Behind the Glass — Brontotheres


Mondays are quiet here in the public galleries since the museum is closed to visitors.  So we took the opportunity to squeeze through some tight wall spaces and clamber into an exhibit case for an official photo shoot for YPM VP 12048, the type specimen for Brontops robustus.  The pebble-strewn ground is a lie.  It is actually a perilous game of walking on thin ice:  keep your weight on the bouncing planks of plywood, avoid falling through the chicken wire!  Of course, all those darned loose rocks covering everything make it impossible to see the difference. . . . . . Image credit: Yale Peabody Museum / Curious Sengi.


Up close and personal.  This animal belongs to the Family Brontotheriidae.  Brontotheres are odd-toed ungulates (perissodactyls) and greatly resemble rhinos; however, modern analysis shows that this extinct lineage of mammals are most closely related to horses (Benton 2005).  Image credit: Yale Peabody Museum / Curious Sengi.


Though a few areas of this skeleton may be reconstructed, what you see on display here is the real fossil!  This well-preserved and largely complete specimen was discovered in 1875 near Chadron in the northwest corner of Nebraska in Oligocene aged deposits (Osborn 1929).  Image credit: Yale Peabody Museum / Curious Sengi.


Brontotheres (sometimes called by their older name, titanotheres) are the subject of a richly illustrated, two-volume masterwork by American Museum paleontologist Henry Fairfield Osborn (1857 – 1935).  The exact specimen on display today is reconstructed here in an illustration originally published by O.C. Marsh in 1889.  Image credit: Osborn 1929.


The skeleton was actually mounted for display in 1916 under the direction of Richard Swann Lull (1867 – 1957), who studied under Osborn.  Unlike the static standing pose in the Marsh illustration, Lull opted to capture the moment of a charging run, with the pert little tail in the air with rhino-like indignation.  This exact same pose can be seen on display.  When Lull measured the skeleton after it was mounted, he reported the height at the shoulder to be 8 feet, 2 1/2 inches (2.5 meters).  Image credit: Osborn 1929.


Fanciful reconstruction of life in a brontothere herd.  There used to be very different grazers out there on the Great Plains!  Image credit: Restoration by Erwin Christman & Charles R. Knight, reproduced in Osborn 1929.


Benton, Michael.  2005.  Vertebrate Paleontology, third edition.  Oxford:  Blackwell Publishing.

Osborn, Henry Fairfield.  1929.  Titanotheres of Ancient Wyoming, Dakota, and Nebraska, Vol. 1.  Washington, D.C.:  United States Government Printing Of


Digging Holes


Painted Desert of Petrified Forest National Park in Arizona.  The distant skies are filled with virgas, rain that evaporates before it reaches the ground.  Image credit: Curious Sengi.

This post is part of a series commemorating the 150th anniversary of the Yale Peabody Museum of Natural History.  You can read about the first specimen to enter the Vertebrate Paleontology collection here.  This story is about the most recent fossils to enter the collections — specimens that were collected just over a month ago in May and June 2016 during a field expedition to the Triassic rocks of Petrified Forest National Park, Arizona.   

Our dig site is marked by a dark blue tarp, a faint pinprick of artificial color in the Painted Desert.  At this point, we had already trudged over a mile through the trackless desert:  picking our way between the low scrub, avoiding rattlesnakes, and using a distant red-lipped hill as our only bearing.  Now we stood at the edge of badlands, where the fossils are.  The heat of the day is rising.  And that blue tarp is still painfully far away.

No sane human being would be out here.


The black arrow marks the location of the blue tarp that covers one of the multiple dig sites worked during the 2016 field expedition.  Image credit: Curious Sengi.

