How dinosaur research can help medicine
Even Tyrannosaurus rex could have suffered a slipped disc

Date:
August 24, 2020
Source:
University of Bonn
Summary:
The intervertebral discs connect the vertebrae and give the spine
its mobility. The disc consists of a cartilaginous fibrous ring
and a gelatinous core as a buffer. It has always been assumed
that only humans and other mammals have discs. A misconception,
as a research team has now discovered: Even Tyrannosaurus rex
could have suffered a slipped disc.



FULL STORY ==========================================================================
The intervertebral discs connect the vertebrae and give the spine its
mobility.

The disc consists of a cartilaginous fibrous ring and a gelatinous core as
a buffer. It has always been assumed that only humans and other mammals
have discs. A misconception, as a research team under the leadership of
the University of Bonn has now discovered: Even Tyrannosaurus rex could
have suffered a slipped disc. The results have now been published in
the journal "Scientific Reports."

========================================================================== Present-day snakes and other reptiles do not have intervertebral discs; instead, their vertebrae are connected with so-called ball-and-socket
joints.

Here, the ball-shaped end surface of a vertebra fits into a
cup-shaped depression of the adjacent vertebra, similar to a human hip
joint. In-between there is cartilage and synovial fluid to keep the joint mobile. This evolutionary construction is good for today's reptiles,
because it prevents the dreaded slipped disc, which is caused by parts
of the disc slipping out into the spinal canal.

"I found it hard to believe that ancient reptiles did not have
intervertebral discs," says paleontologist Dr. Tanja Wintrich from the
Section Paleontology in the Institute of Geosciences of the University of
Bonn. She noticed that the vertebrae of most dinosaurs and ancient marine reptiles look very similar to those of humans -- that is, they do not have ball-and-socket joints. She therefore wondered whether extinct reptiles
had intervertebral discs, but had "replaced" these with ball-and-socket
joints in the course of evolution.

Comparison of the vertebrae of dinosaurs with animals still alive today
To this end, the team of researchers led by Tanja Wintrich and with
the participation of the University of Cologne and the TU Bergakademie
Freiberg as well as researchers from Canada and Russia examined a total
of 19 different dinosaurs, other extinct reptiles, and animals still
alive today. The researchers concluded that intervertebral discs not
only occur in mammals. For these investigations, vertebrae still in
connection were analyzed using various methods.

Surprisingly, Dr. Wintrich has now also been able to demonstrate that
remnants of cartilage and even other parts of the intervertebral disc
are almost always preserved in such ancient specimens, including marine reptiles like ichthyosaurs and dinosaurs like Tyrannosaurus. She then
traced the evolution of the soft tissues between the vertebrae along the
family tree of land animals, which 310 million years ago split into the mammalian line and the dinosaur and bird line.

Intervertebral discs emerged several times during evolution It was
previously unknown that intervertebral discs are a very ancient feature.

The findings also show that intervertebral discs evolved several times
during evolution in different animals, and were probably replaced
by ball-and-socket joints twice in reptiles. "The reason why the
intervertebral disc was replaced might be that it is more susceptible to
damage than a ball-and-socket joint," says Dr. Wintrich. Nonetheless,
mammals have always retained intervertebral discs, repeating the
familiar pattern that they are rather limited in their evolutionary flexibility. "This insight is also central to the medical understanding
of humans. The human body is not perfect, and its diseases reflect our
long evolutionary history," adds paleontologist Prof. Dr. Martin Sander
from the University of Bonn.

In terms of research methods, the team drew not only on paleontology,
but also on medical anatomy, developmental biology and zoology. Under
the microscope, dinosaur bones cut with a rock saw and then ground
very thinly provide information comparable to histological sections of
fixed and embedded tissue of extant animals. This makes it possible
to bridge the long periods of evolution and identify developmental
processes. Prof. Sander remarks: "It's truly amazing that the cartilage
of the joint and apparently even the disc itself can survive for hundreds
of millions of years." Dr. Wintrich, who now works at the Institute
of Anatomy of the University of Bonn, is pleased about the cooperation
between the fields that has made this interdisciplinary understanding
possible in the first place: "We found that even Tyrannosaurus rex was
not protected against slipped discs." Only bird-like predatory dinosaurs
then evolved ball-and-socket joints as well and saddle joints, still seen
in today's birds. Likewise, such ball-and-socket joints were a decisive advantage for the stability of the spine of the largest dinosaurs,
the long-necked dinosaurs.

This bridge between paleontology and medicine is seminal in Germany. The anatomist Prof. Dr. Karl Schilling from the University of Bonn, who
was not involved in the new study, reports: "In the USA, in contrast,
dinosaur researchers and evolutionary biologists are often closely
involved in medical training, especially in anatomy and embryology. This
gives young doctors a perspective that is becoming increasingly important
in a rapidly changing environment."

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


========================================================================== Journal Reference:
1. Tanja Wintrich, Martin Scaal, Christine Bo"hmer, Rico Schellhorn,
Ilja
Kogan, Aaron van der Reest, P. Martin Sander. Palaeontological
evidence reveals convergent evolution of intervertebral joint
types in amniotes.

Scientific Reports, 2020; 10 (1) DOI: 10.1038/s41598-020-70751-2 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/08/200824105616.htm

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