Researchers have discovered the earliest evidence known to science of birds nesting in the Arctic.  A newly published study in the journal “Science” indicates that birds were nesting in polar regions during the Late Cretaceous.  Ancient Arctic birds nested alongside dinosaurs.  Fossils collected from the famous Prince Creek Formation of Alaska push back the record of Arctic nesting birds by up to thirty million years.

An illustration of Cretaceous Period birds with other dinosaurs from the same time period in the background. A paper in the journal Science documents the earliest-known example of birds nesting in the polar regions. A dromaeosaur feeds whilst Pachyrhinosaurus congregate in the background. Picture credit: Gabriel Ugueto.

Picture credit: Gabriel Ugueto

Ancient Arctic Birds

The University of Alaska Fairbanks led the research team.  However, researchers from the University of Reading were involved.  The scientists identified dozens of tiny fossil bones and teeth from the Alaskan excavation site.  Multiple types of birds were breeding in the Arctic. For example, diving birds that resembled loons, gull-like birds, and several kinds of birds similar to modern ducks and geese.  Analysis of the structure of the fossil material demonstrated that the bones represented very young birds such as hatchlings.

A hatchling bird beak, top left, and three foot bones are pictured to scale on a penny. The bones’ spongy texture tells scientists that they come from hatchlings, rather than adult birds. Picture credit: Pat Druckenmiller.

Picture credit: Pat Druckenmiller

The sediments are approximately seventy-three million years old (late Campanian faunal stage of the Cretaceous).

To read a blog post about dinosaurs nesting in the Arctic: Dinosaurs Nested in the Arctic.

Lead author of the study, Lauren Wilson, a doctoral student at Princeton University commented:

“Birds have existed for 150 million years. For half of the time they have existed, they have been nesting in the Arctic. Finding bird bones from the Cretaceous is already very rare. To find baby bird bones is almost unheard of. That is why these fossils are significant.”

More than Fifty Bird Fossils Found

Birds are key components in modern polar ecosystems.  Many species breed in these regions and spend all year either in the Arctic or Antarctic.  Although the Cretaceous polar regions were much warmer than today, they were still extreme, harsh environments.  Cretaceous polar regions would have experienced months of near total darkness.  They were challenging environments to colonise even though they were not as cold as they are today.  The fossil assemblage from the Prince Creek Formation suggests that chicks and adults of multiple species lived in the Arctic.  This suggests that birds began breeding in the Arctic early on in their evolution.

Prior to this research, the earliest known evidence of birds breeding in the polar regions dates to approximately forty-seven million years ago.  This was during the Eocene Epoch. The fossil material used in this study was collected from Prince Creek Formation exposures along the Colville River. Rather than focusing on large bones, the scientists collected every bone and tooth they could find from screen washes. Screen washing involves taking tubs of sediment and screening the sediments using sieves.  Once the majority of the stones and pebbles have been removed the remaining material is examined under a microscope.  In this way, tiny fossils including those of hatchling birds can be identified.

Joe Keeney, Patrick Druckenmiller and Jim Baichtal excavate at a site on the Colville River. Picture credit: Lauren Wilson.

Picture credit: Lauren Wilson

Evidence of Neornithes

Some of the tiny bones have skeletal features only found in Neornithes, the group that includes all extant birds. Like extant birds, some of these ancient species had no true teeth.

Co-author of the study, Dr Jacob Gardner (University of Reading) commented:

“Determining the identity of fossils using separate individual bones is notoriously difficult. For the first time, we determined the identities of large numbers of fossils using high-resolution scans and the latest computer tools, revealing an enormous diversity of birds in this ancient Arctic ecosystem. Polar bird communities have deeper evolutionary roots than previously imagined.”

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

The scientific paper: “Arctic bird nesting traces back to the Cretaceous” by Wilson, L. N., Ksepka, D. T., Wilson, J. P., Gardner, J. D., Erickson, G. M., Brinkman, D., Brown, C. M., Eberle, J. J., Organ, C. L. and Druckenmiller, P. S. published in the journal Science.

For models and replicas of prehistoric animals: Dinosaur and Prehistoric Animal Models.

Newly published research suggests that Allosaurus europaeus is not a valid taxon. A detailed study of Portuguese fossil material has led to the conclusion that the A. europaeus holotype (ML 415) represents Allosaurus fragilis.

The remains of large theropods ascribed to the Allosaurus genus have been found in Portugal. In 1988, fossils of a meat-eating dinosaur were discovered near the village of Andrés, (Leiria District, Portugal). Additional fossil finds from the coast at Praia de Vale Frades, (Lourinhã, Portugal) and a coal mine in the district of Leiria were assigned to Allosaurus. Subsequently, a European Allosaurus was erected in 2006 (Mateus et al). This dinosaur was named Allosaurus europaeus.  However, a detailed analysis of cranial material has led researchers to conclude that fossils attributed to A. europaeus should be bracketed as Allosaurus fragilis.

A life-size replica of an Allosaurus. The genus was first erected in 1877 (Marsh). Several species have been named but the validity of many of these species has been challenged. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The Demise of Allosaurus europaeus

Allosaurus fragilis was first described in the Upper Jurassic of Portugal in 1999 based on a set of postcranial remains collected at the Andrés fossil site in Pombal. The description of a second species, Allosaurus europaeus, based on elements from the back of the skull and a sequence of tail bones (ML 415) collected at Praia de Vale Frades in Lourinhã was controversial.  The scientists provide a detailed description of a new sample of skull fossil material.  These fossils from the village of Andrés are confidentially assigned to the Allosaurus genus.

