Page 50 - 2007 DT 12 Issues

Really, Really Big! Lake Vostok. How this behemoth came many species generated some internal
to be at all is an amazing example of heat because they did not have to return
n the badlands of east-central opportunity and adaptation. to land to keep their body temperature up
Nevada, in what is now the Berlin- The greatest mass extinction event and their biochemistry active. According
IIchthyosaur State Park, lie the in earth’s history occurred about 250 to Ryosuke Motani, a vertebrate paleon-
remains of a group of Shonisaurus million years ago and ended the Perm- tologist at the Royal Ontario Museum in
popularis, a 225 million year old species ian Era. Approximately 90 to 95% Toronto, their large body mass would
of ichthyosaur unknown until 1953 of all species on earth disappeared. have helped them maintain a tempera-
when the site was excavated and the Throughout earth’s history, extinction ture higher than the surrounding water,
fossils described by Charles Camp of events have provided an opportunity for like modern leatherback turtles.
the University of California. Most of the the survivors to spread out and fill the All of these sea-dwelling giants
animals still lie buried where they died vacancies, giving rise to entirely new were air breathers. Some species, like
but of the, at least, 37 specimens found, classes and species of animal life. Early Stenopterygius, developed with an ef-
reptiles quickly took advantage ficient streamlined tunniform shape
of this unprecedented catastrophe and an essentially unbendable spine,
Doug Henderson and about 30 million years later, enabling it to cruise fast and deep at

the first dinosaurs were roaming speeds similar to today’s marlin and yel-
the land.
lowfin tuna without pausing frequently
Some lizard-like reptiles, to surface for air. Belemites, a species
however, chose to exploit the of deep-dwelling squid, were their
riches of the thinly populated favored prey. Other species had the
ocean ecosystems and abandoned flexible spine and lizard-like proportions
the land altogether almost im- of their landlubber ancestors, undulating
mediately. They evolved into eel-like when they swam, making them
ichthyosaurs—Greek for
Beached Ichthyosaurs
fish lizards—and prolifer-
several have been removed and are now ated into at least 80 known
housed in a sheltered display for public ichthyosaur species—some eely
viewing. One resides in the Nevada State sleek, others still substantially lizard-
Museum in Las Vegas. How so many of like—taking on the role that dolphins,
these marine predators died at the same seals and whales (all mammals) oc-
place and time remains a mystery. cupy today. For 150 million years,
The Park, 100 miles southeast of almost as long as the dinosaurs ruled
Fallon, occupies what was once part the land, these sea dragons were the
of the continental margin, still covered undisputed rulers of the seas, disap-
by shallow seas 200 million years ago. pearing from the fossil record in the Belemites—U. Mich. Museum Exhibit
One of the specimens extracted from mid-Cretaceous 90 million years ago,
the rocks was 50-plus feet in length and a full 25 million years before mass die-offs slower and far less efficient, having to
weighed in at over 40 tons. Until recent- finally finished the dinosaurs. surface often to inhale enough oxygen
ly, it was the largest known ichthyosaur Ichthyosaurs were diapsids, but to sustain a high speed while chasing
fossil in the world. It is still the largest only very distantly related to croco- prey. They may have, however, adopted
ever found in the United States and has diles, birds, lizards and snakes. Unlike a leaping style known as “porpoising,”
been Nevada’s state fossil since 1977. fish, these once-four legged (tetrapod) grabbing a breath on the fly.
The ichthyosaur was prolific in the animals retained their hand, finger and To accommodate deep diving,
seas of the Triassic and Jurassic epochs. foot bones within their flippers or fin- many species evolved enormous eyes
Different species have been discovered shaped limbs. They also gave live birth to hunt in low-light conditions. Fos-
and described all over the world, from in the sea, much like warm blooded sea sil evidence also suggests that some
the Himalayas to the Antarctic ice of mammals do today. It is probable that ichthyosaurs might have had supple-

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