In our heat-addled hallucinations, we see the dreamscape of the desert, where gypsum erupts from the red earth like misshapen white molars or glittering panes of broken glass.  Millions of years of sediment deposition stand out in vivid colors, much too reminiscent of seven-layer dip and Neapolitan ice cream — trivial pleasures in an endless panorama.  Fat horny toads blink their stoic welcome.  Small lizards eye us suspiciously and make their challenge with jerky little push-ups before losing their nerve and diving for cover.  Lanky jackrabbits flash across the hills and disappear like omens.  Vampiric winds suck the moisture from our lips.  Dust devils gather.  When it stops, the cedar gnats come.  Bone chips weathering out of a hillside metamorphose into wishful thinking with the changing light.  Black zigzag lines on a pale potsherd is a startling reminder that we were not the first to venture out here.  But we are here now, driven by the hope of finding ancient beasts beyond all imagining.


Colorful layered sediments. Image credit: Curious Sengi.


Native American potsherd discovered while hiking. All archaeological artifacts found in the park are photographed, given GPS coordinates, and reported to park officials. The artifacts themselves are left untouched. Image credit: Curious Sengi.

The desert is a ravishing world that simultaneously destroys and restores.  For those moments of absolute beauty and discovery, we gladly welcome all the associated abuses it renders upon us.  After all, we are far away from the annoyances of home and office.  These are the few precious weeks out of every year we have in order to collect.  Collecting fossils is, of course, always a grand adventure of luck, sharp eyes, and digging holes.  But each expedition is just a beginning, the very first unfolding of multiple layers of discovery.

It starts with your eye catching something a little different, something a bit unusual and curious.  Perhaps it is the color or texture or shape — even just a feeling — that draws you to a piece of bone on the ground surface.  Other times, it is stunningly obvious:  a tooth with glossy enamel shining on the surface of rock pulled out from a quarry.  But for the most part, all you can know is that this is a fossil.


A little spot of homemade shade is a respite from a full day in the sun and wind. Image credit: Curious Sengi.


Life under the tarp.  Fossil preparator Christina Lutz works on undercutting a plaster jacket. Image credit: Curious Sengi.


Big bone weathering out the side of a hill. Image credit: Curious Sengi.


Yale Peabody Museum’s chief fossil preparator, Marilyn Fox, puzzles over the big bone. After brushing away the dirt and layer of bone weathered into dust, some shapes begin to take form.  Even so, the identity of the fossil remains a mystery.  Image credit: Curious Sengi.

Our priority in the field is to bring fossils back safely to the museum.  The care and preservation of specimens begins out there under the sun and blowing dust.  A touch of archival glue might help consolidate fragile pieces together.  Loose specimens are wrapped in packets of toilet paper and aluminum foil.   Larger specimens or bone embedded in the matrix are given a generous buffer of surrounding rock before being encased in hard protective plaster jackets.  Everything is meticulously labelled with field numbers and recorded with good locality data.  Always, good locality data.


Some of the treasures brought back from the expedition. These plaster field jackets cover and stabilize fossils that remain embedded in rock. Collectors mark approximate areas where bone is located in the block. Image credit: Curious Sengi.

These bundles return to the museum, often with very little idea of what the bone is or what kind of animal it belonged to.  That second moment of discovery comes when the fossils are prepared out of the rock, unveiling the extent of their shape and identity.  It takes skill and patience to prepare fossils, so this moment might be delayed by months or even years.  Even then, careful preparation might only reveal that an unidentifiable bone shard is just an unidentifiable bone shard.  Stunning or not, all of these specimens will eventually be accessioned into museum records and properly housed to ensure their long-term preservation.

The next moments of discovery are potentially infinite.  What can we learn from this specimen?  What does it say about anatomy or ecology or geological processes?  This moment could come from an observation waiting to be made tomorrow.  It could also stretch off into the future as generations of researchers find new questions to ask and innovate better ways of extracting information.  The vertebrate paleontology collections at the Yale Peabody Museum have the benefit of a long history — specimens that were discovered over a century ago have not exhausted their scientific value and are now being investigated using novel technologies, such as microCT scanning, that were beyond the wildest dreams of their original collectors.


Some dig sites contained bone encrusted in an unknown material similar to oxidized iron. Preparator Christina Lutz is experimenting with chemical methods to remove this layer. Research in museums also includes discovering better ways to prepare, conserve, and preserve specimens. Image credit: Curious Sengi.