In addition to the fossil study a comprehensive phylogenetic assessment of the Morrison Formation fossil record of Allosaurus was performed. The phylogenetic analysis indicates that there were only two valid Allosaurus species present in the Late Jurassic ecosystems of North America.  These species are Allosaurus fragilis and the recently erected Allosaurus jimmadseni.

To read Everything Dinosaur’s blog post about the establishment of A. jimmadseni as a separate species: A New Species of Allosaurus.

Manufacturers of prehistoric animal models were quick to introduce replicas of this new Allosaurus species.  Allosaurus jimmadseni was erected in 2020.  The American company Creative Beast Studios introduced an articulated replica of A. jimmadseni.

This figure has proved popular with collectors, especially collectors based in the USA.

To view the range of Beasts of the Mesozoic/Cenozoic figures: Beasts of the Mesozoic Figures.

The new Beasts of the Mesozoic Cyberzoic figure (A. jimmadseni) is one of the highlights of the latest customer newsletter. Shortly, after this new species was erected, new Allosaurus models came onto the market. Picture credit: Everything Dinosaur.

Referring Specimens to Allosaurus fragilis

The authors of the paper postulate that their analysis indicates that only two valid Allosaurus species were present in the Late Jurassic ecosystems of North America.  These two species are Allosaurus fragilis and Allosaurus jimmadseni.  The researchers provide an updated reference for Allosaurus classification.  The Portuguese specimens MNHN/UL.AND.#, ML 415, and MG 27804 are interpreted as belonging to A. fragilis.

This new research helps palaeontologists to better understand the evolution of theropods associated with the Lusitanian Basin.  The researchers consider that this study provides evidence of a close biogeographical relationship between North America and Europe during the Late Jurassic.

The scientific paper: “Cranial osteology of a new specimen of Allosaurus Marsh, 1877 (Theropoda: Allosauridae) from the Upper Jurassic of Portugal and a specimen-level phylogenetic analysis of Allosaurus” by Elisabete Malafaia, Pedro Dantas, Fernando Escaso, Pedro Mocho and Francisco Ortega published in the Zoological Journal of the Linnean Society.

The Everything Dinosaur website: Dinosaur Models.

Researchers have identified fossil tracks with skin impressions of early synapsids from the famous Bromacker fossil site in Thuringia (Germany).  These are the oldest skin impressions of early mammalian relatives known.  They provide unique insights into the evolution of scales and integumentary coverings within an Early Permian ecosystem.  The Bromacker quarry exposes 290-million-year-old deposits associated with the Tambach Formation. This rare site preserves exquisite, articulated fossils of a unique vertebrate fauna.  This quarry has been at the centre of a long research project, lasting decades led by the Museum für Naturkunde Berlin.

290-million-year-old skin impression fossils. Picture credit: Lorenzo Marchetti.

Picture credit: Lorenzo Marchetti

Studying the Trace Fossils of Early Synapsids

The fossil tracks were discovered over a century ago. These rare fossils were re-examined as part of the ongoing Bromacker research project.  This research project is run by the Federal Ministry of Research, Technology and Space.  The scientific paper has been published in the journal “Current Biology”.

Senior author of the study, Professor Jörg Fröbisch commented:

“It has been shown time and again that certain characteristics and traits of modern vertebrates, such as skin structure, lifestyle or social behaviour, appeared earlier in the course of evolutionary history than was initially assumed. The study once again demonstrates the globally unique significance of the fossil deposit at Bromacker and its enormous potential for future research.”

To read a blog post about a Dimetrodon fossil found at the Bromacker locality: Fossil Mystery is Solved.

Scales on the Underside, Legs and the Tail

One trackway preserved at the site is particularly illuminating. An impression preserved in the fine-grained Tambach sandstone reveals skin folds on the toes and various types of scales on the upper and lower legs.  There are also scale impressions from the ventral portion of the tail, the hip area and the abdomen.  The scientists have identified this as a resting track or evidence of a Permian vertebrate wallowing.

The arrangement and shape of the scale marks, sometimes diamond-shaped, rectangular, pentagonal to polygonal, sometimes overlapping like roof tiles, is reminiscent of the horny scales of membranous reptiles.

Evidence of Social Behaviour in Early Synapsids

A number of sandstone slabs preserve large numbers of tracks.  Several tracks are adjacent to each other, and some tracks are parallel.  The researchers suggest this is evidence of animals of the same species walking together.  The track producers, early synapsids such as Dimetrodon teutonis, probably rested, basked and cooled down together.  This suggests that these Permian animals demonstrated group behaviours, just like modern lizards, birds and mammals.

Everything Dinosaur acknowledges the assistance of a media release from the Museum für Naturkunde Berlin in the compilation of this article.

The scientific paper: “Early Permian synapsid impressions illuminate the origin of epidermal scales and aggregation behaviour” by Marchetti, L., Logghe, A., Buchwitz, M., and Fröbisch, J. published in Current Biology.

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