Spinosaurus fossils
Spinosaurus
THE biggest, and possibly the baddest predatory dinosaur of them all was not
the fabled Tyrannosaurus rex, or even its slightly larger rival Giganotosaurus,
but a long-jawed, sail-backed creature called Spinosaurus.
An examination of some newly obtained dinosaur fossils shows that Spinosaurus stretched
an impressive 17 metres from nose to tail, dwarfing its meat-eating relatives.
Excavated dinosaur bones indicate that longer than its rivals, Spinosaurus also
had stronger arms with which to catch its prey, unlike the puny-armed T.
rex and its ilk.
Until 10 years ago, T. rex held the mantle of the biggest predatory
dinosaur skeleton discovered. Of the 30 dinosaur skeletons collected so far,
the largest and most complete is a fossil called Sue, kept at the Field Museum
of Natural History in Chicago. She measures 12.8 metres long and is thought to
have weighed 6.4 tonnes when alive.
Enter Giganotosaurus, a meat-eating dinosaur that lived in what is now
Argentina. Reconstruction of a partial dinosaur skeleton indicated that it stretched
13.7 metres. It lived around the same time as two other huge predatory theropod
dinosaurs were stalking other continents. The slightly smaller Carcharodontosaurus lived
in Africa while Acanthosaurus lived in North America, the only one of
the three dinosaur skeletons for which we have more than a handful of fragmentary
dinosaur fossils. All three predators were closely related to Allosaurus,
a 9 to 12-metre-long predator of a lighter build than T. rex which was
common in North America.
However, Spinosaurus has been casting its fearsome shadow over all these
beasts for some time. German palaeontologist Ernst Stromer discovered the first
and best dinosaur skeleton specimen in 1912 in Egypt. He identified it as a long-snouted
giant predator which he believed was bigger than T. rex, and published
a detailed study of the dinosaur bones, including a partial backbone with long
spines on the vertebrae, which may have supported a sail. Stromer's fossils were
obliterated when allied bombers hit a Munich museum in 1944. Since then, all
that has been discovered are some specimens of related smaller spinosaurs, as
well as some isolated dinosaur bones of Spinosaurus itself.
But a new examination of two skull fragments of Spinosaurus has confirmed
its early reputation. Analysis of a snout acquired from an Italian collector,
and previously unidentified dinosaur bones from the upper rear of the dinosaur
skull collected by the University of Chicago, both of which were originally unearthed
in Morocco.
With long slender snouts, interlocking dinosaur teeth, spinosaurs were like theropods
with crocodile mouths.
After measuring their sizes, it was estimated that the 99-centimetre-long snout
came from a skull 1.75 metres long. From what we know of the body shapes of other
spinosaur dinosaurs, it was calculated that the new Spinosaurus was
17 metres long and weighed 7 to 9 tonnes.
Spinosaurus lived alongside Carcharodontosaurus in Africa,
and like T. rex and Giganotosaurus was a theropod dinosaur.
Spinosaurs, with their very long and slender snouts are more like theropods with
crocodile mouths. Their long dinosaur teeth interlocked to catch prey, and a
sawfish vertebra stuck between a tooth socket and an emerging tooth in one dinosaur
fossil specimen supports the idea that Spinosaurus preyed largely on
fish. Other specimens also suggest that spinosaurs had arms strong enough to
be used in catching prey.
T. rex and Giganotosaurus were doing very different things. T.
rex had puny arms, but its stout skull had massive banana-shaped teeth that
could crunch through bone, where Giganotosaurus had a much more slender
skull, with blade-like dinosaur teeth to slice through flesh.
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