An international team of scientists have unearthed the remains of Africa’s oldest dinosaur skeleton. The fossils represent a sauropodomorph, which has been named Mbiresaurus raathi. The fossils were excavated from Pebbly Arkose Formation exposures in Mashonaland Central Province, Zimbabwe. This basal sauropodomorph and the associated vertebrate fauna discovered to date is helping scientists to better understand the dispersal and distribution of early dinosaurs and their contemporaries.

Mbiresaurus raathi

The research team led by palaeontologists from Virginia Tech in collaboration with colleagues from the Natural History Museum of Zimbabwe, the Universidade de São Paulo, (São Paulo, Brazil) and the Chipembele Wildlife Education Centre, (Mfuwe, Zambia) have explored the extensive Upper Triassic sandstone exposures of the Pebbly Arkose Formation. As well as finding the nearly complete and articulated sauropodomorph specimen (M. raathi), the team have been documenting the vertebrate fauna associated with these 230-million-year-old deposits.

The first evidence of Africa’s oldest dinosaur known to science was found during fieldwork in 2017. Two years later, the team returned to excavate more of the specimen and to work on the fossilised remains of an as yet, unnamed theropod dinosaur discovered nearby.

The holotype (NHMZ 2222) consists of a considerable portion of the entire skeleton including skull material. A second specimen (NHMZ 2547), representing a larger individual was discovered in close proximity to the holotype. The research team estimate that Mbiresaurus was around two metres in length and weighed approximately 25 kilograms.

Commenting on the significance of this dinosaur discovery, field team member Christopher Griffin, who graduated in 2020 with a PhD in geosciences from the Virginia Tech College of Science, stated:

“The discovery of Mbiresaurus raathi fills in a critical geographic gap in the fossil record of the oldest dinosaurs and shows the power of hypothesis-driven fieldwork for testing predictions about the ancient past.”

Documenting the Early Dinosauria

South America is regarded by many palaeontologists as the cradle of dinosaur evolution. As far as scientists are able to deduce; based on the fossil record, the dinosaur dynasty began with the evolution of small, agile meat-eaters in South America. However, as landmasses at the time mostly consisted of a single, super-sized continent (Pangaea), it is perfectly feasible to propose that the Dinosauria arose elsewhere and spread across Pangaea.

Dr Griffin added:

“These are Africa’s oldest-known definitive dinosaurs, roughly equivalent in age to the oldest dinosaurs found anywhere in the world. The oldest known dinosaurs, from roughly 230 million years ago, the Carnian Stage of the Late Triassic, are extremely rare and have been recovered from only a few places worldwide, mainly northern Argentina, southern Brazil, and India.”

Sterling Nesbitt, an associate professor at the Department of Geosciences at Virginia Tech and co-author of the scientific paper published this week in the journal “Nature”, explained that basal sauropodomorphs such as Mbiresaurus demonstrate how the early evolutionary history of the Dinosauria is being rewritten with every new discovery.

An Ancient Triassic Biota

The Carnian-aged fossils are providing scientists with evidence of a diverse reptilian biota which co-existed with the earliest dinosaurs. The fieldwork has revealed evidence of cynodonts, aetosaurs (armoured archosaurs more closely related to crocodylians than to the archosaur lineage that led to the birds and the dinosaurs), and rhynchosaurs.

The team also unearthed fossilised remains of an as yet, unnamed theropod dinosaur (herrerasaurid). These archaic animals are similar to the biota associated with contemporaneous deposits found in South America and India.

What’s in a Name?

The genus name Mbiresaurus is from the local Shona language for the name of the district “Mbire” where the fossils were found and from the Greek for lizard. The species name honours palaeontologist Michael Raath for his pioneering work studying vertebrate fossils found in Zimbabwe. The research team conclude that Mbiresaurus was probably bipedal and from an analysis of its small, serrated teeth, it was probably herbivorous although omnivory cannot be ruled out.

A New Theory on the Early Dispersal of the Dinosauria

The researchers have postulated a new theory on dinosaur dispersal. As Africa was once part of the colossal super-continent Pangaea, the distribution and dispersal of the Dinosauria was constrained by climatic conditions across the landmass.

