Tuesday, 30 April 2019


This well-preserved partial ichthyosaur was found in the Blue Lias shales by Lewis Winchester-Ellis in 2018. An exciting find to be sure. The vertebrae you see are from the tail section of this marine reptile.

The find includes stomach contents which tell us a little about how this particular fellow liked to dine.

As with most of his brethren, he enjoyed fish and cephalopods. Lewis found fishbone and squid tentacle hooklets in his belly. Oh yes, these ancient cephies had grasping hooklets on their tentacles. I'm picturing them wiggling all ominously. The hooklets were the only hard parts of the animal preserved in this case as the softer parts of this ancient calamari were fully or partially digested before this ichthyosaur met his end.

Ichthyosaurus was an extinct marine reptile first described from fossil fragments found in 1699 in Wales. Shortly thereafter, fossil vertebrae were published in 1708 from the Lower Jurassic and the first member of the order Ichthyosauria to be discovered.

To give that a bit of historical significance, this was the age of James Stuart, Jacobite hopeful to the British throne. While scientific journals of the day were publishing the first vertebrae ichthyosaur finds, he was avoiding the French fleet in the Firth of Forth off Scotland. This wasn’t Bonnie Prince Charlie, this was his Dad. Yes, that far back.

The first complete skeleton was discovered in the early 19th century by Mary Anning & her brother Joseph along the Dorset Jurassic Coast. Joseph had mistakenly, but quite reasonably, taken the find for an ancient crocodile. Mary excavated the specimen a year later and it was this and others that she found that would supply the research base others would soon publish on.

Mary's find was described by a British surgeon, Sir Everard Home, an elected Fellow of the Royal Society, in 1814. The specimen is now on display at the Natural History Museum in London bearing the name Temnodontosaurus platyodon, or “cutting-tooth lizard.”

In 1821, William Conybeare and Henry De La Beche, a friend of Mary's, published a paper describing three new species of unknown marine reptiles based on the Anning's finds.

The Rev. William Buckland would go on to describe two small ichthyosaurs from the Lias of Lyme Regis, Ichthyosaurus communis and Ichthyosaurus intermedius, in 1837.

Remarkable, you'll recall that he was a theologian, geologist, palaeontologist AND Dean of Westminster. It was Buckland who published the first full account of a dinosaur in 1824, coining the name, "Megalosaurus."

The Age of Dinosaurs and Era of the Mighty Marine Reptile had begun.

Ichthyosaurs have been collected in the Blue Lias near Lyme Regis and the Black Ven Marls. More recently, specimens have been collected from the higher succession near Seatown. Paddy Howe, Lyme Regis Museum geologist, found a rather nice Ichthyosaurus breviceps skull a few years back. A landslip in 2008 unveiled some ribs poking out of the Church cliffs and a bit of digging revealed the ninth fossil skull ever found of a breviceps, with teeth and paddles to boot.

Specimens have since been found in Europe in Belgium, England, Germany, Switzerland and in Indonesia. Many tremendously well-preserved specimens come from the limestone quarries in Holzmaden, southern Germany.

Ichthyosaurs ranged from quite small, just a foot or two, to well over twenty-six metres in length and resembled both modern fish and dolphins.

Dean Lomax and Sven Sachs, both active (and delightful) vertebrate paleontologists, have described a colossal beast, Shonisaurus sikanniensis from the Upper Triassic (Norian) Pardonet Formation of northeastern British Columbia, Canada, measuring 3-3.5 meters in length. The specimen is now on display in the Royal Tyrrell Museum of Palaeontology in Alberta, Canada. It was this discovery that tipped the balance in the vote, making it British Columbia's Official Fossil. Ichthyosaurs have been found at other sites in British Columbia, on Vancouver Island and the Queen Charlotte Islands (Haida Gwaii) but Shoni tipped the ballot.

The first specimens of Shonisaurus were found in the 1990s by Peter Langham at Doniford Bay on the Somerset coast of England.

Dr. Betsy Nicholls, Rolex Laureate Vertebrate Palaeontologist from the Royal Tyrrell Museum, excavated the type specimen of Shonisaurus sikanniensis over three field sessions in one of the most ambitious fossil excavations ever ventured. Her efforts from 1999 through 2001, both in the field and lobbying back at home, paid off. Betsy published on this new species in 2004, the culmination of her life’s work and her last paper as we lost her to cancer in autumn of that year.

