century who found her first fossil specimens in the early 1800s.

SPOTTED CLEANER SHRIMP

"Wash that for you, sir?" If you were a fish living in the warm turquoise waters off the coast of Bonaire in the southern Caribbean Sea, you may not hear those words, but you'd see the shrimp sign language equivalent. It seems Periclimenes yucatanicus or the Spotted Cleaner Shrimp are doing a booming business in the local reefs by setting up a Fish Wash service.

That's right, a Fish Wash. You'd be hard-pressed to find a terrestrial Molly Maid with two opposable thumbs as studious and hardworking as this wee marine beauty. You'll find them each day cleaning and snacking on a host of parasites. As many as twenty to thirty shrimp gather together to assemble a  highly-efficient marine cleaning station. They're even open to partnerships and mergers, partnering up with Cleaner Wrasse, or cleaner fish, for larger, high-end clients.

Spotted cleaner shrimp are about 2.5 cm long and have a delightful transparent body with telltale white and brown spots. Their legs, or chelae, are striped in purple, white and red. They live about 24 metres (or 79 ft) down on the seafloor in many of our planet's most beautiful waters. Aside from the Caribbean, they also enjoy the waters off of the Bahamas, southern Florida, Panama and Columbia. They are carnivorous crustaceans in the family, Palaemonidae.

This quiet marine mogul is turning out to be one of the ocean's top entrepreneurs. Keeping its host and diet clean and green, the spotted shrimp hooks up with the locals, in this case, local sea anemones and sets up a fish wash. Picture a car wash but without the noise and teenage boys. The signage posted is the shrimps' natural colouring which attracts fish from around the reefs. They sway back and forth to indicate that they are open for business.

Wash on, wash off.

Once within reach, the shrimp cleans the surface of the fish, giving the fish a buff and the shrimp its daily feed. This is good news for the shrimp, especially this time of year as they breed and brood their eggs in summer. 

After hatching, the larvae pass through a series of sadly, tasty planktonic stages before setting up a fish wash of their own. These cuties form a solid base for the oceanic food chain. Once they are older, they gain some protection from being eaten by their clients by a special signalling system that essentially shouts, "just here IN cooperation not as food." Here's to Periclimenes for keeping up the family business.

ICHTHYOSAUR BASIOCCIPITAL BONE AND TELEOST FISH

Ichthyosaur Basioccipital Bone / Liam Langley

A very exciting find of an Ichthyosaur basioccipital bone. This is the bone next to the skull that connected to the vertebrae. He found this in situ so not very water warn as you might expect. This lovely bone was found by the deeply awesome Liam Langley on the Yorkshire Coast.

Ichthyosaurs became extinct during the Upper Cretaceous, about 30 million years before the K/T extinction event. There was an ocean anoxic event at the Cenomanian–Turonian stage boundary. The deeper layers of the seas became anoxic and poisoned by hydrogen sulphide. As life died off in the lower (benthos) levels of the sea, so did the predators at the top of the food chain. The last pliosaurs and ichthyosaurs became extinct.

Ichthyosaurs had been dwindling in numbers for some time; they were no longer the force they once were in the Upper Triassic and Lower Jurassic. By the middle Jurassic, it was thought they all belonged to the single clade, the Ophthalmosauridae. By the Cretaceous, it was thought that only three genera survived. For the last 50+ years, it has been thought that only one genus, Platypterygius, was known at the time of the anoxic event in the Upper Cretaceous.

Ichthyosaur Basioccipital Bone / Liam Langley

There was still diversity in ichthyosaurs a few million years before the extinction event. They may have survived right up to the extinction event. Ichthyosaurs had declined from their peak.

By the Cretaceous, they certainly had more competitors than in the Triassic and more elusive prey. The adaptive radiation of teleost fish meant their new prey was fast swimming and highly evasive.

The difference between teleosts and other bony fish lies mainly in their jawbones; teleosts have a movable premaxilla and corresponding modifications in the jaw musculature which make it possible for them to protrude their jaws outwards from the mouth.

This is of great advantage, enabling them to grab prey and draw it into the mouth. In more derived teleosts, the enlarged premaxilla is the main tooth-bearing bone, and the maxilla, which is attached to the lower jaw, acts as a lever, pushing and pulling the premaxilla as the mouth is opened and closed. Other bones further back in the mouth serve to grind and swallow food.

