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Cataloging the Archives: Three Fine Trikes

Another in a series of blog posts relating to the museum's "cataloging the archives" project

Ask children what their favorite dinosaurs are, and it's almost guaranteed that Triceratops (refer to them by their nickname, Trikes, and you'll earn tons of street cred) will be on the list. The three-horned, frilled wonder is one of the most recognizable creatures of the Cretaceous. Many a visitor has walked by the Triceratops display here in the Valley Life Sciences Building's Marian Koshland Bioscience and Natural Resources Library. Over time, the display has grown, not only to include more skulls, but to tell a bigger story. Now there are three skulls in the display, each with its own interesting history, but when taken together the tale reaches almost epic status (okay, "impressive" status).

Ruben at locality2

 

The largest of the skulls is UCMP specimen 113697, also known as "Ruben's Trike." While on a UCMP field expedition to Montana and neighboring states in July, 1970, paleontology graduate student John Ruben (now a professor in the Department of Zoology, Oregon State University) discovered the skull in the roughly 68-million-year-old rocks of the Hell Creek Formation of eastern Montana. The Hell Creek is one of the most fruitful formations for Trike discoveries, and if you've done field work in the Upper Cretaceous of Montana and haven't come across some part of a Triceratops, you're doing something wrong.

John Ruben (black hat) at his "Ruben's Trike" locality, V75046, where the skull, UCMP 113697, was found, McCone County, MT.

 

The medium-sized Triceratops skull, UCMP 136306, is also known as the "McGuire Creek Trike" since its discovery in badlands of the Hell Creek Formation exposed in the vicinity of this creek drainage in McCone County, Montana. Weathered fragments of bone or "float" from the skull were first sighted by paleontology undergraduate Wayne Thomas in the summer of 1984 on a UCMP field research trip. Further excavation by UCMP Assistant Director Mark Goodwin and crew that summer confirmed Wayne's discovery was a nearly complete juvenile Triceratops skull. The find was exciting in itself, but it also helped fill in some holes in the understanding of Triceratops growth from baby to adult (known as ontogeny) and generated new research by Goodwin, his colleague Jack Horner from the Museum of the Rockies, and their students. For more information on Trike ontogeny, stay tuned for a future blog entry centered on this exact topic.

The smallest of the Trike skulls, UCMP 154452, was found in the Hell Creek Formation (see a trend?) of Montana by long-time UCMP field associate and collector, Harley J. Garbani, in 1995.

When Harley came across the specimen, he first identified it as a possible pachycephalosaur because the tiny brow horn so closely resembled the horns and knobs seen ornamenting the back of the skulls of pachycephalosaurs, or "dome-headed" dinosaurs. Being a very young individual, likely less than a year old, the skull showed features not seen before on a Trike, was very delicate, and in many pieces. Trying to determine what some specimens are from many fragments can be a tedious and insanity-inducing ordeal (ask any fossil preparator).

After corresponding with, and providing pictures to, Mark Goodwin and Professor Bill Clemens, the specimen was correctly identified and also keyed Goodwin into finding a near identical isolated postorbital or "brow" horn from the skull of another baby Triceratops in the UCMP collections.

Baby trike collage 1

Left: HJG 1030, the Baby Trike Site. Photo by Bill Clemens. Top right: A portion of Harley Garbani's field notes. He crossed out "Dome-Head" (i.e., pachycephalosaur) after learning it was a baby Triceratops! Bottom right: An excerpt from a letter that Harley wrote to Bill Clemens. He knew he had something important, and very quickly corresponded with the right parties to learn why. Image courtesy of Bill Clemens.

Baby trike collage2

Top left: Photo of a table top covered with the bones of the baby Trike skull discovered by Harley Garbani. Bottom left: Reconstruction of baby Trike. Photo by Dave Smith. Right: Assistant UCMP Director and dinosaur paleontologist Mark Goodwin working on the baby Triceratops skull. It was prepared, molded, and cast so that an accurate reconstruction (on exhibit in the Biosciences Library) could be made available for research and display. Images of Mark Goodwin and skull bones courtesy of Bill Clemens.

 

Harley’s discovery was a game-changer since it was, and still is, the smallest Triceratops skull and by inference, the youngest yet known. Together, these three skulls tell a story about skull development and growth in a dinosaur that was named by O.C. Marsh of the Yale Peabody Museum over 120 years ago!

