CREATURES HAVE BEEN ON EARTH FOR MILLIONS OF YEARS
February 1, 2009
article by Farish A. Jenkins Jr. of Harvard University and colleagues
was published in the Journal of Vertebrate Paleontology, a scientific
journal that reports research findings based on fossil material. This
particular article would be of interest to paleontologists and evolutionary
biologists because of the comparisons of skeletal features among fossil
vertebrates in general and amphibians in particular. It was of interest
to me because it discussed an ancient extinct amphibian that opened its
mouth in an unusual manner. Although the creature was bizarre and deserves
odd-creature recognition, we should remind ourselves that we have equally
strange and remarkable creatures alive on earth with us today.
The fossil amphibian, known by the genus name Gerrothorax, lived about
200 million years ago in the Late Triassic and reached a length of about
three feet. It had a wide head and big jaws; its signature trait was that
it opened its mouth by lifting the upper jaw rather than dropping the
lower jaw like most animals. Presumably the monster sat on the bottom
of an aquatic habitat, possibly buried in the sand with only its eyes
visible. When a small animal such as a fish or baby turtle swam by, Gerrothorax
would lift its jaw rapidly and suck the unwitting prey in as a meal. Cool
stuff, to be sure, but before we marvel too much about the capabilities
of predators of the past, consider what we still have here with us today.
example of mouth movement and feeding mechanisms is that of the matamata,
a South American turtle. The matamata has a black and brown shell and
body, and crinkly skin on the neck--ideal camouflage as the turtle sits
motionless in dark and muddy water. And why would it want to go unseen?
Because live fish and other aquatic animals are its prey, which it captures
by opening its mouth, quickly expanding its throat, and sucking in the
unsuspecting animal. After the powerful suction brings a fish into the
matamata's mouth, the predator expels excess water and debris, and then
swallows the animal whole.
example of an unusual use of mouthparts is the alligator snapping turtle
of southern rivers and swamps. These so-called sit-and-wait predators
patiently remain in one spot and let their food find them. Fish literally
swim into the turtle's mouth as it lies still on the bottom, mouth wide
open. The reason fish make such a foolish mistake is because the turtle's
tongue is a worm-like appendage that functions as a lure when the turtle
wiggles it. The fish sees what looks like a free meal and swims right
beneath the hooked beak and into the powerful jaws that snap shut.
people, the most impressive feature of the fossil amphibian Gerrothorax
would not be its peculiar manner of opening its mouth but instead its
large size, approaching that of a basset hound. Typical amphibians of
today are tree frogs, stream salamanders, and garden toads, none of which
reach more than a few inches in length or weigh more than a pound. Nonetheless
a few big amphibians are still with us. A full-grown bullfrog is an impressive
sight, but the world's biggest frog, the goliath frog of West Africa,
could eat one if given the opportunity. A goliath frog with its legs outstretched
is about two feet long. They can weigh around eight pounds.
Some modern salamanders are also large. The secretive amphiuma of southeastern
wetlands can reach lengths over three feet. Hellbenders of clear, rocky
streams are slightly shorter but because of their more robust body shape
can weigh up to five pounds. The largest salamanders in the world are
in Japan and China. They are related to hellbenders, some reaching lengths
of more than five feet.
that lived on earth millions of years ago have a certain fascination for
most of us, and we are intrigued with what paleontologists can tell us
about the behavior of these long-extinct creatures. But an eight-pound
frog, a five-foot salamander, and a snapping turtle with a worm-like tongue
are intriguing in their own right. And those are only three of the many
natural wonders still with us today.
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