Another difference is that the upper and lower lobes of the tail (caudal) fin are about equal in size. The spine ends at the caudal peduncle, distinguishing this group from other fish in which the spine extends into the upper lobe of the tail fin.

The most basal of the living teleosts are the Elopomorpha, eels and their allies, and the Osteoglossomorpha, those whacky elephantfish and their friends. There are over 800 species of elopomorphs; each with thin leaf-shaped larvae known as leptocephali specialized for a marine environment.

Among the elopomorphs, eels have elongated bodies with lost pelvic girdles and ribs and fused elements in the upper jaw. The 200 species of osteoglossomorphs are defined by a bony element in the tongue. This element has a basibranchial behind it, and both structures have large teeth that are paired with the teeth on the parasphenoid in the roof of the mouth.

The clade Otocephala includes the Clupeiformes, tasty herrings, and Ostariophysi  — carp, catfish and their friends. Clupeiformes are made up of 350 living species of herring and herring-like fish. This group is characterized by an unusual abdominal scute and a different arrangement of the hypurals. In most species, the swim bladder extends to the braincase and plays a role in hearing. Ostariophysi, which includes most freshwater fishes, has developed some unique adaptations.

One is the Weberian apparatus, an arrangement of bones, called Weberian ossicles, connecting the swim bladder to the inner ear. This enhances their hearing, as sound waves make the bladder vibrate, and the bones transport the vibrations to the inner ear. They also have a chemical alarm system; when a fish is injured, the warning substance gets in the water, alarming nearby fish. Excellent for the predatory fish, less so for their poor injured brethren.

The teleosts included fast-swimming predatory fish, which would have been competing for similar food resources to our ichthyosaur friends. Had they complained about the teleosts they would have been deeply aghast to know what was coming next — big, hungry mosasaurs. The ichthyosaurs and pliosaurs were replaced in the marine ecology by the giant mosasaurs. The mosasaurs were probably ambush-hunters, whose sit-and-wait strategy apparently proved most successful. So, teleost fish, the ocean anoxic event and the rise of mosasaurs all contributed to the end of the ichthyosaurs.

Photos 1-2: By the awesome Liam Langley
Image 3: By Sir Francis Day - Fauna of British India, Fishes (www.archive.org), Public Domain, https://commons.wikimedia.org/w/index.php?curid=1919094

LOPHIIFORMES: ANGLERFISH

Humpback Anglerfish, Melanocetus johnsonii

The festive lassie you see here with her toothy grin and solo birthday-candle-style light is an Anglerfish.

They are bony fish of the teleost order Lophiiformes (Garman, 1899) and one of the most interesting, intriguing yet creepy, species on this planet.

There are over 200 species of anglerfish, most living in the pitch-black depths of the Atlantic and Antarctic oceans. They always look to be celebrating a birthday of some kind, albeit solo. This party is happening deep in our oceans right now and for those that join in, I hope they like it rough. The wee candle you see on her forehead is a photophore, a tiny bit of luminous dorsal spine. Many of our sea dwellers have photophores. We see them in glowing around the eyes of some cephalopods.

These light organs can be a simple grouping of photogenic cells or more complex with light reflectors, lenses, colour filters able to adjust the intensity or angular distribution of the light they produce. Some species have adapted their photophores to avoid being eaten, in others, it's an invitation to lunch but not in the traditional sense of that invite. In the anglerfish' world, it's dead sexy, an adaptation used to attract prey and mates alike, sometimes at the same time.

Deep in the murky depths of the Atlantic and Antarctic oceans, hopeful female anglerfish light up their sexy lures. When a male latches onto this tasty bit of flesh, he fuses himself totally.

He might be one of several potential mates. Each will take a turn getting close to her to see if she's the one. For her, it's not much of a choice. She's not picky, just hungry.

Mating is a tough business down in the depths. A friend asked if anglerfish mate for life. Well, yes... yes, indeed they do. Lure. Feed. Mate. Repeat. Once connected, the attachment is permanent. Her body absorbs his over time until all that's left are his testes. While unusual, it is only one of many weird and whacky ways our fishy friends communicate, entice, hunt and creatively survive and thrive. Ah, this planet has some evolutionary adaptations that are enough to break your brain. Anglerfish are definitely in with that lot.

VICTORASPIS LONGCORNUALIS

This lovely specimen, showing both the positive and negative of the fossil, is an armoured agnatha jawless bony fish, Victoraspis longicornualis, from Lower Devonian deposits of Podolia, Ukraine.