The central portion of Pangaea was dominated by extremely arid environments. These deserts acted as a barrier, the earliest dinosaurs were restricted to southern Pangaea. Only later in their evolutionary history, during a period of climate change resulting in a much wetter climate (Carnian Pluvial Event) did the Dinosauria disperse worldwide.

The research team deliberately targeted Zimbabwe for fieldwork as the northern part of the country would have been located at roughly the same latitude as southern Brazil and India during the Late Triassic.

They conclude that the distribution of the first dinosaurs is correlated with palaeolatitude-linked climatic barriers, and dinosaurian dispersal to the rest of the super-continent was delayed until these barriers were removed. The distribution of the earliest members of the Dinosauria remained restricted by the climatic conditions that prevailed in southern Pangaea.

An Exciting Development for Palaeontology in Zimbabwe

The discovery of a nearly complete specimen of one of the earliest dinosaurs known to science provides a major boost to the Natural History Museum of Zimbabwe and demonstrates that palaeontologists from southern Africa have a major role to play in obtaining evidence about early dinosaur evolution.

Michel Zondo, a curator and fossil preparator at the Natural History Museum of Zimbabwe commented:

“The discovery of the Mbiresaurus is an exciting and special find for Zimbabwe and the entire palaeontological field. The fact that the Mbiresaurus skeleton is almost complete, makes it a perfect reference material for further finds. It is the first sauropodomorph find of its size from Zimbabwe, otherwise most of our sauropodomorph finds from here are usually of medium- to large-sized animals.”

Everything Dinosaur acknowledges the assistance of a media release from Virginia Tech in the compilation of this article.

The scientific paper: “Africa’s oldest dinosaurs reveal early suppression of dinosaur distribution” by Christopher T. Griffin, Brenen M. Wynd, Darlington Munyikwa, Tim J. Broderick, Michel Zondo, Stephen Tolan, Max C. Langer, Sterling J. Nesbitt and Hazel R. Taruvinga published in Nature.

An international team of researchers have uncovered the remains of a huge mosasaur, one that was adapted to hypercarnivory and was an apex predator in the shallow seas of North Africa around 66 million years ago. In addition, the scientists have unearthed remains of other marine vertebrates that shared this giant’s habitat. Acid damage on the bones suggest that these animals were prey and ingested by mosasaurids potentially this new leviathan named Thalassotitan atrox.

Thalassotitan atrox

Late Cretaceous Marine Giant

The remains of this Late Cretaceous marine giant, including a 1.4-metre-long-skull were excavated from the Upper Cretaceous, phosphatic beds of the Ouled Abdoun Basin (northern Morocco). High sea levels created a shallow, tropical sea that teemed with life in North Africa and at the very end of the Cretaceous, approximately 66 million years ago (Maastrichtian faunal stage of the Cretaceous), the 9-metre-long Thalassotitan was the apex marine predator.

A Contemporary of Tyrannosaurus rex

Thalassotitan atrox was a mosasaur, which are extinct members of the largest order of reptiles the Squamata. As such, Thalassotitan was more closely related to snakes and lizards than it was to archosaurs such as crocodilians and the Dinosauria. However, it was a contemporary of Tyrannosaurus rex and like T. rex it was a hypercarnivore, attacking and feeding upon other large vertebrates.

An Apex Predator

The massive jaws and robust, conical teeth suggest that Thalassotitan was an apex predator, filling a similar environmental nice as Orcas (Orcinus orca) and the Great White shark (Carcharodon carcharias) in extant marine ecosystems. The research team, who included Dr Nick Longrich, Senior Lecturer from the Milner Centre for Evolution at the University of Bath and lead author on the study, published in the journal Cretaceous Research, postulate that the acid-etched fossilised bones of other vertebrates found in the same deposit might represent prey ingested by mosasaurids, likely Thalassotitan.

Thalassotitan’s large teeth are often broken and show extensive signs of wear, with some teeth in the jaws worn down to the root. Piscivory (fish-eating) would not have caused this damage, the scientists conclude that this is evidence to support the theory that Thalassotitan was an apex predator.

Dr Longrich commented:

“Thalassotitan was an amazing, terrifying animal. Imagine a Komodo Dragon crossed with a great white shark crossed with a T. rex crossed with a killer whale.”