Charmingly, Betsy had a mail correspondence with Roy Chapman Andrews, former director of the American Museum of Natural History, going back to the late 1950s as she explored her potential career in palaeontology. Do you recall the AMNH’s sexy paleo photos of expeditions to the Gobi Desert in southern Mongolia in China in the early 20th century? You’d remember if you’d seen them. Roy Chapman Andrews was the lead on that trip. His photos are what fueled the flames of my own interest in paleo.

We've found at least 37 specimens of Shonisaurus in Triassic outcrops of the Luning Formation in the Shoshone Mountains of Nevada, USA. The finds go back to the 1920s. The specimens that may it to publication were collected by M. Wheat and C. L. Camp in the 1950s.  The aptly named Shonisaurus popularis became the Nevada State Fossil in 1984. Our Shoni got around. Isolated remains have been found in a section of sandstone in Belluno, in the Eastern Dolomites, Veneto region of northeastern Italy. The specimens were published by Vecchia et al. in 2002.

For a time, Shonisaurus was the largest ichthyosaurus known.

Move over, Shoni, as a new marine reptile find competes with the Green Anaconda (Eunectes murinus) and the Blue Whale (Balaenoptera musculus) for size at a whopping twenty-six (26) metres.

The find is the prize of fossil collector turned co-author, Paul de la Salle, who (you guessed it) found it in the lower part of the intertidal area that outcrops strata from the latest Triassic Westbury Mudstone Formation of Lilstock on the Somerset coast. He contacted Dean Lomax and Judy Massare who became co-authors on the paper.

The find and conclusions from their paper put "dinosaur" bones from the historic Westbury Mudstone Formation of Aust Cliff, Gloucestershire, UK site into full reinterpretation.

And remember that ichthyosaur the good Reverend Buckland described back in 1837, the Ichthyosaurus communis? Dean Lomax was the first to describe a wee baby. A wee baby ichthyosaur! Awe. I know, right? He and paleontologist Nigel Larkin published this adorable first in the journal of Historical Biology in 2017.

They had teamed up previously on another first back in 2014 when they completed the reconstruction of an entire large marine reptile skull and mandible in 3-D, then graciously making it available to fellow researchers and the public. The skull and braincase in question were from an Early Jurassic, and relatively rare, Protoichthyosaurus prostaxalis. The specimen had been unearthed in Warwickshire back in the 1950's. Unlike most ichthyosaur finds of this age it was not compressed and allowed the team to look at a 3-D specimen through the lens of computerised tomography (CT) scanning.

Another superb 3-D ichthyosaur skull was found near Lyme Regis by fossil hunter-turned-entrepreneur-local David Sole and prepped by the late David Costain. I'm rather hoping it went into a museum collection as it would be wonderful to see the specimen studied, imaged, scanned and 3-D printed for all to share. Here's hoping.

Lomax and Sven Sachs also published on an embryo from one of the largest ichthyosaurs known, a new species named Ichthyosaurus somersetensis. Their paper in the ACTA Palaeontologica Polonica from 2017, describes the third embryo known for Ichthyosaurus and the first to be positively identified to species level. The specimen was the collected from the Lower Jurassic strata (lower Hettangian, Blue Lias Formation) of Doniford Bay, Somerset, UK and is housed in the collection of the Niedersächsisches Landesmuseum (Lower Saxony State Museum) in Hannover, Germany.

We've learned a lot about them in the time we've been studying them. We now have thousands of specimens, some whole, some as bits and pieces. Many specimens that have been collected are only just now being studied and the tools we are using to study them are getting better and better.

While they resembled fish and dolphins, Ichthyosaurs were large marine reptiles belonging to the order known as Ichthyosauria or Ichthyopterygia. In 2018, Benjamin Kear and his team were able to study ichthyosaur remains at the molecular level, Their findings suggest ichthyosaurs had skin and blubber quite similar to our modern dolphins.

While ichthyosaurs evolved from land-dwelling, lung-breathing reptiles, they returned to our ancient seas and evolved into the fish-shaped creatures we find in the fossil record today.

Their limbs fully transformed into flippers, sometimes containing a very large number of digits and phalanges. Their flippers tell us they were entirely aquatic as they were not well-designed for use on land. And it was their flippers that first gave us the clue that they gave birth to live young; a find later confirmed by fossil embryo and wee baby ichy finds.

They thrived during much of the Mesozoic era; based on fossil evidence, they first appeared around 250 million years ago (Ma) and at least one species survived until about 90 million years ago into the Late Cretaceous.

