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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