Blogs from our Scientific Researchers

Carnegie Museum of Natural History is home to active research and vast scientific collections. Our scientific researchers regularly contribute to the blog at the museum.

August 10, 2020 by wpengine

Meet Ainsley Seago, New Associate Curator of Invertebrate Zoology

Dr. Ainsley Seago (pictured with *Vespula germanica*, one of Australia’s many, many invasive species). Photograph by Jude Keogh.

Dr. Ainsley Seago studies the evolutionary history of beetles, from systematics and diversification of Staphylinoidea (rove, carrion, and fungus beetles) to the evolution of iridescence in Curculionoidea (weevils and their relatives). She has used everything from rotting squid traps to synchrotron radiation to better understand beetles in all their glory, but believes that the most important tool of all is a strong museum collection. Dr. Seago is thrilled to work with the CMNH collection and exhibit teams to bring the museum’s outstanding invertebrate collection to a wider audience, while using it to support research in Pittsburgh, the US, and beyond.

Dr. Seago is originally from Tacoma, WA, and has just returned to the U.S. after 12 years in Australia.

Abstract of recent research (bearing in mind that I have a very loose grasp on what 8th graders are up to these days)

Australian stag beetle, *Lamprima aurata* (Coleoptera: Lucanidae). Photograph by Lauren Drysdale.

Among the world’s beetle species are hundreds of “living jewels,” insects with stunning jewel-like colors or shining golden armor. These so-called structural colors arise from nanoscale patterns in the exoskeleton, from variations in the thickness of chitin layers to intricate three-dimensional crystal lattices. Because they’re made by fixed structures and not chemical pigments, these types of insect color last indefinitely– even through fossilization.

Within the last 20 years, scientists have learned that several species of weevils (not to mention butterflies and longhorn beetles) make their glittering, sequin-like colors with microscopic lattices called three-dimensional photonic crystals. We have also learned that these photonic crystals can generate different colors depending on how tightly spaced they are. However, the evolutionary origins of this type of iridescence have never been explored.

Iridescent scales of *Pachyrhynchus orbifer* (Coleoptera: Curculionidae). Photograph by Ainsley Seago.

Working with researchers from Yale-NUS (Singapore) and the Australian National Insect Collection (Canberra), I have conducted the first ever research placing a wide variety of photonic crystal structures from across the weevil family tree in an evolutionary (“phylogenetic”) context. The surprising result was that these crystals, found in hundreds of species of weevils, all derive from a single ancestral origin. Although three-dimensional photonic crystals have evolved repeatedly in insects, they appear to have evolved only once in weevils. The weevil lineages that gained these iridescent crystals then diversified rapidly, suggesting that the jewel-like colors aren’t just beautiful, they also confer a distinct evolutionary advantage.

Mobilizing Millions of Marine Mollusks: Seashells by the Eastern U.S. Seashore

“What a pretty seashell, where did it come from?”

Perhaps the most important information that natural history museums keep about their specimens is where they came from. For many researchers, locality information is more important than the specimen itself. The specimen is useful to verify correct identification, but you can’t look at a specimen to determine where it came from.

As more and more museums share their specimen databases on-line, locality information is being used to document changes in distributions of organisms, including new occurrences of invading species, range shifts due to climate warming, and the disappearance of species becoming locally extinct.

To facilitate uses of locality information, museums are scrambling to georeference their specimens. This term refers to the electronic pairing of the historic recorded location for each collected specimen with an established system of latitude and longitude coordinates. Georeferencing can be tedious and time-consuming, what with interpreting messy handwriting, dealing with misspellings, and tracking down obscure names, some of which have changed over time. Once I spent over an hour and got only two specimens georeferenced.

The US National Science Foundation (NSF) recognizes the importance of georeferenced specimens to facilitate understanding of where species occur and how their distributions change over time. Consequently, NSF has awarded $58,762 to Carnegie Museum of Natural History as one of 14 collaborating museums on a $2.3 million grant for a project titled: Mobilizing Millions of Marine Mollusks of the Eastern Seaboard. The project is spearheaded by Rudiger Bieler at The Field Museum in Chicago.

The main goal of the project is to georeference, and make available online, 535,000 lots representing 4.5 million specimens of marine mollusks (snails, clams, etc.) from the eastern USA. Only 15% of Eastern Seaboard mollusks in museums are currently reliably georeferenced. To facilitate georeferencing and promote standardization, each collaborating museum will focus on georeferencing all lots from particular geographical areas. Notably, for the first time, these museum records will distinguish between live- and dead-collected specimens, important information given that shells of dead mollusks sometimes persist for hundreds of thousands of years, and can be moved by currents and other animals such as hermit crabs. Whether or not a shell was collected alive is therefore crucial information for studies of biotic change using mollusks.