UCMP paleontologists are still discovering new things about this very popular dinosaur. Fossils are often known for whatever novel thing they can tell us, but sometimes a seemingly small and, at first, very fragmentary fossil becomes significant when studied in the context of other fossils and when you hear the story behind its discovery. These Triceratops skulls are interesting on both counts!

Fish in the UCMP

Salmonid FossilIt is pretty unusual to see fish in the UCMP. It’s not that we don’t have any fish specimens — we have over a million fossilized fish fragments. It’s just that none of our museum scientists focus on fish, and so the museum’s fish parts tend to stay in the cabinets. But this past summer, Ralph Stearley of Calvin College visited the UCMP, and he did a little fishing.

Ralph pulled some spectacular specimens from the murky depths of the cabinets. The two specimens shown here are exceptional — nearly all the bones are in place, and one of the specimens even has imprints of scales! It is really rare for fish to fossilize like this — most of the time, fish break apart into individual bones and tiny scales.

These two specimens are salmonids. They are related to salmon, char, and trout — their closest living relative is probably the Dolly Varden. They lived 15-10 million years ago, in the ancient lakes that back then dotted Western Nevada. They were collected by UCMP curator Howard Hutchison in 1975, in an area called Stewart Valley. This site contains fossilized vertebrate, insect, fish, and plant material — it is rare to find so much taxonomic diversity in one place. Hutchison and his colleagues really got a sense of the entire fauna that once inhabited the area.

Ralph was excited to find these salmonid specimens in our collection — he and his collaborator, Gerald Smith of the University of Michigan, study the biogeographic history of salmonid fish. These specimens provide evidence that salmonids once lived in Western Nevada. For Ralph and Gerald, these fish are definitely keepers.

Salmonid Fossil Salmonid Head Scales Fish fossil

Rudists

RudistNot to be rude, but what in the world is a rudist? Well, rudists are invertebrates, and they lived in the world’s oceans during the late Jurassic and the Cretaceous, about 150-65 million years ago; they are now extinct. They are bivalves — the name means “two shells.” Today’s familiar bivalves, clams and mussels, have two shells that are more or less symmetrical. But rudists were a bit unusual: their two shells were very different from each other. One shell was either conical or coiled, and it was attached to the ocean floor (or neighboring rudists). The other shell sat on top, like a little hat. The organism lived inside. They were probably filter feeders, feeding on plankton in the water, like many other bivalves today.

Rudists would grow on top of one another and form rudist reefs. They were the major reef-building organisms of their time — corals weren’t so abundant back then. Reefs are really important habitats for other marine organisms, like fish and crustaceans. So rudists played an important role in the ancient ocean.

So if rudists were so ecologically important, how did they get stuck with such an odd name? Lamarck dubbed them rudists in 1819, but it’s a little unclear what he meant. The Latin word rudis means rude, raw, or uncultivated. The Latin word rudus means rubble, or broken stone — specifically, the stones that made up Roman roads. Rudists do seem sort of coarse and unrefined, and they do look an awful lot like stones. But who knows what Lamarck was thinking.

This fossil rudist was found in Chiapas, Mexico. Learn more about rudists on the UCMP’s rudist page.

Meet a mosasaur

Mosasaur

Imagine you are driving down I-5, just north of Bakersfield, in California’s hot and dusty central valley. Except that it’s the Cretaceous Period, 80-65 million years ago, and the central valley is actually an inland sea. And instead of seeing cows standing by the side of the highway, you see mosasaurs swimming through the salty water.

Mosasaurs were marine reptiles that lived during the late Cretaceous, in oceans all over the world. They had fins on their long bodies, and sharp teeth in their long jaws. They ate fish, ammonites, and possibly even other mosasaurs. Lucky for us, mosasaurs are now exctinct — they died out with the dinosaurs at the end of the Cretaceous.

This particular fossil was found in 1937 by a high school student named Allan Bennison. Just the previous year, Bennison found the first dinosaur fossil in California. He used to ride his bicycle from his home in the San Joaquin Valley to the Moreno formation, where this fossil was found, a distance of 35 miles. Bennison went on to study at Berkeley, where he earned a degree in paleontology in 1940. This species was named after him: Plotosaurus bennisoni.