Specimens fresh from the field. Image credit: Curious Sengi.

We have now returned as collectors ourselves.  Even at our desks and computers, we feel a fellowship with all those who experienced the beauty and brutality of the desert in search of fossils.  We also feel a certainty that those long-dead collectors would be as grateful as we are, to know that our contributions will endure in the hands of dedicated museum staff and curious minds yet to arrive.  These specimens will be here, waiting for their many moments of discovery to unfold.

And we also wait here, watching the calendar for the next time we can step out into field.


The joys of camp. Some of the field crew prepare dinner. Members of our expedition came from all backgrounds and experience levels. The team included undergraduate students, volunteers, museum professionals, and academics. Image credit: Curious Sengi.


Until next time. . . . . Image credit: Curious Sengi.

Special thanks to Marilyn Fox and Christina Lutz for their help in preparing this post.

Part & Counterpart


Two halves of a split rock show two sides of the same fossil — the part and counterpart — of Diplurus newarki, a Late Triassic coelacanth fish from New Jersey. This fossil represents a number of different individuals. Image credit: Yale Peabody Museum / Curious Sengi.



The tail of one Diplurus arching towards the left. The faint impression of scales are also present. Image credit: Yale Peabody Museum / Curious Sengi.



An even closer detail of the tail fin shows the individual little bones that make up the fin rays. Image credit: Yale Peabody Museum / Curious Sengi.



Detail of the trunk skeleton shows, among other things, distinctive “Y” shaped bones. These are either neural or haemal arches.  The neural cord (in neural arches) or the major blood vessels running the length of the body (in haemal arches) thread through this protective arcade of bone like a thread through a needle’s eye.  Image credit: Yale Peabody Museum / Curious Sengi.

Origins of an Idea: Stupid Stegosaurus Needs A Second Brain

Larson_Far Side_dinosaurs-picture-is-bleak

Image Credit: Gary Larson via Lapidary Apothegms.

In 1930, English geologist John Parkinson described a species of stegosaur in less than savory terms:

The reptile. . . .belonged to the most uncouth group of all the stegosauria or armoured dinosaurs. . . . Stupidity and slowness seemed to be stamped on every bone of the beast.

One detail, common to the stegosaur type of dinosaur. . .  is the expansion of the canal, which carries the great nerve (the neural cord) from the brain through the arch of the vertebrae, to the sacral or hip region, an expansion so enormous that the enclosed nerve matter exceeded in size that of the brain itself. . . .

In fact, the reptile had two brains. . . . [and the hinder one] looked after the functions of nutrition, digestion, and propagation, practically all that life’s daily routine required in a stegosaur.


Stegosaurus is a sizable beast, with the largest individuals of certain species growing to nearly 30 ft (9 meters) in length. In comparison to this enormous bulk, the head does appear ludicrously tiny in proportion. Image credit: Yale Peabody Museum / Curious Sengi.

Of all the dinosaurs known to us, Stegosaurus seems to be singled out for being particularly stupid.  So stupid, in fact, that this iconic beast required a second brain in its hip to muddle through life.  It is a strange snippet of information that continues to persist. . . . . so where did this idea come from?


The cranial cavity that once contained the brain is colored red in this drawing of a cross-sectioned stegosaur skull.  Marsh noted the general elongate shape of the brain, enlarged optic lobes suggesting the relative importance of vision in these animals, and small cerebral hemispheres.  Image credit: public domain via Wikimedia Commons.


Original collection labels for some of the Stegosaurus fossil material collected for O.C. Marsh.  Note the label on the right describing a natural brain cast, or endocast.  Image credit: Yale Peabody Museum / Curious Sengi.

