Just Our Type: Museum’s Dinosaur Skeleton Becomes the Scientific Standard for Its Species

In this month’s Specimen Spotlight, find out what makes the Smithsonian’s Allosaurus specimen so special

The museum’s fossil specimen of Allosaurus fragilis is perched like a nesting bird guarding a clutch of fossilized eggs. USNM V 4734, Department of Paleobiology, Smithsonian Institution. Photo by Mike Gaudaur

With more than 148 million specimens and objects in its collection, the vast majority of the National Museum of Natural History’s specimens are off display. But everything — whether it be a moth, meteorite, moss or mammoth — tells a story that helps museum researchers make sense of the natural world. Each month, the Specimen Spotlight series will highlight a different specimen or object from the world’s largest natural history collection to shed light on why we collect.

In 1883, fossil collector Marshall P. Felch unearthed a nearly complete dinosaur skeleton in central Colorado. The dinosaur, which had a mouthful of dagger-like teeth, dated back to the Late Jurassic period some 150 million years ago.

Felch sent his find to Yale University’s preeminent paleontologist, Othniel Charles Marsh. At that time, Marsh was engaged in a contentious competition with fellow paleontologist Edward Drinker Cope to name the most new species of dinosaur from the western United States. To keep pace in what is now known as the ‘Bone Wars’, Marsh described a set of fragmentary fossils from Colorado as a new species of dinosaur named Allosaurus fragilis in 1877.

The skeleton that Felch sent to Marsh in 1883 offered a much more complete picture of Allosaurus. But Marsh was not able to closely study the skeleton before he died in 1899. The specimen was then shipped to the Smithsonian, where paleontologist Charles Gilmore unpacked and described it. As Gilmore studied this remarkable specimen in depth, he realized that the animal Marsh described as Allosaurus was among the most fearsome predators of the Jurassic.

This Allosaurus specimen, which is now on display in the National Museum of Natural History’s Deep Time Hall of Fossils, was recently recognized for its scientific importance. The fossil is now the official type specimen for the entire Allosaurus species. This makes it the primary physical example researchers will refer to when they describe new Allosaurus fossils.
The skeleton of the Allosaurus fragilis type specimen in the museum’s Deep Time Hall of Fossils. Lucia R.M. Martino, Smithsonian Institution

The specimen’s new status was bestowed by members of the International Commission on Zoological Nomenclature (ICZN). According to paleontologist Matthew Carrano, the museum’s 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 Allosaurus fragilis was based on materials that couldn’t really be identified as anything more than a nondescript predatory dinosaur,” Carrano said. “This decision really emphasizes how important our specimen is — both historically and in the present — for dinosaur science.”

Dawn of American Paleontology

While the specimen took a decade to achieve its new type status, the story of Allosaurus dates back to the early epochs of American paleontology. As Marsh feuded with his rival Cope, he was keen to describe and name any dinosaur remains he came across. Even fragmented fossils were fair game.

A portrait of paleontologist Othniel Charles Marsh taken around 1875, two years before he named the species Allosaurus from a set of fragmentary fossils. Smithsonian Institution Archives

This led him to describe a relatively meager assemblage of fossils — a tooth, toe bone and a couple of vertebrae — as a new species in 1877. Because the animal’s 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 creature’s scientific identity with the species name fragilis due to its delicate remains.

These initial Allosaurus fossils were deposited in the collection of Marsh’s institution, 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’ original type specimen.

Many prehistoric species enter the scientific record on the basis of scant remains because complete specimens of dinosaurs are incredibly rare. Even if paleontologists eventually unearth more complete specimens, the fossils that were initially described usually retain their type status on a scientific first-come, first-served basis.

The skull of the Allosaurus fragilis type specimen in a photo dating from around 1980. USNM V 4734, Department of Paleobiology, Smithsonian Institution.

But Allosaurus represents an intriguing case for a taxonomic do-over. Shortly after Marsh described the fragmentary type specimen, fossil hunters like Felch unearthed more substantial Allosaurus fossils that provided much more information on the Jurassic carnivore.

Allosaurus Arrives in the Capital

The skeleton that Felch collected was among the many fossils that were transferred after Marsh’s death to the Smithsonian’s 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 Marsh’s fossils and integrate them into the museum’s burgeoning National Fossil Collection.

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 decades — Cope and Marsh had both mistakenly described other Allosaurus specimens as different, now-defunct dinosaur species. Gilmore’s work helped drive these erroneous scientific names into extinction and made the museum’s specimen an essential piece of the Allosaurus puzzle.
Charles Gilmore, who served as the museum’s curator of vertebrate paleontology, examines vertebrae from the Jurassic sauropod Diplodocus around the year 1930. Smithsonian Institution Archives

“Gilmore’s 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 Gilmore’s century-old description of USNM V 4734. “As a result, our specimen has functioned as a sort of de facto type.”

Thanks to its new taxonomic designation, the Smithsonian’s Allosaurus skeleton joins the roughly 139,000 type specimens in the museum’s Paleobiology collection. Each of these type specimens are the scientific ‘name-bearing’ examples of their entire species. This status makes them invaluable research tools for scientists.

“This really emphasizes how important our specimen is — both historically and in the present — for dinosaur science.”  — Matthew Carano, curator of dinosauria NMNH

Because of their scientific importance, most of these type specimens are kept off-display in secure cabinets and drawers. But museum visitors are able to see the historic Allosaurus type specimen in the museum’s Deep Time Hall of Fossils. The Allosaurus is  displayed alongside several of its contemporaries from the Jurassic, including the type specimen of its fossil foe, the plate-backed, spike-tailed Stegosaurus, and the sauropods Diplodocus and Camarasaurus.
The museum’s Allosaurus fragilis type specimen is notable because all of its bones came from a single Allosaurus. Many other Allosaurus skeletons are composites that incorporate bones from several different individuals. USNM V 4734, Department of Paleobiology, Smithsonian Institution. Photo by Mike Gaudaur

The exhibition’s Allosaurus mount, which contains the animal’s actual 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 Smithsonian’s 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 Gilmore’s times.”

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