November
17, 2018, Harvard
University
These
days, mammals can use their forelimbs to swim, jump, fly, climb, dig and just
about everything in between, but the question of how all that diversity evolved
has remained a vexing one for scientists.
To help
answer it, Harvard researchers are
turning to one of the most unusual mammals around—echidnas. These sprawling,
egg-laying mammals have many anatomical features in
common with earlier mammal ancestors,
and so can help bridge the gap between extinct and other modern-day mammals.
Using a
highly-detailed musculoskeletal model of an echidna forelimb, Sophie
Regnault, a Post-Doctoral Fellow and Stephanie Pierce, Associate Professor of
Organismic and Evolutionary Biology, were able to not only shed more light on
how the little-studied echidna's forelimb works, but also open a window into
understanding how extinct mammals might have used their forelimbs. The model is described
in a November 14 paper published in Royal Society Open Science.
"Echidnas
are not very well-studied, and little is known about their biomechanics."
Regnault says. "There are few related species, and echidnas
themselves can be difficult to study because they have very large spines hiding
underlying movements. We made this virtual model using CT scans that allow us
to look in closer detail at how the skeleton and muscles interact with one
another."
The
researchers discovered that the bony anatomy and muscles work together to
optimize limb leverage and mobility for certain kinds of movements. In
particular, the configuration of muscles support limb rotation important for
the echidna's sprawling gait.
"This
model gives us unique insight into not only the echidna but can also guide
reconstructions of extinct mammals," Pierce says. "The similarities
between the echidna forelimb skeleton and transitional animals can help us to
understand the evolution of forelimb diversity in modern mammals."
Posts