Podolia is a historic region in Eastern Europe in the west-central and south-western parts of the Ukraine. This area has had human inhabitants since at least the beginning of the Neolithic period. 

Herodotus mentions it as the seat of the Graeco-Scythian Alazones and possibly Scythian Neuri. Subsequently, the Dacians and the Getae arrived. The Romans left traces of their rule in Trajan's Wall, which stretches through the modern districts of Kamianets-Podilskyi, Nova Ushytsia and Khmelnytskyi.

During the Great Migration Period, many nationalities passed through this territory or settled within it for some time, leaving numerous traces in archaeological remains. Nestor in the Primary Chronicle mentions four apparently Slavic tribes: the Buzhans and Dulebes along the Southern Bug River, and the Tivertsi and Ulichs along the Dniester. The Avars invaded in the 7th century. The Bolokhoveni occupied the same territory in Early Medieval times but they were mentioned in chronicles only until the 14th century.

And, as you can see here, it boasts some wonderful Devonian deposits. Victoraspis longicornualis was named by Anders Carlsson and Henning Bloom back in 2008. The new osteostracan genus and species were described based on material from Rakovets' present-day Ukraine. This new taxon shares characteristics with the two genera Stensiopelta (Denison, 1951) and Zychaspis (Javier, 1985).

Agnatha is a superclass of vertebrates. This fellow looks quite different from our modern Agnatha, which includes lamprey and hagfish. Ironically, hagfish are vertebrates that do not have vertebrae. Sometime in their evolution, they lost them as they adapted to their environment. Photo: Fossilero Fisherman

MANATEES OF TEXAS

Manatees do not live year-round in Texas, but these gentle sea cows are known to occasionally visit, swimming in for a 'summer vacation' and returning to warmer waters for the winter. New research has found fossil evidence for manatees along the Texas coast dating back to the most recent ice age. 

The discovery raises questions about whether manatees have been visiting for thousands of years, or if an ancient population of ice age manatees once called Texas home somewhere between 11,000 and 240,000 years ago.

The findings were published in Palaeontologia Electronica by lead author Christopher Bell, a professor at the UT Jackson School of Geosciences with co-authors Sam Houston State University Natural History Collections curator William Godwin and SHSU alumna Kelsey Jenkins — now a graduate student at Yale University — and SHSU Professor Patrick Lewis.

The eight fossils described in the paper include manatee jawbones and rib fragments from the Pleistocene, the geological epoch of the last ice age. Most of the bones were collected from McFaddin Beach near Port Arthur and Caplen Beach near Galveston during the past 50 years by amateur fossil collectors who donated their finds to the SHSU collections.

The Jackson Museum of Earth History at UT holds two of the specimens. A lower jawbone fossil, which was donated to the SHSU collections by amateur collector Joe Liggio, jumpstarted the research.

Manatee jawbones have a distinct S-shaped curve that immediately caught Godwin's eye. But Godwin said he was met with scepticism when he sought other manatee fossils for comparison. He recalls reaching out to a fossil seller who told him point-blank "there are no Pleistocene manatees in Texas."

But an examination of the fossils by Bell and Lewis proved otherwise. The bones belonged to the same species of manatee that visits the Texas coast today, Trichechus manatus. An upper jawbone donated by U.S. Rep. Brian Babin was found to belong to an extinct form of the manatee, Trichechus manatus bakerorum.

The age of the manatee fossils is based on their association with better-known ice age fossils and paleo-Indian artefacts that have been found on the same beaches.

It's assumed that the cooler ice age climate would have made Texas waters even less hospitable to manatees than they are today. But the fact that manatees were in Texas — whether as visitors or residents — raises questions about the ancient environment and ancient manatees. The Texas coast stretched much farther into the Gulf of Mexico and hosted wider river outlets during the ice age than it does today. Either the coastal climate was warmer than is generally thought, or ice age manatees were more resilient to cooler temperatures than manatees of today.

Subsurface imaging of the now flooded modern continental shelf reveals both a greater number of coastal embayments and the presence of significantly wider channels during ice age times.

If there was a population of ice age manatees in Texas, it's plausible that they would have ridden out winters in these warmer river outlets similar to how they do today in Florida and Mexico.