During the early Triassic period, ichthyosaurs evolved from a group of unidentified land reptiles that returned to the sea. They were particularly abundant in the later Triassic and early Jurassic periods before being replaced as premier aquatic predator by another marine reptilian group, the Plesiosauria, in the later Jurassic and Cretaceous periods.

In the Late Cretaceous, ichthyosaurs were hard hit by the Cenomanian-Turonian anoxic event. As the deepest benthos layers of the seas became anoxic, poisoned by hydrogen sulphide, deep water marine life died off. This caused a cascade that wreaked havoc all the way up the food chain. At the end of that chain were our mighty predaceous marine reptiles.

Bounty turned to scarcity and a race for survival began. The ichthyosaurs lost that race as the last lineage became extinct. It may have been their conservative evolution as a genus when faced with a need for adaptation to the world in which they found themselves and/or being outcompeted by early mosasaurs.

There are promising discoveries coming out of strata from the Cretaceous epeiric seas of Texas, USA from Nathan E. Van Vranken

His published paper from 2017, "An overview of ichthyosaurian remains from the Cretaceous of Texas, USA," looks at ichthyosaurian taxa from the mid-Cretaceous (Albian–Cenomanian) time interval in North America with an eye to ichthyosaurian distribution and demise.

The find and photos are all credited to Lewis Winchester-Ellis. Thank you for sharing your tremendous specimen with us. Lewis did much of the preparation of the specimen, removing the majority of the matrix. The spectacular final prep is credited to Lizzie Hingley, Stonebarrow Fossils, Oxfordshire. Her skill with an air scribe is unparalleled.

Link to Lomax Paper: https://journals.plos.org/plosone/article…

Link to Nathan's Paper: https://www.tandfonline.com/…/10.1080/03115518.2018.1523462…

Nicholls Paper: E. L. Nicholls and M. Manabe. 2004. Giant ichthyosaurs of the Triassic - a new species of Shonisaurus from the Pardonet Formation (Norian: Late Triassic) of British Columbia. Journal of Vertebrate Paleontology 24(4):838-849 [M. Carrano/H. Street]

Monday, 29 April 2019


Coleman Shrimp / Periclimenes colemani
These daring lovelies are Coleman shrimp, Periclimenes colemani. They are generally found in mating pairs atop the exquisitely beautiful but frightfully poisonous, Fire Sea Urchin, Asthenosoma varium.

The female of the Coleman pair in this photo is the slightly larger beauty on the left. She's looking poised and ready to catch something tasty with her open claws. Coleman shrimp and several other fish and invertebrates were named after the Australian naturalist and underwater nature photographer, Neville Coleman. It was his life's mission to document all of the sea life of Australia. 

Sunday, 28 April 2019

Saturday, 27 April 2019


Moon Jelly Fish / Aurelia Aurita

Friday, 26 April 2019


This braw fellow is Ceratiocaris papilio (Salter in Murchison, 1859) a pod Shrimp from the Silurian mudstones of the Kip Burn Formation in the Midland Valley of Scotland. He would have swam in rising seas filled with crinoids, coral reefs, brachiopods, trilobites and new and exotic fish -- some sporting jaws for the first time.

Ceratiocaris is a genus of extinct paleozoic phyllocarid crustacean whose fossils are found in marine strata from the Upper Ordovician through to the Silurian.

They are typified by eight short thoracic segments, seven longer abdominal somites and an elongated pretelson somite. Their carapace is slightly oval shaped; they have many ridges parallel to the ventral margin and possess a horn at the anterior end.

This tidy specimen is from the Silurian mudstones that characterise the Kip Burn Formation with it's dark laminated silty bands. The lower part of the Kip Burn houses the highly fossiliferous ‘Ceratiocaris beds’, that yield the arthropods Ceratiocaris, Dictyocaris, Pterygotus, Slimonia and the fish Birkenia and Thelodus.

The upper part of the formation, the ‘Pterygotus beds’, contain abundant eurypterid fauna together with the brachiopods Lingula and Ceratiocaris. The faunas in the Kip Burn Formation reflect the start of the transition from marine to quasi- or non-marine conditions in the group.

Ceratiocaris are also well known from the Silurian Eramosa Formation of Ontario, Canada (which also has rather nice eurypterids). Photo credit / collection of: York Yuxi Wang and Tianyi Zhang

Joseph H. Collette; David M. Rudkin (2010). "Phyllocarid crustaceans from the Silurian Eramosa Lagerstätte (Ontario, Canada): taxonomy and functional morphology". Journal of Paleontology. 84 (1): 118–127. doi:10.1666/08-174.1.

