Muscular study provides new information about how the largest dinosaurs
moved and evolved

Date:
January 19, 2022
Source:
University of Bristol
Summary:
New research has revealed how giant 50-ton sauropod dinosaurs,
like Diplodocus, evolved from much smaller ancestors, like the
wolf-sized Thecodontosaurus.



FULL STORY ==========================================================================
New research led by the University of Bristol has revealed how giant
50-tonne sauropod dinosaurs, like Diplodocus, evolved from much smaller ancestors, like the wolf-sized Thecodontosaurus.


==========================================================================
In a new study published today in the journal Royal Society Open
Science, researchers present a reconstruction of the limb muscles of Thecodontosaurus, detailing the anatomy of the most important muscles
involved in movement.

Thecodontosaurus was a small to medium sized two-legged dinosaur that
roamed around what today is the United Kingdom during the Triassic period (around 205 million years ago).

This dinosaur was one of the first ever to be discovered and named
by scientists, in 1836, but it still surprises scientists with new
information about how the earliest dinosaurs lived and evolved.

Antonio Ballell, PhD student in Bristol's School of Earth Sciences
and lead author of the study, said: "The University of Bristol houses
a huge collection of beautifully preserved Thecodontosaurus fossils
that were discovered around Bristol. The amazing thing about these
fossilised bones is that many preserve the scars and rugosities that the
limb musculature left on them with its attachment." These features are extremely valuable in scientific terms to infer the shape and direction of
the limb muscles. Reconstructing muscles in extinct species requires this
kind of exceptional preservation of fossils, but also a good understanding
of the muscle anatomy of living, closely related species.



========================================================================== Antonio Ballell added: "In the case of dinosaurs, we have to look at
modern crocodilians and birds, that form a group that we call archosaurs, meaning 'ruling reptiles'. Dinosaurs are extinct members of this lineage,
and due to evolutionary resemblance, we can compare the muscle anatomy
in crocodiles and birds and study the scars that they leave on bones to identify and reconstruct the position of those muscles in dinosaurs."
Professor Emily Rayfield, co-author of the study, said: "These kinds
of muscular reconstructions are fundamental to understand functional
aspects of the life of extinct organisms. We can use this information
to simulate how these animals walked and ran with computational tools."
From the size and orientation of its limb muscles, the authors argue
that Thecodontosauruswas quite agile and probably used its forelimbs to
grasp objects instead of walking.

This contrasts with its later relatives, the giant sauropods, which
partly achieved these huge body sizes by shifting to a quadrupedal
posture. The muscular anatomy of Thecodontosaurus seems to indicate
that key features of later sauropod-line dinosaurs had already evolved
in this early species.

Professor Mike Benton, another co-author, said: "From an evolutionary perspective, our study adds more pieces to the puzzle of how the
locomotion and posture changed during the evolution of dinosaurs and in
the line to the giant sauropods.

"How were limb muscles modified in the evolution of multi-ton quadrupeds
from tiny bipeds? Reconstructing the limb muscles of Thecodontosaurus
gives us new information of the early stages of that important
evolutionary transition." This research was funded by the Natural
Environment Research Council (NERC).

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


========================================================================== Journal Reference:
1. Antonio Ballell, Emily J. Rayfield, Michael J. Benton. Walking
with early
dinosaurs: appendicular myology of the Late Triassic sauropodomorph
Thecodontosaurus antiquus. Royal Society Open Science, 2022; 9
(1) DOI: 10.1098/rsos.211356 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/01/220119121332.htm

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