Reference: Christopher Bell, William Godwin, Kelsey Jenkins, Patrick Lewis. First fossil manatees in Texas: Trichechus manatus bakerorum in the Pleistocene fauna from beach deposits along the Texas Coast of the Gulf of Mexico. Palaeontologia Electronica, 2020; DOI: 10.26879/1006

DUGONGIDAE: STELLAR SEA COW

One of the most delightful creatures to ever grace this planet is the dugong — a species of sea cow found throughout the warm latitudes of the Indian and western Pacific Oceans. 

It is one of four living species of the order Sirenia, which also includes three species of manatees — their large, fully aquatic, mostly herbivorous marine mammal cousins.

The closest living relatives of sirenians are elephants. Manatees evolved from the same land animals as elephants over 50 million years ago. If not for natural selection, we might have a much more diverse showing of the Sirenia as their fossil lineage shows a much more diverse group of sirenians back in the Eocene than we have today. It is the only living representative of the once-diverse family Dugongidae; its closest modern relative, Steller's sea cow, was hunted to extinction in the 18th century. 

While only one species of the dugong is alive today – a second, the Steller's sea cow only left this Earth a few years ago. Sadly, it was hunted to extinction within 27 years of its discovery – about 30 species have been recovered in the fossil record

The first appearance of sirenians in the fossil record was during the early Eocene, and by the late Eocene, sirenians had significantly diversified. Inhabitants of rivers, estuaries, and nearshore marine waters, they were able to spread rapidly.

The most primitive sirenian known to date, Prorastomus, was found in Jamaica, not the Old World; however, more recently the contemporary Sobrarbesiren has been recovered from Spain. The first known quadrupedal sirenian was Pezosiren from the early Eocene. The earliest known sea cows, of the families Prorastomidae and Protosirenidae, are both confined to the Eocene and were about the size of a pig, four-legged amphibious creatures. By the time the Eocene drew to a close, the Dugongidae had arrived; sirenians had acquired their familiar fully aquatic streamlined body with flipper-like front legs with no hind limbs, powerful tail with horizontal caudal fin, with up and down movements which move them through the water, like cetaceans.

The last of the sirenian families to appear, Trichechidae, apparently arose from early dugongids in the late Eocene or early Oligocene. The current fossil record documents all major stages in hindlimb and pelvic reduction to the extreme reduction in the modern manatee pelvis, providing an example of dramatic morphological change among fossil vertebrates.

Since sirenians first evolved, they have been herbivores, depending on seagrasses and aquatic angiosperms, tasty flowering plants of the sea, for food. To the present, almost all have remained tropical (with the notable exception of Steller's Sea Cow), marine, and angiosperm consumers. Sea cows are shallow divers with large lungs. They have heavy skeletons to help them stay submerged; the bones are pachyostotic (swollen) and osteosclerotic (dense), especially the ribs which are often found as fossils.

Eocene sirenians, like Mesozoic mammals but in contrast to other Cenozoic ones, have five instead of four premolars, giving them a 3.1.5.3 dental formula. Whether this condition is truly primitive retention in sirenians is still under debate.

Although cheek teeth are relied on for identifying species in other mammals, they do not vary to a significant degree among sirenians in their morphology but are almost always low-crowned —brachyodont — with two rows of large, rounded cusps — bunobilophodont. The most easily identifiable parts of sirenian skeletons are the skull and mandible, especially the frontal and other skull bones. With the exception of a pair of tusk-like first upper incisors present in most species, front teeth — incisors and canines — are lacking in all, except the earliest sirenians.

ICHTHYOSAURS, SHARKS AND BLUBBER

We've learned much about the mighty ichthyosaur since first discovering their bones in Wales back in 1699. That's over three hundred years of knowledge.

We have classified them as an extinct order of marine reptiles from the Mesozoic era. We know that they were visibly dolphin-like in appearance and share some other qualities as well. They were warm-blooded, used their colouration as camouflage and had insulating blubber to keep them warm.

Ichthyosaurs are interesting because they have many traits in common with dolphins, but are not at all closely related to those sea-dwelling mammals. We aren't exactly sure of their biology either. They have many features in common with living marine reptiles like sea turtles, but we know from the fossil record that they gave live birth, which is associated with warm-bloodedness. This study reveals some of those biological mysteries.

We find their fossil remains in outcrops spanning the mid-Cretaceous to the earliest Triassic. As we look through the fossils, we see a slow evolution in body design moving towards that enjoyed by dolphins and tuna by the Upper Triassic, albeit with a narrower, more pointed snout.

