Analysis of sediments taken from the famous Prince Creek Formation of northern Alaska has revealed tiny, fossilised bones and teeth representing perinatal dinosaurs – either embryonic (just about to hatch) or dinosaurs that have recently hatched. Several different types of dinosaurs are represented, which means that high latitudes in the Northern Hemisphere were probably the dinosaur’s permanent home and that they nested there.

A Dinosaur Nursery

Researchers from the University of Alaska Museum, the Royal Tyrrell Museum, Florida State University and the University of Colorado writing in the academic journal “Current Biology”, report the discovery of tiny teeth — some less than 2 mm in length along with bones from seven species of perinatal dinosaurs. These tiny fossils were found after conducting a microscopic analysis of sediments from the bluffs that can be found along the shores of the Coleville River. These sediments are from the Prince Creek Formation and represent deposition that took place around 70 million years ago,

The field season is very short at such a high latitude. In the three weeks of field work that are possible, the team removed hundreds of kilograms of sediment from the face of the bluffs. The buckets of sediment are hauled down to the river’s edge, where team members wash the material through smaller and smaller screens until they have removed any large rocks and soil.

Once back at the lab, researchers run the material through more screens to remove all the clay, until all that’s left is sandy particles. Then, teaspoon by teaspoon, the team, including graduate and undergraduate students examine the sand under microscopes to find the tiny bones and teeth. This work has revealed tiny teeth of mammals, but in addition, tiny teeth and bones of dinosaurs have been discovered.

Endothermic Dinosaurs

Although not as cold as today, conditions in this part of northern Laramidia during the Late Cretaceous were extremely challenging. For around 120 days each year there was total darkness and it has been calculated that the mean average temperature was just 6.3°C ± 2.2°C (43.3°F ± 4.0°F). The Eumeralla and Wonthaggi Formations of Australia at a palaeolatitude of about 70° south, have also provided evidence of recently hatched dinosaurs and yearlings.

However, the Prince Creek Formation at a latitude of 80°– 85° north represents the most extreme environment yet described for the Dinosauria. Intriguingly, whilst dinosaurs living in southern Gondwana (Eumeralla and Wonthaggi Formation fossil remains), would have experienced around 45 days of total darkness each year, this palaeoenvironment was still warm enough for ectothermic animals such as crocodilians and amphibians to thrive. However, no such “cold-blooded” animals are found in association with Prince Creek Formation sediments.

To survive such harsh conditions, the researchers conclude that the dinosaurs of Prince Creek Formation were endothermic, just like modern mammals and birds.

Lead author of the research Patrick Druckenmiller (University of Alaska Museum) commented:

“Recovering these tiny fossils is like panning for gold. It requires a great amount of time and effort to sort through tonnes of sediment grain-by-grain under a microscope. The fossils we found are rare but are scientifically rich in information”.

Dinosaurs were Year-round Residents of Northern Alaska

The presence of such young dinosaurs, who were not capable of making long, seasonal migrations is strong evidence to suggest that the dinosaur biota was present all year. The palaeoenvironment was extreme but numerous different types of dinosaur were able to thrive in this harsh habitat.

This discovery demonstrates just how adaptable members of the Dinosauria were and hints at a diverse and rich dinosaur dominated ecosystem hundreds of miles inside the Palaeo-Arctic Circle.

The scientific paper: “Nesting at extreme polar latitudes by non-avian dinosaurs” by Patrick S. Druckenmiller, Gregory M. Erickson, Donald Brinkman, Caleb M. Brown and Jaelyn J. Eberle published in Current Biology.

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A new species of ancient beetle has been named and described based on preserved remains found in the poo (coprolite) of an ancestor of the dinosaurs. The beetle named Triamyxa coprolithica, is the first insect to be scientifically described from coprolite and this research, suggests that coprolite remains could become as important as insects preserved in amber when it comes to identifying new species.

Published in Current Biology

The researchers from Uppsala University (Sweden), in collaboration with entomologists from Sun Yat-sen National University (Taiwan), Jena University (Germany) and Guadalajara University in Mexico used synchrotron microtomography to examine the coprolite’s contents and sophisticated computer software to rebuild the tiny insects so that they could be studied. The coprolite contained numerous insect remains preserved in three-dimensions. Most insect fossils are squashed so flat that deciphering them is extremely difficult.

The researchers conclude that coprolites may prove to be an important source of information for exploring insect evolution. Their paper is published this week in “Current Biology”.

Silesaurus opolensis

Although the scientists cannot be certain, they speculate that the coprolite represents the scat from a relative of the dinosaurs called Silesaurus opolensis, which is known from the same Polish deposits associated with the coprolite. An animal (probably S. opolensis), swallowed a large number of these tiny insects 230 million years ago, the greedy reptile inadvertently giving palaeontologists a rare opportunity to study a beetle, at a time (the Triassic), when many different types of insect were evolving and diversifying.

Phylogenetic analysis suggests that T. coprolithica is a member of Myxophaga (fungal beetles), a small suborder of beetles with a sparse fossil record whose extant representatives are small and often associated with wet environments.