M. Copeland; T. E. Bolton (1985). Fossils of Ontario part 3: the eurypterids and phyllocarids. Volume 48 of Life Sciences Miscellaneous Publications. Royal Ontario Museum. ISBN 0-88854-314-X.

Thursday, 25 April 2019


Horsefly / Diptera / Tabanidae; Latreille, 1802
Horseflies are true flies in the family Tabanidae, order Diptera. They are quite large as flies go and adept little aviators. If you've had the pleasure you'd recall meeting them as they have a nasty bite when they do. It's the female horseflies that do the chomping, preferring livestock and the occasional human as they hike or enjoy the great outdoors. Horseflies are sun lovers, they are out in force on nice sunny days and set a healthy bedtime as they become inactive and rest when the sun goes down.

Wednesday, 24 April 2019


Wee Eocene Snout Weevil / Photo: Jim Barkley
A lovely fossil Snout Weevil, family Curculionidae, from the Green River Formation of Western Colorado, USA.

This fellow is from the collection of the deeply awesome Jim Barkley. He gets credit for the lovely photography, too, which shows the exquisite detail on this specimen.

Fossil weevil specimens can be found in the Eocene Green River Formation that outcrops in Wyoming, Colorado and Utah. The Formation is famous for its diverse faunal and floral assemblage of fossils and its fish in particular.

The site boasts beautifully preserved fossil stromatolites, plants, invertebrates and vertebrates. Specimens include reptiles, a broad selection of mammals and, surprise, even primates!

Weevils are herbivorous beetles. They're what your Mamma would call, "good little eaters." And there are plenty of them. The Curculionidae is the family of the "true" weevils and is one of the largest animal families. We likely still haven't met them all. A family reunion would include 6,800 genera and 83,000 species at last count. But don't place your final catering order just yet. If we include all the closely related weevil-type beetles in the superfamily Curculionoidea, we'd have to include an additional ten families. Quadruple that catering menu.

Weevils look like little tiny anteaters with a long 'snout' or rostrum, at the front of their head. Some of the members of this family have rather poor reputations as they make a living by damaging plants of interest to us humans.

Topping the hugely unpopular list is the boll weevil, Anthonomus grandis, a native of Mexico (until it's US invasion in 1892) and famous destroyer of cotton crops.

The Ips genus, feeding on Ponderosa pine, introduces a fungus to the tree. The fungus blocks resin canals, which leaves the weevil free to eat. Resin would normally wash the insects out; it is a defence mechanism. The fungus often kills the tree, and groups of dead trees are a focus for forest fires. In this way the insect is indirectly responsible for serious fires. The maize weevil, Sitophilus zeamais, is a major pest. It attacks both standing crops and stored cereal products, including wheat, rice, sorghum, oats, barley, rye, buckwheat, peas, and cottonseed.

Tuesday, 23 April 2019


More than a 100 groups of mammals and a wide variety of plants have been found in the early Miocene, 39-19 million year old, John Day Formation near Kimberly, Oregon. The fossiliferous strata that have yielded beautifully preserved specimens of many of the animals we see domesticated today.

Dogs, cats, swine and horses are common. Oreodonts, camels, rhinoceros and rodents have also been found in this ancient deciduous forested area.

Here my talented young paleontologist cousin Spencer is holding a well preserved Oreodont skull.Many sites in Oregon yield beautifully preserved fossil shells laid down over 60 million years.
The asteroid that hit the Gulf of Mexico at the end of the Cretaceous caused a seafloor rift that split ancient Oregon. The massive hole left behind as the coastal lands slid northward filled in with sediment, refilling the basin.

These marine sediments were uplifted around the time of the birth of Oregon's Coastal Range. Easily collected and identified, as they look very similar to their modern cousins, you can dig for marine fossils all along Oregon's beachfront. I'll post some photos when I return from collecting later this year.

Monday, 22 April 2019

Sunday, 21 April 2019


An amazing mummified tilefish, Branchiostegus japonicus (Houttuyn, 1782) from Holocene deposits near Shizuoka, Japan. This specimen shows remarkable detail right down to the scales. Quite spectacular, truly.

Modern cousins of this fellow live as far south as the Arafura Sea today. Collection and photos from the deeply awesome Takashi Ito. サンさん、ありがとうございました

Friday, 19 April 2019


Bristolia insolens
A stunning Cambrian trilobite, Bristolia insolens, from Frenchman Mountain near Las Vegas, Nevada.

