WASHINGTON, DC.- The Smithsonians National Museum of Natural Historys fossilized skeleton of the Jurassic dinosaur Allosaurus has officially been named the type specimen for the entire species. This distinction makes the specimen, which is displayed in the museums David H. Koch Hall of Fossils Deep Time, the single physical example researchers will refer to when they describe new fossils of Allosaurus fragilis, one of the most iconic species of dinosaurs in the world.
The specimens new status was bestowed by members of the International Commission on Zoological Nomenclature (ICZN). According to paleontologist Matthew Carrano, the museums curator of dinosauria, the change was more than a decade in the making and represents a coveted scientific honor.
In 2010, a petition was made to the ICZN to solve the problem that the very famous and scientifically important dinosaur A. fragilis was based on materials that couldnt really be identified as anything more than a non-descript predatory dinosaur, Carrano said. This decision really emphasizes how important our specimen isboth historically and in the presentfor dinosaur science.
Stretching over 20 feet and sporting a mouthful of dagger-like teeth, Allosaurus terrorized other dinosaurs during the Late Jurassic Period some 150 million years ago. The prehistoric predator lived in western North America alongside other well-known species like the armored Stegosaurus and a number of supersized sauropod dinosaurs like Diplodocus.
The Dawn of American Paleontology
The name Allosaurus has been in the scientific lexicon for nearly 150 years. But it did not always belong to a well-known dinosaur. In 1877, Yale University paleontologist Othniel Charles Marsh was in the midst of a contentious scientific competition now known as the Bone Wars with rival Edward Drinker Cope to discover and name new species of dinosaurs from the western United States. To keep pace with Cope, Marsh described a set of fragmentary fossils from the Jurassic-aged Morrison Formation in Colorado as a new species of predatory dinosaur. Because the animals vertebrae varied from other dinosaurs known at the time, Marsh came up with the name Allosaurus, which means different lizard in Greek. He rounded out the creatures scientific identity with the species name fragilis due to its delicate remains.
Marsh deposited this relatively meager specimenwhich included a tooth, toe bone and a couple of vertebrae from the backbonein the collection of the Peabody Museum of Natural History at Yale University (now the Yale Peabody Museum). Because Marsh used these fossils to formally describe A. fragilis, this sample became the species official type specimen.
Many prehistoric species enter the scientific record on the basis of scant remains. Complete specimens of dinosaurs are incredibly rare, so scientists are often forced to use fragmentary fossils. Even if paleontologists eventually find more complete specimens, the fossils that were initially described usually retain their type status on a scientific first-come, first-served basis.
But Allosaurus represents an intriguing case for a taxonomic do-over. Shortly after Marsh described the fragmentary type specimen, paleontologists unearthed more substantial Allosaurus fossils that provided a much fuller picture of the Jurassic carnivore. In 1884, one of Marshs collectors uncovered a nearly complete Allosaurus skeleton in a Colorado quarry. The specimen was shipped back to Marsh, but he was not able to conduct a detailed description of the fossil before he died in 1899.
Allosaurus Arrives at the Capital
After his death, a large portion of Marshs fossils were transferred to the Smithsonians United States National Museum (the precursor to the National Museum of Natural History). Museum paleontologist Charles Gilmore led the effort to unpack, prepare and catalog Marshs fossils and integrate them into the museums burgeoning National Fossil Collection. This trove of fossils included the nearly complete Allosaurus specimen from Colorado.
In 1920, Gilmore described this specimen, cataloged as USNM V 4734, in depth for the first time. The resulting paper cleared up the confusion that had surrounded the species for decadesCope and Marsh had both mistakenly described other Allosaurus specimens as different, now-defunct dinosaur species. Gilmores work helped drive these erroneous scientific names into extinction and made the museums specimen an essential piece of the Allosaurus puzzle.
Gilmores paper has remained an important reference for paleontologists and really established our specimen as a sort of flagship individual for Allosaurus, said Carrano, who is currently working on updating Gilmores century-old description of USNM V 4734. As a result, our specimen has functioned as a sort of de facto type.
Museum visitors are able to see the historic Allosaurus specimen displayed in the museums Deep Time fossil hall along with the type specimen of its fossil foe, Stegosaurus, and the sauropods Diplodocus and Camarasaurus. The exhibitions Allosaurus mount, which contains the animals real fossilized bones, displays the dinosaur in a rarely seen position. Instead of chasing down prey, the Allosaurus skeleton is crouched down like a modern bird as it guards a clutch of fossilized eggs.
USNM V 4734 has always been a prize of the Smithsonians dinosaur collection, Carrano said. Now it has a prominent position in the Deep Time hall, reflecting aspects of its biology that were unimagined in Marsh or Gilmores times.
This summer, the museum is celebrating the fifth year anniversary of the David H. Koch Hall of FossilsDeep Time. The world-class hall, which contains some 700 mounted fossil specimens including the Allosaurus type, explores the epic story of how Earths distant past is connected to the present and informs the future. As the anniversary approaches, the museum is also putting a remarkable, rainbow-hued ammonite fossil on display in the museums Objects of Wonder exhibition. The shimmering shell dates back 70 million years to the Late Cretaceous Period and is considered an organic gemstone thanks to its iridescent colors.