Complete Specimens Preserved

Some of the beetles were almost complete with even their antennae and thin legs intact and attached to the body.

Commenting on the significance of this research, lead author of the scientific paper, Martin Qvarnström, (Uppsala University), remarked:

“We were very positively surprised by how many beetle remains there were in the coprolite and above all how well preserved they were. We really have to thank Silesaurus, who was probably the animal that helped us collect and preserve the beetles”.

The labrador-sized Silesaurus did not usually dine on such small insects, it probably was a generalist eating a wide variety of prey. It had a beak that was possibly used to bite insects just like today’s living dinosaurs – the birds. Despite the fact that Silesaurus ingested lots of individuals of Triamyxa coprolithica, these small beetles probably did not constitute its main food. Triamyxa lived in the same environments as larger insects and it was these insects as well as small vertebrates that probably made up the majority of the diet of this fast running, agile reptile.

The beetle fossils are reminiscent of other beetle remains associated with amber. Both coprolites and amber are capable of preserving insects in three-dimensions and this study suggests coprolites can be extremely valuable for studying early insect evolution and extinct animal food chains at the same time.

The scientific paper: “Exceptionally preserved beetles in a Triassic coprolite of putative dinosauriform origin” by
Martin Qvarnström, Martin Fikáček, Joel Vikberg Wernström, Emmanuel Arriaga-Varela, Per E. Ahlberg and Grzegorz Niedźwiedzki published in Current Biology.

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The giant prehistoric rhino, Paraceratherium, is considered the largest land mammal that ever lived. It was mainly found in Asia, especially China, Kazakhstan, Mongolia and Pakistan. How these giant, hornless rhinos dispersed across Asia was unknown, but the discovery of fossils in Gansu Province, has led to the naming of a new Paraceratherium species (Paraceratherium linxiaense) and shed light on how these amazing herbivores evolved and dispersed across the Asian continent.

Providing Important Clues About Paraceratherium Dispersal

Writing in the academic journal “Communications Biology”, the researchers from the Chinese Academy of Sciences, the Hezheng Paleozoological Museum (Gansu Province), Henan University (Henan Province) and Harvard University describe fossils found near the village of Wangjiachuan (Gansu Province) in 2015 that enabled the establishment of a new species of Paraceratherium.

Analysis of the fossil material led the scientists to conclude that this new species was closely related to giant rhinos that once lived in Pakistan (Paraceratherium bugtiense), which suggests ancestral forms migrated across Central Asia.

The Remarkable Fauna of the Linxia Basin in the Late Oligocene

The fossil material which includes a skull and articulated mandible as well as the first cervical vertebra (atlas), as well as another neckbone and two thoracic vertebrae from a second individual were found in Late Oligocene deposits associated with the Jiaozigou Formation of Linxia Basin (Gansu Province), close to the north-eastern border of the Tibetan Plateau.

Around 26.5 million years ago, the open woodland environment of north-central China was home to a wide variety of prehistoric mammals including the giant rhinos Turpanotherium and Dzungariotherium, the rodent Tsaganomys, the creodont Megalopterodon, the chalicothere Schizotherium, the hyracodont Ardynia, the rhinocerotid Aprotodon, and the entelodont Paraentelodon – some of these animals are illustrated in the Paraceratherium linxiaense life reconstruction (above).

Standing taller than a giraffe and weighing approximately 20 tonnes, Paraceratherium linxiaense had a slender skull and a prehensile nose trunk similar to that of the modern tapir to help it to grab leaves and branches from the tops of trees, a food resource that no other animal in its environment could exploit.

Plotting the Distribution and Dispersal of Paraceratherium

A phylogenetic analysis carried out by the research team suggests P. linxiaense as a derived form with a mix of basal and more advanced traits. The phylogenetic analysis produced a series of progressively more-derived species from P. grangeri, through P. huangheense, P. asiaticum, and P. bugtiense before finally terminating in P. linxiaense and what is thought to be its sister taxon P. lepidum.

The research team conclude that Paraceratherium linxiaense was a more specialised animal, with a more flexible neck, similar to P. lepidum, and both are derived from Paraceratherium bugtiense known from Pakistan. They team were then able to plot and map the spread of these giant rhinos across Asia.

The researchers found that all six species of Paraceratherium are sister taxa to the hornless rhinoceros Aralotherium which is known from Kazakhstan and China and form a monophyletic clade in which P. grangeri is the most primitive, succeeded by P. huangheense and P. asiaticum.

The researchers were thus able to determine that, in the Early Oligocene, P. asiaticum dispersed westward to Kazakhstan and its descendant lineage expanded to South Asia as Paraceratherium bugtiense. In the Late Oligocene, Paraceratherium returned northward, crossing the Tibetan region, which implies that this area of Asia was not yet uplifted to form a high, difficult to traverse plateau. This migration led to two distinct species evolving P. lepidum to the west in Kazakhstan and P. linxiaense to the east in the Linxia Basin.