Thalassotitan’s Potential Victims

The scientists comment that possible remains of Thalassotitan’s victims may have been found. Fossils from the same beds show damage from acid, perhaps evidence of their partial digestion in the stomach of Thalassotitan before the bones and teeth were regurgitated. Fossils with this particular damage include large predatory fish, a sea turtle, a half-metre-long elasmosaurid (plesiosaur) skull, and jaws and skulls of at least three different mosasaur species.

Dr Longrich explained the significance of the acid etched fossil bones and teeth stating:

“It’s circumstantial evidence. We can’t say for certain which species of animal ate all these other mosasaurs. But we have the bones of marine reptiles killed and eaten by a large predator and in the same location, we find Thalassotitan, a species that fits the profile of the killer – it’s a mosasaur specialised to prey on other marine reptiles. That’s probably not a coincidence.”

Mosasaurids Not in Decline Immediately Prior to their Extinction

The discovery of T. atrox along with the other dozen or so mosasaurid genera identified from fossils found in the Ouled Abdoun Basin suggests that mosasaurs continued to diversify and fill new niches until their extinction at the end of the Cretaceous. These marine lizards probably filled ecological niches vacated by the recently extinct ichthyosaurs and they may have out-competed plesiosaurs. The mosasaurs were probably not in decline prior to the end-Cretaceous extinction event.

Co-author of the scientific paper, Professor Nour-Eddine Jalil (Muséum National D’Histoire Naturelle, Paris), added:

“The phosphate fossils of Morocco offer an unparalleled window on the paleobiodiversity at the end of Cretaceous. They tell us how life was rich and diversified just before the end of the ‘dinosaur era’, where animals had to specialise to have a place in their ecosystems. Thalassotitan completes the picture by taking on the role of the megapredator at the top of the food chain.”

A Threat to Other Marine Animals and to Other Thalassotitans

Extensive pathology associated with the fossilised remains of Thalassotitan indicate that these large mosasaurs sustained injuries as a result of combat. Injuries not only sustained through predation but also during intra-specific combat – fights with members of their own species. The skull and jaws show signs of injury. Other mosasaur fossils have similar pathology, but in Thalassotitan these wounds were exceptionally common, suggesting frequent, intense fights over feeding grounds or mates.

Merciless Sea Monster

Although not the largest mosasaurid described to date, specimens from the Tylosaurus and Hainosaurus genera indicate body lengths in excess of twelve metres, Thalassotitan was a formidable predator, and this is emphasised by the binomial scientific name chosen by the research team. The genus name is from the Greek for “sea monster” or “sea titan” and the species name means “cruel or merciless”

Phylogenetic analysis recovers Thalassotitan as a close relative of Prognathodon currii and P. saturator within the Mosasauridae tribe the Prognathodontini. Prognathodon is represented by numerous species all known from the end of the Cretaceous (Campanian to Maastrichtian faunal stages). Prognathodon species are characterised by very robust skulls, with powerful jaws.

More Discoveries Waiting to be Made

Dr Longrich and his colleagues stressed the importance of the prehistoric animal fossils from the Upper Cretaceous of Morocco and hinted that further exciting discoveries are likely to be made.

He stated:

“There’s so much more to be done. Morocco has one of the richest and most diverse marine faunas known from the Cretaceous. We’re just getting started understanding the diversity and the biology of the mosasaurs.”

The extensive, Upper Cretaceous phosphate beds of the Ouled Abdoun Basin have proved palaeontologists with more than a dozen species of mosasaurid to study. Many of these mosasaurs show anatomical adaptations that permitted them to exploit different niches in the ecosystem (niche partitioning). For example, Gavialimimus (G. almaghribensis) had a long, narrow jaw lined with interlocking teeth suggesting that this mosasaur specialised in hunting small fish. In contrast the recently described Pluridens serpentis had disproportionately small eyes, suggesting that this mosasaurid either hunted at depth or within murky water.

To read Everything Dinosaur’s article about P. serpentis: Giant Moroccan Mosasaurid Pluridens serpentis.

Everything Dinosaur acknowledges the assistance of a media release from the University of Bath in the compilation of this article.

The scientific paper: “Thalassotitan atrox, a giant predatory mosasaurid (Squamata) from the Upper Maastrichtian Phosphates of Morocco” by Nicholas R. Longrich, Nour-Eddine Jalil, Fatima Khaldoune, Oussama Khadiri Yazami, Xabier Pereda-Suberbiola, and Nathalie Bardet published in Cretaceous Research.