The first stegosaurs were discovered from Late Jurassic (~150 ma) rocks in Colorado by paleontologist O.C. Marsh (1831 – 1899).  If not otherwise preoccupied with his role as co-villain in the infamous Bone Wars, Marsh ventured into new realms of inquiry including the study of endocasts, which are molds of internal, hollow spaces — in this case, spaces in the skull or vertebrae once occupied by the brain and other nervous system structures.  Looking at these ancient brains not only gave a general sense of their size, but could also reveal finer details indicating heightened development of certain senses such as vision or olfaction.  Marsh found at least one natural fossil endocast of a stegosaur brain.  Based on some quick calculations, he remarked that if a stegosaur and a modern alligator were scaled to the same body size, the stegosaur brain would be 1/100th the size of the alligator’s.  This led to the grim conclusion that:  “Stegosaurus had thus one of the smallest brains of any known land vertebrate (Marsh 1896).”


Sowing the seeds of suspicion:  comparatively massive white plaster cast of the stegosaur sacral cavity in the background with a natural stone endocast of the brain cavity in the foreground.  The plaster cast captures the enlargement of the spinal cord as it passed through the sacral (i.e., pelvic) vertebrae.  Marsh believed the sacral cavity housed a secondary neural center that was an estimated 20 times larger than the brain.  U.S. quarter for scale.  Image credit: Yale Peabody Museum / Curious Sengi.

To make matters worse, Marsh made an artificial endocast in plaster of the sacral cavity, i.e., the hollow passage for the spinal cord in the vertebrae that are fused to the pelvis.  This cavity was unusually large, more so than would be expected.  While it was observed from a wide variety of vertebrates that the spinal cord bulks up where it sends off nerve branches to innervate the fore- and hindlimbs, the stegosaur’s enlarged neural cavity with its intervertebral bulges was exceptional.  The sacral cavity was estimated to be at least 20 times the size of the brain.

Marsh Stegosaurus Sacrum Plate

One of the plates used in Marsh’s description of Stegosaurus from the American West.  The top figures (2 & 3) show views of the plaster cast made of the sacral cavity, complete with the sideways bulging into the intervertebral space (labeled f, f’, and f”).  Figure 4 shows a schematic cross section of the relative size of the brain and sacral cavity.  Image credit: Marsh 1896.

Given this vaguely brain-shaped hollow and, more interestingly, a particular pattern of growth in size between juveniles and adults, Marsh described the sacral cavity as a “posterior brain case” and “a posterior nervous center” — thus, the notion of a Stegosaurus butt brain was born.

Marsh seemed content with equating the presence of a secondary nerve center with a “. . . . posterior part that was dominant,” which one could imagine referred to the great weight borne upon the hindlegs and the coordination necessary to swing the stegosaur’s spiked tail against foolhardy predators or rivals.  German scientists Branca and Waldeyer went so far as to ascribe a certain independence in function, affirming that this was indeed a proper “sacral brain” delegated to back-half duties:  digestion and sex.


A set of stegosaur sacral vertebrate.  The hollow through the middle shows the opening into the sacral cavity.  This specimen was also collected for Marsh.  Image credit: Yale Peabody Museum / Curious Sengi.

The role of intelligence — as interpreted through brain size alone — in the evolutionary succession of life on Earth was a particular obsession of the late 19th and early 20th century Western world.  The discord between the gargantuan body size of the dinosaurs and their pathetically small brains captured the public imagination.  It seemed like an obvious rationale for why dinosaurs went extinct.

More recent scientific studies have revisited the question of stegosaur brains and the results are much more nuanced.

Extrapolation from data collected from living reptiles showed that the vast majority of dinosaurs seemed to fall within the expected range of brain size to body mass proportions.  While the stegosaur brain remained somewhat below the expected prediction, its size was consistent with large animals enjoying an undemanding “slow, herbivorous lifestyle (Buchholtz 2012).”  Even if Stegosaurus was not catastrophically stupid, what about that “second brain”?


There was nothing bright going on the sacral cavity.  Even though paleontologists no longer accept the idea of a secondary brain, what occupied this space along with the spinal cord remains inconclusive.  Lateral view of sacral vertebrae with the internal cavity illuminated through the intervertebral spaces.  Image credit: Yale Peabody Museum / Curious Sengi.