Picture credit: Everything Dinosaur

Contrasting the high altitude of the Tibetan region today to the environment of this region during the Late Oligocene Epoch, lead author of the research Professor Deng Tao explained that:

“Late Oligocene tropical conditions allowed the giant rhino to return northward to Central Asia, implying that the Tibetan region was still not uplifted as a high-elevation plateau.”

During the Oligocene, the giant rhino could disperse freely from the Mongolian Plateau to South Asia along the eastern coast of the Tethys Ocean and perhaps through Tibet. Up to the Late Oligocene, the evolution and migration from P. bugtiense to P. linxiaense and P. lepidum demonstrates that the “Tibetan Plateau” was not yet a barrier to the movement of the largest land mammal known to science.

The scientific paper: “An Oligocene giant rhino provides insights into Paraceratherium evolution” by Tao Deng, Xiaokang Lu, Shiqi Wang, Lawrence J. Flynn, Danhui Sun, Wen He and Shanqin Chen published in Communications Biology.

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Earlier this spring, a team of researchers led by Pavel Skutschas (St Petersburg University, Russia), published a paper reporting on the study of 63 stegosaur teeth that had been found in Lower Cretaceous deposits in south-western Yakutia, located in eastern Siberia. Just like today, during the Early Cretaceous this part of Siberia was at a high latitude (palaeolatitude estimate of N 62°- 66.5°) and within the Arctic circle. The scientists conclude that these stegosaurs may have had some special adaptations to help them survive their harsh environment, such as a rapid tooth replacement rate to permit them to cope with a diet mainly consisting of conifer needles and branches.

Stegosaurs Probably Present All Year

There has been much debate amongst palaeontologists as to whether large herbivorous dinosaurs such as stegosaurs were permanent residents of high latitude palaeoenvironments, or whether they migrated up to these latitudes in the summer to take advantage of the long periods of daylight. In the height of summer, there would have been around twenty-two hours of daylight at this latitude presumably providing very favourable conditions for plant growth.

The researchers, writing in the on-line, academic journal PLOS One report the discovery of smaller stegosaur teeth in the excavations, which took place in 2012 and then in the summer months from 2017-2019. As it is thought that the teeth represent a single species of stegosaur, this indicates that both adults and juveniles were present at this site.

Lead author Pavel Skutschas an Associate Professor in the Department of Vertebrate Zoology at St Petersburg University commented:

“We have found teeth of animals of different ages. This suggests that the polar stegosaurs are most likely to have been sedentary that they reproduced and raised offspring on the same territory all year round”.

A Diverse Prehistoric Fauna

The researchers from St Petersburg University worked together with colleagues from the Zoological Institute of the Russian Academy of Sciences, the Borissiak Paleontological Institute of the Russian Academy of Sciences, the University of Bonn (Germany) and the Diamond and Precious Metal Geology Institute of the Siberian Branch of the Russian Academy of Sciences to examine, excavate and sieve material from the Batylykh Formation, Sangar Series (Lower Cretaceous, Berriasian–Barremian faunal stage) along the banks of the Teete River in Suntar Ulus, Yakutia, Eastern Siberia.

This location has yielded dinosaur fossils (including theropods as well as ornithischian dinosaurs), turtles, salamanders and early mammals.

Stegosaurian remains are the most abundant and consist of numerous isolated teeth, vertebrae, ribs, pelvic elements and occasional cranial material. The stegosaur teeth were all retrieved by screen washing and sieving samples. Most exhibit a high degree of wear and indicate that these animals fed on very abrasive plant material. In addition, study of the tiny scratches on the teeth suggest tooth on tooth contact and precise dental occlusion in the Teete River stegosaurs.

Studying Stegosaurs

The microwear examined suggests that these animals had a more complex jaw movement to help them process food in their mouths, the tooth wear observed could not have occurred if these dinosaurs were only capable of moving their jaws up and down in a simple scissor-like action.

Rapid Tooth Replacement

Under the microscope, the researchers made another surprising discovery. The Teete stegosaurs are characterised by their relatively short tooth formation time. The teeth were rapidly replaced and the replacement teeth were formed in a relatively short time (95 days). This might have been an adaptation to the particularly abrasive diet of these herbivores which probably fed on conifers. Furthermore, the scientists identified the presence of a “wavy enamel pattern” on the teeth.

This type of enamel has also been found on the teeth of Psittacosaurus, a basal member of the horned dinosaurs (Ceratopsia) and within the Ornithopoda. The researchers conclude that this feature of teeth is a shared trait amongst bird-hipped dinosaurs. Whether it was present in the ancestor of the ornithischian dinosaurs or whether this histological feature is an example of convergent evolution in different types of plant-eating dinosaur is not known.

The scientific paper: “Wear patterns and dental functioning in an Early Cretaceous stegosaur from Yakutia, Eastern Russia” by Pavel P. Skutschas, Vera A. Gvozdkova, Alexander O. Averianov, Alexey V. Lopatin, Thomas Martin, Rico Schellhorn, Petr N. Kolosov, Valentina D. Markova, Veniamin V. Kolchanov, Dmitry V. Grigoriev, Ivan T. Kuzmin and Dmitry D. Vitenko published in PLOS One.

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