For models and replicas of mosasaurs and other marine reptiles: CollectA Scale Prehistoric Animal Models.

A new species of chasmosaurine horned dinosaur has been described based on a nearly complete skull found in the vicinity of Alamo Mesa in the Bisti/De-na-zin Federal Wilderness Area (New Mexico). The dinosaur has been named Bisticeratops froeseorum and its discovery lends weight to the hypothesis that there was a thriving dinosaur and vertebrate fauna in north-western New Mexico towards the end of the Cretaceous (Campanian stage).

A New Ceratopsian Dinosaur

Furthermore, the formal scientific description of Bisticeratops froeseorum adds to the growing record of chasmosaurine ceratopsids in the south-western USA and provides new information about the taxonomic diversity of ceratopsids.

Farmington Member (Kirtland Formation)

A nearly complete fossilised skull was discovered in 1975 by a field party from the University of Arizona.

The skull (specimen number NMMNH P-50000) and the holotype for Bisticeratops froeseorum exhibits a combination of character states that clearly differentiate it from the closely related Pentaceratops sternbergi and other chasmosaurines.

The fossil material was recovered from strata associated with the Farmington Member of the upper Kirtland Formation. Dinosaur fossils from the Farmington Member are rare and the biota poorly known. However, the discovery of Bisticeratops results in a substantial increase in the stratigraphic and paleogeographic range of the Chasmosaurinae in the Western Interior Basin of North America.

Bisticeratops froeseorum A New Ceratopsian Species

Based on the skull material and a comparative analysis using more complete fossils from related members of the Chasmosaurinae, the latest member of the diverse ceratopsid biota associated with Laramidia is estimated to have measured around seven metres in length, with brow horns over a metre long.

The Evolutionary Development of the Chasmosaurinae in Southern Laramidia

Writing in the “New Mexico Museum of Natural History and Science Bulletin”, the researchers conclude that in southern Laramidia during the Late Campanian, the Dinosauria were thriving and the biota was experiencing a high faunal turnover with lots of new species evolving.

The formal scientific description of Bisticeratops froeseorum adds to the growing record of chasmosaurine ceratopsids known from the south-western United States and provides new information about the diversity of these horned dinosaurs during the Late Cretaceous.

Two years ago, Everything Dinosaur wrote a blog post about two newly described chasmosaurines from New Mexico (Fowler and Freeman Fowler, 2020). The two newly named horned dinosaurs Terminocavus sealeyi and Navajoceratops sullivani along with other chasmosaurine specimens from the Farmington and De-na-zin Members of the Kirtland Formation (Taxon C), form a sequence of horned dinosaur evolution, stretching over five million years from Utahceratops to Pentaceratops and on to Anchiceratops.

To read Everything Dinosaur’s earlier blog post about T. sealeyi and N. sullivani: Transitional Ceratopsids Knitting Together Horned Dinosaurs.

Roaming Laramidia

Bisticeratops roamed the southern region of the North American landmass known as Laramidia approximately 74 million years ago. If the sandstones and siltstones of the Farmington Member were deposited around 74 million years ago, this suggests that Bisticeratops is approximately 2 million years younger than Pentaceratops sternbergi and Titanoceratops ouranos

Furthermore, Bisticeratops is younger by 1 million years than the recently named Navajoceratops sullivani and 750,000 years younger than Terminocavus sealeyi. Additionally, Bisticeratops is nearly 500,000 years older than the De-na-zin Member (uppermost Kirtland Formation) unnamed chasmosaurines NMMNH P-21100 and NMMNH P-41228. It is also noted that Bisticeratops occurs approximately 1 million years before Sierraceratops turneri.

Bisticeratops froeseorum – What’s in a Name

The genus name references the Bisti/De-na-zin Wilderness Area, the area from which the specimen came; whilst “ceratops” is from the Greek for “horned face”.

The species name “froeseorum” honours the late Edgar Froese the founder and leader of the instrumental music band Tangerine Dream and his son Jerome Froese the former member of Tangerine Dream.
Tangerine Dream is a German instrumental/electronic music band founded in 1967 by Edgar Froese. The group has seen many personnel changes over the years, with Edgar Froese having been the only constant member until his death in 2015. The best-known line-up of the group was in mid 1970s consisting of Edgar Froese, Christopher Franke, and Peter Baumann, then in 1979, Johannes Schmoelling replaced Baumann, and after 5 years Paul Haslinger replaced Schmoelling.