Paleontologists today emphatically reject the notion of a “sacral brain.”  There are a number of hypotheses proposed for why stegosaurs possessed such enlarged sacral cavities, the most popular of which is that this space housed an agglomeration of tissue called a glycogen body.  Glycogen bodies are only definitively found in the sacral cavities of modern birds and consist of carbohydrate-rich cells.  While this structure has not been extensively studied, it is believed to provide metabolic support for the central nervous system, especially during the formation of myelin, a fatty layer of cells that insulate nerve fibers.  As living descendants of the dinosaur lineage, it seemed plausible that the avian glycogen body is homologous to mysterious item occupying the stegosaur’s pelvis.

Chicken Glycogen Body

The avian glycogen body is an oval-shaped mass on the spinal cord.  The function of this structure is not fully understood, but is probably involved in the metabolism of nervous system tissues.  Image credit: De Gennaro 1982.

It should be noted that sacral enlargements for a putative glycogen body are found only in stegosaurs and another heavy herbivore, those long-necked titans:  the sauropods.  However, neither are stegosaurs and sauropods closely related to each other, nor are they closely related to birds.  Dinosaurs that are in the direct line to modern birds, such as coelurosaurs, lack any kind of enlargement of the sacral cavity.  In the end, the question of why Stegosaurus had such a large hollow in its hip remains a dissatisfying enigma.  But, if anything, it definitely was not a brain with an independent agency as Branca and Waldeyer believed.

Stegosaurs were certainly not very bright, but they did quite well for several million years.  And that is considerably longer than the approximately 200,000 year history of anatomically modern humans and the current future we have set upon.

Preview of the new "Body Worlds" exhibit that will open at the Denver Museum of Nature and Science. Visit to museum on Tuesday, March 9, 2010. Central and peripheral nervous system. Cyrus McCrimmon, The Denver Post

Plastinated specimen of the human nervous system.  Note the thickening of the spinal cord where nerves for the arms and legs branch off.  This is the usual pattern in vertebrates.  From the “Body Worlds” 2010 exhibit at the Denver Museum of Nature and Science.  Image Credit:  Cyrus McCrimmon / The Denver Post.



Benzo, C.A. & L.D. De Gennaro.  1983.  “An Hypothesis of Function for the Avian Glycogen Body:  A Novel Role for Glycogen in the Central Nervous System.”  Medical Hypotheses 10:  69 – 76.

Buchholtz, Emily.  2012.  “Dinosaur Paleoneurology.”  In The Complete Dinosaur. 2nd edition.  M.K. Brett-Surman, T.R. Holtz, Jr., & J.O. Farlow, editors.  Indiana University Press.  Pp. 191 – 208.

De Gennaro, Louis D.  1982.  “Chapter 6:  The Glycogen Body.”  In Avian Biology, Vol. VI.  D.S. Farner, J.R. King, & K.C. Parkes, editors.  Academic Press.  Pp. 341 – 372.

Galton, Peter M. & P. Upchurch.  “Chapter Sixteen:  Stegosauria.”  In The Dinosauria, 2nd edition.  2004.  D.B. Weishampel, P. Dodson, & H. Osmólska, eds.  University of California Press.  Pp. 343 – 362.

Griffin, Emily.  1990.  “Gross Spinal Anatomy and Limb Use in Living and Fossil Reptiles.”  Paleobiology 16 (4):  448 – 458.

Lull, Richard Swann.  1917.  “On the Functions of the ‘Sacral Brain’ in Dinosaurs.”  American Journal of Science 44:  471 – 477.

Marsh, O.C.  1896.  “The Dinosaurs of North America.”  Sixteenth Annual Report of the U.S. Geological Survey, Pt. I:  133 – 244.

Parkinson, John.  1930.  The Dinosaur in East Africa:  An Account of the Giant Reptile Beds of Tendaguru, Tanganyika Territory.  H.F. & G. Witherby.