The mountain provides an example of the Great unconformity with the tilted Paleozoic Tapeats Sandstone underlain by Paleoproterozoic Vishnu Schist. An unconformity is a buried erosional or non-depositional surface separating two strata of different ages. We know when we find these that the sediment was not laid down in a continuous deposition. The range also boasts some of the oldest rock on the North American continent, at about two billion years old.

This spectacular specimen is in the collection of York Yuxi Wang. It is about 4-5cm long; 3-4cm wide.

Thursday, 18 April 2019

Wednesday, 17 April 2019


Gastropods, or univalves, are the largest and most successful class of molluscs. They started as exclusively marine but have adapted well and now their rank spend more time in freshwater than in salty marine environments.

Many are marine, but two thirds off all living species live in freshwater or on land. Their entry into the fossil record goes all the way back to the Cambrian.

Slugs and snails, abalones, limpets, cowries, conches, top shells, whelks, and sea slugs are all gastropods. They are the second largest class of animals with over 60,000–75,000 known living species.

The gastropods are originally sea-floor predators, though they have evolved to live happily in many other habitats. Many lines living today evolved in the Mesozoic. The first gastropods were exclusively marine and appeared in the Upper Cambrian (Chippewaella, Strepsodiscus).

By the Ordovician, gastropods were a varied group present in a variety of aquatic habitats. Commonly, fossil gastropods from the rocks of the early Palaeozoic era are too poorly preserved for accurate identification. Still, the Silurian genus Poleumita contains fifteen identified species.

Most of the gastropods of the Palaeozoic era belong to primitive groups, a few of which still survive today. By the Carboniferous period many of the shapes we see in living gastropods can be matched in the fossil record, but despite these similarities in appearance the majority of these older forms are not directly related to living forms. It was during the Mesozoic era that the ancestors of many of the living gastropods evolved.

In rocks of the Mesozoic era gastropods are more common as fossils and their shell often very well preserved. While not all gastropods have shells, the ones that do fossilize more easily and consequently, we know a lot more about them. We find them in fossil beds from both freshwater and marine environments, in ancient building materials and as modern guests of our gardens.

Tuesday, 16 April 2019

Sunday, 14 April 2019


This lovely specimen is Zeacrinites magnoliaeformis, an Upper Mississippian-Chesterian crinoid found by Keith Metts in the Glen Dean Formation, Grayson County, Kentucky, USA.

Crinoids are unusually beautiful and graceful members of the phylum Echinodermata. They resemble an underwater flower swaying in an ocean current. But make no mistake they are marine animals. Picture a flower with mouth on the top surface that is surrounded by feeding arms. Awkwardly, add an anus right beside that mouth. That's him!

Crinoids with root-like anchors are called Sea Lilies. They have graceful stalks that grip the ocean floor. Those in deeper water have longish stalks up to 3.3 ft or a meter in length.

Then there are other varieties with that are free-swimming with only vestigial stalks. They make up the majority of this group and are commonly known as feather stars or comatulids.

Unlike the sea lilies the feather stars can move about on tiny hook like structures called cirri. It is this same cirri that allows crinoids to latch to surfaces on the sea floor.

Like other echinoderms, crinoids have pentaradial symmetry. The aboral surface of the body is studded with plates of calcium carbonate, forming an endoskeleton similar to that in starfish and sea urchins.

These make the calyx somewhat cup-shaped, and there are few, if any, ossicles in the oral (upper) surface called a tegmen. It is divided into five ambulacral areas, including a deep groove from which the tube feet project, and five interambulacral areas between them. The anus, unusually for echinoderms, is found on the same surface as the mouth, at the edge of the tegmen.

Crinoids are alive and well today. They are also some of the oldest fossils on the planet. We have lovely fossil specimens dating back to the Ordovician.

Thursday, 11 April 2019

Tuesday, 9 April 2019


This lovely big fella is Isotelus rex from Churchill, Manitoba, Canada. He was found along the Hudson Bay and is the largest complete trilobite ever found. Isotelus is a genus of asaphid trilobites, an extinct group of arthropods, from the middle and upper Ordovician

Discovered by a paleo dream team, including the deeply awesome, Dave Rudkin, assistant curator of paleobiology at the Royal Ontario Museum, along with Robert Elias (Project Lead), University of Manitoba, Graham Young (Project Lead), associate curator of geology at the Manitoba Museum of Man and Nature (and adjunct professor at the University of Manitoba) and Edward Dobrzanski, Manitoba Museum during a long-term field project in 1998-1999.