In 1986 the Tangerine Dream trio consisting of Edgar Froese, Christopher Franke, and Paul Haslinger performed in Albuquerque, New Mexico. The concert took place at Kiva Auditorium in downtown Albuquerque.

Senior author of the scientific paper Sebastian Dalman (New Mexico Museum of Natural History) wrote in an email to Everything Dinosaur:

“According to various reports, New Mexico was a favourite place of Tangerine Dream members and every time they toured U.S. they liked to stop by in New Mexico. Today, Tangerine Dream after the passing of Edgar Froese, continues with new members including Thorsten Quaeschning, Hoshiko Yamane, and Paul Frick. I always wanted to honour the band with my scientific work, which their music inspired over the years.”

Our thanks to Tangerine Dream fan Sebastian for his assistance in the compilation of this article.

The scientific paper: “A new chasmosaurine ceratopsid from the Upper Cretaceous (Campanian) Farmington Member of the Kirtland Formation, New Mexico” by Sebastian G. Dalman, Steven E. Jasinski and Spencer G. Lucas published in the New Mexico Museum of Natural History and Science Bulletin.

Researchers from the University of Manchester examining the fossilised remains of a Tenontosaurus have revealed new information about this ornithopod as well as evidence to support a trophic relationship (predator/prey or scavenging) with Deinonychus (D. antirrhopus).

Found in an “Ash Layer” – Cloverly Formation

The fossils of a Tenontosaurus tilletti were discovered on private land in Wheatland County (Montana) in 1994 and acquired by the University of Manchester five years later. The fossils (specimen number MANCH LL.12275) represent one of the most complete and best-preserved T. tilletti known from the fossil record. It was originally described as a mounted, articulated skeleton found with gastroliths and cycad seeds in the stomach region that had been excavated from an ash layer (Cloverly Formation, upper Aptian-lower Albian, upper Lower Cretaceous). In addition, it was stated that two broken Deinonychus teeth had been discovered in association with the cervical vertebrae (neck bones).

The original description of the dinosaur nicknamed “April” was not challenged and the specimen was displayed in the Fossil Gallery of the Manchester Museum, until 2004, when it was replaced with a replica of a Tyrannosaurus rex (“Stan” – BHI 3033).

Not an Ash Layer and No Cycad Seeds

The research team used X-ray CT scanning and X-ray fluorescence (XRF) to assess so-called “seeds” and “ash” found with the specimen and revealed that they were not seeds after all and that the dinosaur did not die in a layer of ash, as had previously been suggested when it was found. The sediment, originally described when the specimen was collected as volcanic ash is actually lime mud. The team concluded that whilst the deposit might consist of a small proportion of volcanic ash, this dinosaur was not buried in a layer of ash as a consequence of a volcanic eruption.

The cycad “seeds” found with the fossilised bones, measure 25 mm and 35 mm in diameter. When analysed, these spherical structures were identified as inorganic mineral concretions and not evidence of the last meal of this plant-eating dinosaur.

Evidence of Gastroliths

When first described for sale, it was stated that twelve gastroliths had been found in the body cavity. Gastroliths are stones found in the digestive tract, they help to grind up plant-material, providing mechanical assistance and aiding the extraction of nutrients from the vegetation consumed. Only a handful of examples of gastroliths being associated with ornithopods have been reported. The research team were able to confirm that the small, smooth pebbles found were most probably gastroliths. These small stones could have been washed into the body cavity of the dead dinosaur, but this idea is not compatible with the muddy sediment (representing a low energy depositional environment), in which the skeleton was entombed.

“April’s” stomach stones are the second oldest occurrence of gastroliths in an ornithopod known to science and the first gastroliths to be identified in a more derived member of the Ornithopoda.

The Diet of Tenontosaurus

Whilst gastroliths have been recorded in a wide variety of extinct vertebrates, only three unambiguous records of gastroliths in ornithopods had been reported previously. The earliest known evidence of stomach stones in a member of the Ornithopoda comes from Changmiania (C. liaoningensis) from the Lower Cretaceous Yixian Formation of Liaoning Province (China), that was formally named and described in 2020 (Yang et al).