Notes from the Field No. 2: Erstwhile Pets

Scarritt Pocket

Mammal fossils lured paleontologists to Oligocene age rocks in Patagonia of Chubut Province, Argentina. The deposits pictured here were discovered by G.G. Simpson heading the Scarritt Expedition in 1934.  This photograph comes from a modern paleontological expedition revisting the area.  Image credit: Vucetich et al. 2014. “A New Acaremyid Rodent (Caviomorpha, Octodontoidea) from Scarritt Pocket, Deseadan (Late Oligocene) of Patagonia (Argentina).”  Journal of Vertebrate Paleontology 34 (3): 689 – 698.

In the 1930s, the reknowned American paleontologist George Gaylord Simpson (1902 – 1984) led a number of fossil hunting expeditions with the American Museum of Natural History to Patagonia in the southern end of South America.  Simpson was very much interested in an assemblage of ancient mammals living in “splendid isolation” on the island continent of South America.  His research centered upon these endemic radiations and their eventual fate when a narrow landmass, the Isthmus of Panama, arose at the end of the Pliocene (approximately 3 million years ago) and began the Great American Faunal Interchange.  While searching for evidence from this epic story of South-meets-North, the expedition lightened their days enjoying the antics of local wildlife they adopted as camp pets.

The vast plains of Patagonia are a barren and savage waste in which man seems an interloper.  Here in the far south of South America nature never smiles. . . Yet Patagonia has its own children, living in constant fear and combat, but somehow contriving to flourish and finding in this desolation a home suited to their own wild temperaments. . . .

Simpson in the Field with Jacket

Simpson at the dig.  A skeleton is carefully excavated, covered in shellac, and bandaged for safe transport.  Image credit: Simpson 1932.

We caught one of the babies [a Darwin’s Rhea, Rhea pennata] and christened him Charita. . . . [he] soon forgot his brothers and sisters and lived with us contentedly, a silly creature with feet much too big for it, its body the size and shape of the egg from which it came (where the neck and legs fit in I do not see), covered with soft down, dark brown and striped with white like a skunk.  His idea of heaven was to wedge himself tightly between two hot pans beneath the camp stove.  When deprived of his sensuous pleasure, he divided his time between trying to crawl into our pockets and trying to scratch his head, laudable ambitions neither of which was ever wholly achieved. . . . He used to sleep with one of us, and soon became a real member of the family.  His cry was a sad whistle, slurring down the scale and ending with a pathetic tremolo. . . . he would come running whenever we called him and would carry on long conversations with us.

Charita the Rhea Chick

Expedition members tended to name their pets after the local language — in this case, “Charita” referred to “ostrich chicks in general.”  Of course, Charita was not actually an ostrich, but a related ratite indigenous to South America known as a rhea.  Drawing by E.S. Lewis.  Image credit: Simpson 1932.

Our long favorite was a pichi [i.e., armadillo] named Florrie. . . . She came to tolerate us as servitors but never displayed any demonstrative affection.  One can no more pet an armadillo than one can pet an egg or, more aptly, a tortoise, and her own attitude was always one of vapid selfishness.  Yet she fully earned her keep.  As she wallowed in a saucer of condensed milk we laughed more at than with her.  She never learned to lap it up cleanly with her long tongue, but must always get her sharp, flexible snout in it too, so that attempts to breathe resulted in convulsive coughs and mighty blowing of bubbles.  She would start to wander off, then suddenly remember the milk, dash back to it in the most business-like way and start drinking again, only to lose interest, wander off again, and repeat the whole process several times.

There was always something vague about Florrie.  Her thick skin seemed to be an index to her mentality and emotions.  Almost the only real emotion she betrayed was when first captured.  Then, if touched, she would suddenly jump, at the same time emitting a convulsive wheeze, a maneuver as disconcerting as the explosion of a mild cigar.  Later she ceased to bother.  If she wandered off when let out, it was rather from absent-mindedness than from any active dislike for our society.  She seemed to think with her nose, and when thus let out for exercise she would trot busily from bush to bush, poking her nose into the ground beneath and sniffing violently.  Once she got away altogether and for several days we mourned her for lost, when one morning she wandered back into camp with her usual air of preoccupation.  The cook, whose special friend she was, swore that she returned for love of us, and another said she had returned for free meals, but I maintain that she had simply forgotten that the camp was there two minutes after she left it, and stumbled on it again quite by accident in the course of one of her sniffing parties.

