Fossil jawbone from Alaska is a rare case of a juvenile Arctic
dromaeosaurid dinosaur
This fossil is a clue to the history of how dinosaurs dispersed between continents, showing some dinosaurs likely nested in the far north

Date:
July 8, 2020
Source:
PLOS
Summary:
A small piece of fossil jawbone from Alaska represents a rare
example of juvenile dromaeosaurid dinosaur remains from the Arctic,
according to a new study.



FULL STORY ==========================================================================
A small piece of fossil jawbone from Alaska represents a rare example
of juvenile dromaeosaurid dinosaur remains from the Arctic, according
to a study published July 8, 2020 in the open-access journal PLOS ONE
by Alfio Alessandro Chiarenza of the Imperial College London, UK, and co-authors Anthony R.

Fiorillo, Ronald S. Tykoski, Paul J. McCarthy, Peter P. Flaig, and Dori L.

Contreras.


========================================================================== Dromaeosaurids are a group of predatory dinosaurs closely related to
birds, whose members include well-known species such as Deinonychus
and Velociraptor.

These dinosaurs lived all over the world, but their bones are often
small and delicate and rarely preserve well in the fossil record,
complicating efforts to understand the paths they took as they dispersed between continents.

The Prince Creek Formation of northern Alaska preserves the largest
collection of polar dinosaur fossils in the world, dating to about 70
million years ago, but the only dromaeosaurid remains found so far have
been isolated teeth. The jaw fossil described in this study is a mere
14mm long and preserves only the tip of the lower jaw, but it is the
first known non-dental dromaeosaurid fossil from the Arctic. Statistical analysis indicates this bone belongs to a close relative of the North
American Saurornitholestes.

North American dromaeosaurids are thought to trace their origins to
Asia, and Alaska would have been a key region for the dispersal of their ancestors. This new fossil is a tantalizing clue toward understanding
what kinds of dromaeosaurs inhabited this crucial region. Furthermore,
the early developmental stage of the bone suggests this individual
was still young and was likely born nearby; in contrast to previous
suggestions that this part of Alaska was exclusively a migratory pathway
for many dinosaurs, this is strong evidence that some dinosaurs were
nesting here. The authors suggest that future findings may allow a more complete understanding of these mysterious Arctic dromaeosaurids.

Chiarenza summarizes: "There are places where dinosaur fossils are so
common that a scrap of bone, in most cases, cannot really add anything scientifically informative anymore: this is not the case with this Alaskan specimen. Even with such an incomplete jaw fragment, our team was not only
able to work out the evolutionary relationships of this dinosaur, but also
to picture something more on the biology of these animals, ultimately
gaining more information on this Ancient Arctic ecosystem." Fiorillo
adds: "Years ago when dinosaurs were first found in the far north,
the idea challenged what we think we know about dinosaurs. For some
time afterwards, there was a great debate as to whether or not those
Arctic dinosaurs migrated or lived in the north year round. All of
those arguments were somewhat speculative in nature. This study of a
predatory dinosaur jaw from a baby provides the first physical proof
that at least some dinosaurs not only lived in the far north, but they
thrived there. One might even say, our study shows that the ancient north
was a great place to raise a family and now we have to figure out why."

========================================================================== Story Source: Materials provided by PLOS. Note: Content may be edited
for style and length.


========================================================================== Journal Reference:
1. Alfio Alessandro Chiarenza, Anthony R. Fiorillo, Ronald S. Tykoski,
Paul
J. McCarthy, Peter P. Flaig, Dori L. Contreras. The first juvenile
dromaeosaurid (Dinosauria: Theropoda) from Arctic Alaska. PLOS ONE,
2020; 15 (7): e0235078 DOI: 10.1371/journal.pone.0235078 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/07/200708150611.htm

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