To view Everything Dinosaur’s blog post from 2020 about the discovery of Changmiania: The Eternal Sleeping Dinosaur.

The Manchester Tenontosaurus is the largest ornithopod dinosaur known with gastroliths. The confirmation of stomach stones lends weight to the assertion that the teeth and jaws of Tenontosaurus were not as effective at processing vegetation as later, more derived ornithopods such as the Hadrosauroidea. However, the flora and therefore the diet of these herbivores changed dramatically during the Cretaceous as gymnosperms (conifers, cycads and such like) were gradually replaced by angiosperms (flowering plants).

The Deinonychus Teeth

Writing in the academic journal “Cretaceous Research”, the researchers report that one of the broken teeth was now missing but the other tooth most probably comes from a Deinonychus, providing further evidence to support the long-standing assertion, originally made by John Ostrom in 1970, that Tenontosaurus was a common food item for Deinonychus.

Dedicated to Dr Jon Tennant

Doctors Dean Lomax and John Nudds from The University of Manchester dedicated this study to their friend, colleague and co-author, Dr Jon Tennant, who sadly died on 9 April 2020, before this study could be published.

Dr Dean Lomax commented:

“Jon completed his Masters at Manchester on this very specimen, in 2010. It was his idea for the three of us to come together and write this paper, which we officially began in 2018. Jon contributed significantly to palaeontology and was a massive advocate for open access. At every opportunity Jon encouraged others and was immensely passionate about palaeontology. This project would not have been possible if it was not for his research on the specimen described herein. Jon leaves a remarkable legacy behind.”

Whilst predator/prey relationships are often inferred, this specimen provides further evidence to support the hypothesis that Deinonychus fed on Tenontosaurus. The completeness and exceptional state of preservation suggests that further study of “April” may yield yet more information about the life and behaviour of this Early Cretaceous dinosaur.

Everything Dinosaur acknowledges the assistance of a press release from the University of Manchester in the compilation of this article.

The scientific paper: “Gastroliths and Deinonychus teeth associated with a skeleton of Tenontosaurus from the Cloverly Formation (Lower Cretaceous), Montana, USA” by John R. Nudds, Dean R. Lomax and Jonathan P. Tennant published in Cretaceous Research.

Researchers have announced the discovery of a new species of Late Cretaceous armoured dinosaur from fragmentary fossils found in North Patagonia, (Río Negro Province, Argentina). It may represent an entirely new and previously unknown branch of the armoured dinosaur family tree from South America (Gondwana). Named Jakapil kaniukura (pronounced Jack-a-pil can-nee-ook-your-rah), it is the first definitive thyreophoran species from the Patagonia of Argentina and it might have been a biped with short, stumpy arms reminiscent of the abelisaurid theropod dinosaurs.

Fossils from the “La Buitrera Paleontological Area” (LBPA)

Writing in the academic journal “Scientific Reports”, researchers from the Universidad Maimónides (Buenos Aires, Argentina) in collaboration with a colleague from the Universidad del País Vasco/Euskal Herriko Unibertsitatea (Bilbao, Spain), report the discovery of a fragmentary, disarticulated skeleton representing a sub-adult animal, from the upper beds of the Candeleros Formation (early Late Cretaceous 94-97 million years ago). The sandstone exposures represent aeolian (wind borne) sand dunes indicating an arid to semi-arid palaeoenvironment in what is now termed the “La Buitrera Paleontological Area” (LBPA). The holotype (MPCA-PV-371), consists of skull elements including bones from the jaw, rib fragments, bones from the shoulders, two partial upper arm bones (humeri), a possible partial right ulna and other assorted fragmentary limb bones. Fifteen partial teeth were also recovered along with numerous osteoderms (dermal armour).

The sub-adult animal is estimated to have had a body length of less than 1.5 metres, perhaps weighing around 4.5 to 7 kilograms.

Commenting on the significance of this fossil discovery, lead author of the paper Facundo Riguetti (Universidad Maimónides), stated:

“Our finding is important for several reasons. On the one hand, Jakapil expands the fossil record known in the region and allows us to know a little better the prehistoric ecosystem of our land, and specifically of the ancient Kokorkom desert, today northern Patagonia.”