Two lots of East Coast USA seashells ready to georeference.

For CMNH, this award primarily means support for georeferencing our 11,436 lots of marine mollusks from eastern USA. In addition, we will catalog the eastern US part of our backlog, image relevant type specimens, create an exhibit, and, the aspect I am most excited about is creating an IPT, or integrated publishing toolkit, which will allow automatic updates from our in-house database to our web presence in the InvertEBase Symbiota portal.

The grant-funded new public display will interpret our biologically, commercially, and recreationally important marine mollusks from the Eastern Seaboard, and showcase mollusk diversity. The display will appeal to anyone who has beachcombed shells. Labels will describe how scientists use modern and historical specimens to study change in marine ecosystems over time. My hope is that visitors will learn that mollusks are diverse and beautiful, that museum collections are useful, and that evidence-based studies show ecosystem changes.

The Eastern Seaboard region includes 18 states, nearly 6,000 km of coastline, and about 3,000 molluscan species. Boundaries, from Maine to Texas, stretch from the shore outward to the edge of the U.S. Exclusive Economic Zone. The 14 collaborating U.S. collections contain 85% of all Eastern Seaboard marine mollusk museum holdings. These museum holdings average 8 specimens per lot – a lot is one species from one place at one time.

One hundred million mollusk specimens have been documented in natural history collections across North America. Each mollusk species in these collections average 1100 individuals, revealing geographic and morphological variation, and making mollusks among the best sampled group of metazoans, or multi-cellular animals. So far, freshwater and terrestrial mollusks have dominated digitization efforts of mollusks. This project is the first to focus on marine mollusks.

Shells are bio-archives. Shell skeletons record information about the animal and its environmental conditions throughout its life cycle. Shell material can be used to infer past ocean temperatures, seasonal fluctuations, and growth rates. Shell testing can reveal presence of trace elements and pesticides, allowing detection and identification of marine contamination and pollution.

In addition to their use in documenting what lived where and when, mollusks are important in other ways. Shells bring us joy when we find them on the beach. And many of us eat them. In 2016, three of the top 10 most valuable fisheries in the US, worth hundreds of millions of dollars, were mollusks: scallops, clams, and oysters.

Timothy A. Pearce, PhD, is the head of the mollusks section at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Mesozoic Monthly: Aspidorhynchus

As we all seek out responsible ways to enjoy our summer months while the world continues to respond to COVID-19, many of us are embracing the therapeutic effects of the great outdoors. One popular activity, especially in and around the Three Rivers, is fishing. Some modern fishes look positively primeval, as if they were hooked straight out of the Age of Dinosaurs and reeled into the present day. For July’s edition of Mesozoic Monthly, our star is Aspidorhynchus, one of the weird and wonderful fishes that inhabited the oceans of the Mesozoic Era.

Let’s start with a quick lesson on fish, for context. There are two main groups of bony fishes. One group, the class Sarcopterygii, are called the lobe-finned fishes because they have fleshy, limb-like fins that they use to paddle through the water like oars. The first vertebrates to go on land were sarcopterygians, and the descendants of these adventurous fish eventually evolved into amphibians, reptiles, and mammals – including us! Despite their prolific limbed descendants, sarcopterygians make up only a small fraction of fishes today. The vast majority of fish belong to the other class: Actinopterygii, or the ray-finned fishes. These fishes have delicate ray-like bones supporting thinly webbed fins instead of the meaty fins of the sarcopterygians. Actinopterygians are so successful that they dominate both freshwater and saltwater ecosystems, thrive in a variety of habitats, and fill various ecological niches. Such diverse lifestyles mean that actinopterygians come in many shapes and sizes. Nemo (a clownfish) is an actinopterygian. So is the barracuda that ate his mother, the catfish in the Monongahela River, and the unfortunate goldfish you won at the carnival as a kid. Most fossil fishes, like Aspidorhynchus for example, are also actinopterygians.

Aspidorhynchus is an extinct member of the order Holostei, nested, in diagrams of relatedness, within the class Actinopterygii. The only members of the Holostei today are gars and bowfins. Superficially, Aspidorhynchus looks like a gar, but it is more closely related to bowfins. Its name means “shield snout,” in reference to its pointy, swordfish-like upper jaw. Unlike swordfish, which lack teeth as adults, this snout was filled with many sharp teeth. The limited flexibility of its skull restricted its diet to tiny fish, two inches (5 centimeters) in diameter at the largest. Aspidorhynchus was not very large itself, its slender body only growing to approximately two feet (60 centimeters) in length. It was covered with ganoid scales, which are hard, diamond-shaped scales made with a shiny compound called ganoin. Only a few types of modern fishes have ganoid scales, including gar, sturgeon, and paddlefish.