Florrie the Armadillo

Drawing by E.S. Lewis.  Image credit: Simpson 1932.

These erstwhile pets shared in the daily life of the expedition.  What, if anything, was planned for their ultimate fate is a bit more ambiguous.  Simpson devotes a great deal of space in this popular account to the culinary merits of the local wildlife (a hallowed tradition in scientific expeditions) and both rheas and armadillos were eaten regularly.  Whether the men planned to abandon the animals, eat them, take them back to New York, or have them prepared as museum specimens, that decision soon became moot.  For “. . . .Charita met an untimely end.  He developed an unwholesome appetite for kerosene and, one day, finding a whole pan of this delightful beverage unguarded, he overindulged.  All afternoon, he wandered about vaguely as if something was very much on his mind, or stomach, and next morning he was dead.”  Likewise, Florrie, who was a cheerful presence in camp for several months, ended up being accidentally crushed to death.  Despite these unhappy ends, it is clear that the hapless bumblings of animals like Charita and Florrie were the focus of much entertainment and affection during the long months of isolation grueling in the field.  

Quotation Source

Simpson, George Gaylord.  1932.  “Children of Patagonia.”  Natural History 32 (2):  135 – 147.

Small beginnings. . . .

This post is part of a series commemorating the 150th anniversary of the Yale Peabody Museum of Natural History.  We will be uncovering the stories behind the first specimens to enter the Peabody collections, as well as some of the most recent.

First specimen acquired for Vertebrate Paleontology:  YPM VP 2125 Plateosauria


YPM VP 2125 Plateosauria. Image credit: Yale Peabody Museum / Curious Sengi.

It is no surprise that this assemblage of rocks does not look like much:  they were blasted out of a 23-foot hole by Solomon Ellsworth, Jr. of East Windsor, Connecticut in 1818.  Ellsworth was constructing a well on his property when he noticed the chalky white bones in the rubble of dark red sandstone.

The unusual find was passed around in local circles of learned men, including a number of professors at the Medical Institution of Yale College, who came to the lukewarm conclusion of “. . . .the possibility that they might be human bones, but did not consider the specimens as sufficiently distinct to form the basis of a certain conclusion (Smith 1820).”  In 1821, a letter was published in The American Journal of Science and Arts that expressed the opinion of Dr. Porter, who was present on Ellsworth’s property when the bones were found.  He deduced the remains came from “some animal. . . . about five feet in length.  The tail bone was easily discovered by its numerous articulations distinctly visible. . . . and by its being projected, in a curvilinean direction beyond the general mass (Hall 1821).”


Many elements — such as those in this right forelimb — have pasted labels, which is not standard for research specimens, but might perhaps reflect this fossil’s history as a teaching specimen. Image credit: Yale Peabody Museum / Curious Sengi.

Another redescription appeared in the same journal decades later in 1855.  Jeffries Wyman stated that the tail vertebrae most resembled a crocodile and noted the similarity of the hollow limb bones to those of birds, both strikingly prescient observations.  The mysterious remains were finally declared to be a Triassic dinosaur in 1896 by O.C. Marsh (1831 – 1899), that grandiose, bearded professor of paleontology at Yale and ambiguous hero of the heady Wild West days of dinosaur collecting.

The exact identity of the fossil has bounced around, but it is currently recognized as an indeterminate sauropodomorph in the clade Plateosauria.  This obscure dog-sized beast was part of a lineage leading to the sauropods, the behemoth long-necked herbivores we fondly remember as Brontosaurus, Diplodocus, Titanosaurus, and others.  From small beginnings arose some of the largest animals to ever live upon this Earth.


One of the vertebral elements with an illustration of a reconstructed plateosaur skeleton. Image credit: Galton 1971 via Carroll, R.L. 1988. Vertebrate Paleontology & Evolution / Yale Peabody Museum / Curious Sengi.