The PhD student went onto add:

“Moreover, this new species represents a lineage of thyreophoran dinosaurs previously unknown in South America. The Thyreophora originated about two hundred million years ago and evolved rapidly into several species distributed throughout the world. However, of these early thyreophorans, the lineage represented by Jakapil was the only one that persisted until at least a hundred million years ago.”

A Survivor from an Ancient Armoured Dinosaur Line

Phylogenetic analysis recovers Jakapil kaniukura either as a basal member of the Thyreophora or a stem ankylosaur, closely related to Scelidosaurus, fossils of which are associated with the Lower Jurassic Charmouth Mudstone Formation of Dorset, England. Its discovery suggests that early thyreophorans had a much broader geographic distribution than previously thought and that an ancient lineage persisted into the early Late Cretaceous.

A Bipedal Armoured Dinosaur

Evolutionary trends observed in armoured dinosaurs suggest a transition between small, cursorial, light-weight species to much larger, heavily armoured quadrupedal forms epitomised by the likes of Stegosaurus in the Late Jurassic and Ankylosaurus and Edmontonia in the Late Cretaceous. The relative dimensions of the forelimb and hind limb bear a greater resemblance to those of bipedal theropods and basal ornithischian dinosaurs than they do to members of the Thyreophora.

The reduced nature of the upper arm, indicated by the fragmentary humeri resembles the arm bones of abelisaurids – famous for their tiny, almost vestigial front limbs.

Etymology

The genus name is from the northern Tehuelchean language meaning “shield bearer”, whilst the species name is derived from the Mapudungun language for “crest” (kaniu) and “stone” (kura) which references the diagnostic bony crest on the lower jaw.

The researchers, including co-author Sebastián Apesteguía (Universidad Maimónides) speculate that Jakapil, if it was a biped, resembled Scutellosaurus, which is known from the Early Jurassic of Arizona. However, they caution against defining this little armoured dinosaur as bipedal. They observe that it still retains some anatomical characteristics associated with a quadrupedal stance and they comment that more complete limb bones are required to make a more accurate assessment of its locomotion.

Everything Dinosaur acknowledges the assistance of a media release from the Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) in the compilation of this article.

The scientific paper: “A new Cretaceous thyreophoran from Patagonia supports a South American lineage of armoured dinosaurs” by Facundo J. Riguetti, Sebastián Apesteguía and Xabier Pereda-Suberbiola published in Scientific Reports.

Plesiosaur fossils found in strata associated with a 100-million-year-old river system prove that some plesiosaurs, traditionally thought to be marine animals, may have lived in freshwater. These long-necked, piscivores co-existed with the giant dinosaur Spinosaurus (S. aegyptiacus).

Freshwater Plesiosaurs

Scientists from the University of Bath and University of Portsmouth in the UK, and Université Hassan II (Morocco), have reported evidence small plesiosaurs from Kem Kem Group deposits in Morocco.

The fossils include bones and teeth from three-metre-long adults and an arm bone (humerus) from a 1.5- metre-long juvenile. They hint that these creatures routinely lived and fed in freshwater, alongside frogs, crocodiles, turtles, fish, and the huge aquatic dinosaur Spinosaurus.

When is a “Marine Reptile” a Marine Reptile?

The Plesiosauria clade was a long-lived and widely distributed group of marine reptiles. Most fossils, which date from the Upper Triassic to the end of the Cretaceous (Maastrichtian faunal stage), are associated with marine deposits, but a few specimens have been found in strata associated with brackish and freshwater environments. The researchers report plesiosaurs from river deposits of the Kem Kem Group. The numerous shed teeth show heavy wear similar to that observed in in the teeth of coeval spinosaurids. Contemporary plesiosaur fossils from the Bahariya Formation of Egypt have been identified as examples of the Polycotylidae plesiosaur family.

Kem Kem Fossils

The Kem Kem fossils probably represent leptocleidid plesiosaurs. Most Leptocleididae fossils come from shallow nearshore, brackish or freshwater palaeoenvironments suggesting that these small-bodied plesiosaurs were adapted to shallow, low-salinity environments.

As the fossil plesiosaur teeth show the same signs of wear as the teeth of Spinosaurus, the researchers imply that the plesiosaurs were eating the same food – chipping their teeth on the armoured fish that lived in the river. This indicates that they spent a lot of time in the river, rather than being occasional visitors.