The specimen measures in at a whopping 28 inches in length and is 70 percent larger than the previous record holder and warranted a new species name. The image here shows one of several replicas (casts), not the actual holotype specimen which is on exhibit at the Manitoba Museum.

There is a second complete specimen (430 mm in length) of Isotelus rex in the collections of the Geological Survey of Canada (GSC 85292 - a designated paratype). As with many such projects, financial contributions make field work and research possible. A nod to the Natural Sciences and Engineering Research Council of Canada, the University of Manitoba, the Manitoba Museum Foundation nd the Royal Ontario Museum Foundation.

Kudos as well to field crew, David Wright, Curtis Moffat and Janis Klapecki. You arrived four hundred and forty-five million years too late for sunscreen and tropical weather.

In the prophetic words of Eddard Stark, "Winter is Coming." And so it did to the Canadian prairies. Thank you to everyone involved for enduring the frozen cold, wind, rains and hail of northern Manitoba. For those who haven't had the pleasure, dear Manitoba gets blasted by cold Arctic high-pressure that drops it to a frigid -47.2 Celsius. That's a sweet, sweet -52 with wind chill.

Paper: Rudkin, D.A.; Young, G.A.; Elias, R.J.; Dobrzanski, E.P. (2003). "The World's biggest Trilobite: Isotelus rex new species from the Upper Ordovician of northern Manitoba, Canada". Palaeontology. 70 (1): 99–112. doi:10.1666/0022-3360(2003)077<0099:twbtir>2.0.CO;2. ISSN 0022-3360.

Photo credit: Mike Beauregard from Nunavut, Canada. Cast of Isotelus rex. Churchill Manitoba. 2 foot long replica housed at the University of Manitoba. Original specimen is in the Manitoba Museum. The original specimen was recovered the intertidal zone of Hudson Bay.

Sunday, 7 April 2019


Rich McCrae and Heidi Henderson with a Theropod Track

Tuesday, 2 April 2019


Female Spotted Hyena / Sub-Saharan Africa
This lovely lady is a spotted hyena. While she looks like a large dog, she shares more similarities with our large cats, lions and tigers.

Like all her kin, she's a wonderful hunter either with her pack or out solo. While portrayed as scavengers, those who've seen them in the wild know that she's a good little hunter and not a picky eater. Hyenas snack on a varied selection of birds, lizards, snakes, fish and insects over their long lives. Most live about 25 years and are quite social animals. They live in large groups called clans, some up to 75-80 individuals. They eat larger game as well, often hunting with their clan packs to take down zebra, antelope, wildebeest and even young hippos.

Spotted hyenas are mammals in the Family Hyaenidae. They roam the tropical grasslands, woodlands and savanna of Africa. The females are the larger of the species, weighing up to 82 kg and growing up to 2 metres long and are the leaders of the group. Each clan is led by one alpha female who rules the roost and still takes time out to have one ot cubs a year. They are the original working moms.

Monday, 1 April 2019


In Sauropterygia, a diverse group of Mesozoic marine reptiles, fossil evidence of viviparity (live‐bearing) only exists for Pachypleurosauria and Plesiosauria, and was assumed to also be the case for nothosaurs.

Previous studies have successfully applied an extant squamate model to sauropterygian life‐history traits. In extant squamates, oviparity and viviparity are associated with differences in life‐history trait combinations.

A paper released in March 2019, in the journal Palaeontology, sheds light on this view. Griebeler et al. have establish growth curves for Nothosaurus specimens based on their humeral histology.

They analyzed life‐history traits derived from these curves and compared inferred traits to those of modern squamates and pachypleurosaurs to assess their reproduction mode.

Their data shows birth to adult size ratios (i.e. birth size divided by the mother's size) provides a good estimate of clutch sizes in extant squamates and in viviparous extinct marine reptiles, but these ratios cannot discriminate viviparous and oviparous squamates.

Thus, large ratios do not indicate viviparity in fossil taxa to which the extant squamate model is applicable.

Applying differences in birth size, age at maturation, and maximum longevity that are observed between extant viviparous and oviparous squamates to our Nothosaurus sample, they identified 7 out of 24 specimens as being potentially viviparous.

Conversely, they suggested oviparity for many nothosaurs but also for many pachypleurosaur samples.

Under the assumption that the entire clade Pachypleurosauria was viviparous, the majority of nothosaurs would also have been viviparous as they comprised trait combinations similar to those seen in pachypleurosaurs.

Overall, this suggests that within nothosaurs and pachypleurosaurs both reproduction modes existed in different taxa.