Despite the rather humble appearance of these bones blown out of Ellsworth’s well, their scientific relevance has been long-lived, with the specimen being cited in publications as recently as 2012.  The bones also have the historical distinction of being the earliest discovered dinosaur fossils in North America verified by recorded literature and an existing specimen.

So how did this subject of lively discussion amongst the physicians, professors, and learned citizens of early 19th century Connecticut find its way into the Yale Peabody Museum?  The world of science was still relatively small and intimately connected by communities of correspondence, so it was a matter of time before the news reached one of America’s most influential men of science, Benjamin Silliman (1779 – 1864).  (Incidentally, he was also the founder and editor of The American Journal of Science and Arts which published the first accounts of the bones.)  As a professor of chemistry, geology, mining, and pharmacy at Yale College, Silliman for many years kept a “Mineral Cabinet” that was filled with samples and specimens for teaching.  Undoubtedly recognizing some potential, he acquired the fossils for the cabinet.


Benjamin Silliman was about to start a career as a lawyer when he was approached with an offer of professorship in chemistry and natural history.  The only difficulty was that Silliman had no training in science!  But the young man met the challenge with intelligence and energy, and within a few years, delivered the first lecture on science ever given at Yale.  As a respected geologist, teacher, and liberal-minded reformer, Silliman became an influential figure in 19th century intellectual life.  Here, he has inked his own initials, “B.S.”, on the back of this specimen. Image credit: Yale Peabody Museum / Curious Sengi.

Over the years, the natural history collection at Yale grew in size and matured in ambition.  It was time for the university to have a proper museum for the benefit of both its students and the public.  Sensing that the rich, newly-discovered fossil beds of the American West would soon overwhelm the current facilities, Silliman made some initial overtures to wealthy philanthropist George Peabody.  The request seems to have fallen flat; however, it was Silliman’s student, O.C. Marsh, who was finally able to prevail.  By the time Marsh secured a $150,000 gift for what would become the Yale Peabody Museum in 1866, Silliman had been dead for two years.  But it was Silliman’s cabinet that formed the core of the museum collections, including those curious white bones embedded in red Connecticut sandstone which would be the first specimen to enter a newly formed Division of Vertebrate Paleontology.  From an early American teaching collection arose a modern museum with over 13 million specimens — yet another great rise from a small beginning.


Special thanks to Dan Brinkman for his assistance in researching this post.

Come see an exhibit celebrating the history of the Yale Peabody Museum and its treasures from 2 April 2016 until 8 January 2017.



Delair, Justin B. & W.A.S. Sarjeant.  2002.  “The earliest discoveries of dinosaurs:  the records re-examined.”  Proceedings of the Geologists’ Association 113:  185 – 197.

Galton, Peter M.  2012.  “Comment on Anchisaurus Marsh, 1885 (Dinosauria, Sauropodomorpha): proposed conservation of usage by designation of a neotype for its type species Megadactylus polyzelus Hitchcock, 1865.”  Bulletin of Zoological Nomenclature 69 (3): 229-231.

Hall, John.  1821.  “Fossil Bones found in East-Windsor, Connecticut.”  The American Journal of Science and Arts 1 (III):  247.

Hanrahan, Brendan.  2004.  Great Day Trips in the Connecticut Valley of the Dinosaurs.  Perry Heights Press.

Remington, Jeanne E.  1977.  “Curatorial Staff and Other Scientists Associated with the Peabody Museum of Natural History and Its Antecedent Collections, 1802 – 1977.”  Discovery 12 (3):  31 – 42.

Smith, Nathan.  1820.  “Fossil Bones found in red sand stone.”  The American Journal of Science and Arts 1 (II):  146 – 147.

Wyman, Jeffries.  1855.  “Notice of Fossil Bones from the Red Sandstone of the Connecticut River Valley.”  The American Journal of Science and Arts 2 (XX):  394 – 397.

Yates, Adam M.  2010.  “A Revision of the Problematic Sauropodomorph Dinosaurs from Manchester, Connecticut and the Status of Anchisaurus Marsh.”  Palaeontology 53 (4):  739 – 752.