As other types of Mesozoic marine reptile (mosasaurids and the crocodile-like teleosaurids), are thought to have inhabited (at least some of the time), freshwater environments, this suggests that so-called “marine reptiles” may have thrived in non-marine habitats.

Co-author of the scientific paper, Dr Nick Longrich (University of Bath Milner Centre for Evolution), commented:

“It’s scrappy stuff, but isolated bones actually tell us a lot about ancient ecosystems and animals in them. They’re so much more common than skeletons, they give you more information to work with. The bones and teeth were found scattered and in different localities, not as a skeleton. So, each bone and each tooth is a different animal. We have over a dozen animals in this collection.”

Diverse and Varied Kem Kem Group Freshwater Fauna

While extant marine mammals like whales and dolphins wander up rivers, either to feed or because they are lost, the number of plesiosaur fossils in the river deposits suggest that is unlikely. The team identified cervical, dorsal and caudal vertebrae, lots of teeth and the humerus from a juvenile. The researchers postulate that the plesiosaurs were able to tolerate fresh and salt water, like some whales, such as the beluga whale (Delphinapterus leucas).

Co-author Dr Samir Zouhri said:

“This is another sensational discovery that adds to the many discoveries we have made in the Kem Kem over the past fifteen years of work in this region of Morocco. Kem Kem was truly an incredible biodiversity hotspot in the Cretaceous.”

Plesiosaurs – Freshwater Incursions

The researchers compiled a list of all the geological formations that have shown evidence for the presence of members of the Plesiosauria clade in brackish or freshwater. Having collated this information, they re-examined the data identifying the different types of plesiosaur associated with the deposit.

As a result, a map documenting the incidences of freshwater incursions by different plesiosaur types was produced.

For the key to the geological formations see the end of this article.

Co-author David Martill (University of Portsmouth) exclaimed:

“What amazes me is that the ancient Moroccan river contained so many carnivores all living alongside each other. This was no place to go for a swim.”

Plesiosaurus Swam Alongside Spinosaurus

Key to the Geological Formations Featured in the Plesiosaur Map

Geographic distribution of non-marine Plesiosauria Formations: 1, Dinosaur Park Formation (Campanian); (2), Horseshoe Canyon Formation (Campanian – Maastrichtian); 3, Isachsen Fm. (Late Aptian); 4, Strand Fiord Formation (Turonian – Coniacian); 5, Great Estuarine Group (Bathonian); 6, La Colonia Formation (Upper Campanian – Lower Maastrichtian); 7, Wadhurst Clay Formation (Valanginian); 8, Tunbridge Wells Sands Formation (Upper Valanginian); 9, Wessex Formation (Barremian); 10, Upper Weald Clay Formation (Barremian); 11, Vectis Formation (Barremian – Aptian); 12, Obernkirchen Sandstone (Late Berriasian);
13, Bükerberg Formation (Berriasian); 14, Kem Kem beds (Cenomanian – Albian?); 15, Chenini Formation (Albian); 16, Bahariya Formation (Cenomanian), 17, Sunday River Formation (Valanginian); 18, Lianmugin Formation (Upper Aptian); 19, Xinhe Formation (Middle Jurassic); 20, Ziliujing Formation (Toarcian); 21, Xintiangou Formation (Middle Jurassic), 22, Xiashaximiao Formation (Middle Jurassic); 23, Shezi Formation (Upper Triassic); 24, Razorback Beds (Sinemurian); 25, Evergreen Formation (Pliensbachian – Toarcian); 26, Griman Creek Formation (Albian); 27, Eumeralla Formation (Aptian) 28; Wonthaggi Formation (Valanginian – Aptian), 29 Eumeralla Formation (Upper Aptian – Lower Albian). Note that some formations contain more than one occurrence.

Everything Dinosaur acknowledges the assistance of a media release from the University of Bath in the compilation of this article.

The scientific paper: “Plesiosaurs from the fluvial Kem Kem Group (mid-Cretaceous) of eastern Morocco and a review of non-marine plesiosaurs” by Georgina Bunker, David M. Martill, Roy Smith, Samir Zouhri and Nick Longrich.

For models and replicas of plesiosaurs and Spinosaurus figures: CollectA Deluxe Prehistoric Life Scale Replicas.