Johan Lindgren, Associate Professor at Sweden's Lund University and lead author on the paper,  described the 180 million-year-old specimen, Stenopterygius, from outcrops in the Holzmaden quarry in Germany.

Both the body outline and remnants of internal organs are clearly visible in the specimen. Remarkably, the fossil is so well-preserved that it is possible to observe individual cellular layers within its skin.

Stenopterygius quadriscissus

Researchers identified cell-like microstructures containing pigment organelles on the surface of the fossil.

This ancient skin revealed a feature we recognized from marine dwelling animals, the ability to change colour, providing camouflage from potential predators. They also found traces of what might have been the animal's liver.

When they put some of the tissue through chemical analysis, it was consistent with what we'd look for in adipose tissue or blubber. Not surprising as dolphins today use blubber for buoyancy and to help to thermally insulate for thermal regulation in cold seas. It's a highly useful adaptation and one that led me to wonder what other vertebrates might use blubber or some other adaptation to maintain a warmer body temperature independent of icy cold conditions.

Today, blubber is an important part of the anatomy of seals, walruses and whales. It covers the core of their bodies, storing energy, insulating them from cold seas and providing extra buoyancy. 

A rather fetching Walrus, Odobenus rosmarus

Fat and blubber are not the same. The main differences are their consistency and blood supply —  blubber contains many more blood vessels than fat, and is far denser because it's made up of a mix of collagen fibres and lipids.

Blubber layers can be incredibly thick. Walruses deposit most of their body fat into a thick layer of blubber — a layer of fat reinforced by fibrous connective tissue that lies just below the skin of most marine mammals.

This blubber layer insulates the walrus and streamlines its body. It also functions as an energy reserve. Blubber covers the core of their bodies but does not grace their fins, flippers and flukes.

Not all marine animals need blubber. Our cold-blooded marine friends: sharks, crabs, fish, are able to let their body temperatures dropdown to very chilly levels, some as low as 36 degrees Fahrenheit.

They have a few tricks up their sleeves to make this happen. Sharks have evolved specialized physiology to keep their metabolic rate high and their hearts are able to contract in the icy depths because of a special protein. These adaptations allow sharks to enjoy a wide range of habitats and follow their food from warm tropical seas to the icy waters of the North Pacific.

Gray Shark, Carcharhinus amblyrhynchos

With the advent of genetics, we've now learned that the Great White Shark’s genetic code and many of the proteins they use to control metabolism are more closely related to humans than zebrafish, the quintessential fish model.

In a very cool bit of science, researchers sequenced a shark's heart transcriptome – the messenger molecules produced from the shark’s genome, including those active in making proteins. Then they categorized the proteins based on their functions.

What they found that the proportions of white shark proteins in many categories matched humans more closely than zebrafish. Of particular interest was that white shark had a closer match to humans for proteins involved in metabolism. Great White Sharks have a rare trait in fish called regional endothermy. This allows them to keep the body temperature of some of their organs warmer than the ambient water — a highly useful trait for fast swimming, digestion and hunting in colder waters.

References and additional reading:

Fancy a read? Check out the work by Michael Stanhope, professor of evolutionary genomics at Cornell’s College of Veterinary Medicine, and scientists at the Save Our Seas Shark Research Center at Nova Southeastern University (NSU). He published the shark genetic study in the November 2013 issue of BMC Genomics. It lays the foundation for genomic exploration of sharks and vastly expands genetic tools for their conservation.

Johan Lindgren, Peter Sjövall, Volker Thiel, Wenxia Zheng, Shosuke Ito, Kazumasa Wakamatsu, Rolf Hauff, Benjamin P. Kear, Anders Engdahl, Carl Alwmark, Mats E. Eriksson, Martin Jarenmark, Sven Sachs, Per E. Ahlberg, Federica Marone, Takeo Kuriyama, Ola Gustafsson, Per Malmberg, Aurélien Thomen, Irene Rodríguez-Meizoso, Per Uvdal, Makoto Ojika, Mary H. Schweitzer. Soft-tissue evidence for homeothermy and crypsis in a Jurassic ichthyosaur. Nature, 2018; DOI: 10.1038/s41586-018-0775-x

North Carolina State University. (2018, December 5). Soft tissue shows Jurassic ichthyosaur was warm-blooded, had blubber and camouflage. ScienceDaily. Retrieved September 7, 2019, from www.sciencedaily.com/releases/2018/12/181205134118.htm

Photo: By Haplochromis - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=5825284