Jurassic feeding frenzy: the pterosaur (flying reptile) *Rhamphorhynchus* and the predatory fish *Aspidorhynchus* attack a school of smaller fish. Usually, the baitfish were the only casualties here, but once in a while, everybody lost (see below!). Art by RavePaleoArt on DeviantArt, reproduced with permission.

Although species of Aspidorhynchus lived in the Jurassic and Cretaceous periods, we know that it encountered the same struggles as some modern fish due to several remarkable fossils. Just like swordfish, the pointy snout of Aspidorhynchus frequently got it into trouble by impaling other animals! The abundance of fossil evidence for this was provided by the unique conditions of the habitat preserved in the famous Solnhofen Limestone of Germany. In the Late Jurassic, this area was an isolated series of lagoons that accumulated a bottom layer of anoxic brine, which is extra-salty, low-oxygen water where oxygen-dependent (aerobic) life cannot survive. Despite this, the surface still teemed with life: fishes and marine reptiles dominated the water, small non-avian dinosaurs scurried along the shore, and pterosaurs (flying reptiles) and archaic birds flew overhead. The fish-eating pterosaur Rhamphorhynchus seems to have been a fairly frequent victim of the snout of Aspidorhynchus, with multiple fossils documenting unfortunate collisions in which the fish’s snout pierced and became entangled in the wing membrane of the pterosaur. (For a summary of pterosaur wings, check out the March edition of Mesozoic Monthly, on Nemicolopterus.) It’s obvious from the size of the animals that neither was trying to eat the other, but somehow, they became stuck together. As the two animals struggled to survive, they slowly drifted downward into the anoxic brine, where they suffocated and settled onto the bottom of the lagoon. If any other animals had tried to eat or otherwise disturb the corpses, they would have died in the brine as well, so the fossils of the Solnhofen Limestone are typically pristine and undisturbed by scavengers.

Three views of the most famous (and probably the most beautiful) *Aspidorhynchus* vs. *Rhamphorhynchus* fossil from the Upper Jurassic Solnhofen Limestone of southern Germany. Avid fisherman Matt Lamanna, the head of Vertebrate Paleontology at Carnegie Museum of Natural History (CMNH), jokes that the *Aspidorhynchus* looks angry, as if it’s mad about getting its snout stuck in the *Rhamphorhynchus* and dooming them both. Sorry Matt, this is just a quirk of preservation – the compression of the *Aspidorhynchus* skull during fossilization gave it the appearance of having grouchy eyebrows that weren’t there in life. You can learn more about this specimen in a paper by Frey and Tischlinger (2012).And if you want to see real fossils of both of these animals in person (albeit preserved separately), come visit the Solnhofen case in CMNH’s *Dinosaurs in Their Time* exhibition.

Because Aspidorhynchus lived only during the Mesozoic, there’s no chance that a modern-day angler will ever hook one. But should you find yourself fishing in one of Pennsylvania’s rivers or lakes this summer, and manage to land a gar or bowfin, pause for a moment and reflect on the ancient legacy of these fishes – a heritage that dates to the Age of Dinosaurs.

Lindsay Kastroll is a volunteer and paleontology student working in the Section of Vertebrate Paleontology at Carnegie Museum of Natural History. Museum staff, volunteers, and interns are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

The Bromacker Fossil Project Part VIII: Martensius bromackerensis, Honoring a colleague

Adult, holotype specimen of *Martensius bromackerensis*. Image digitally assembled by the author from five photographs taken by Diane Scott (Preparator at University of Toronto Mississauga [UTM]), 2010–2013. The specimen was collected in several large blocks.

The formal publication of some of the Bromacker discoveries took more time to complete than others, and our most recently pubished fossil, Martensius bromackerensis, holds the record in that regard. Four nearly complete specimens of Martensius were collected from the Bromacker quarry between 1995–2006. The first, discovered by Thomas Martens and his father Max, came from a jumbled pocket of fossils. Unfortunately, muddy groundwater had penetrated cracks in the subsurface of this portion of the quarry and coated and eroded bone present along these cracks. Despite this damage and the lack of a skull, we could identify the specimen as a caseid synapsid (synapsids, also known as mammal-like reptiles, are a group of amniotes whose later-occurring members gave rise to mammals).

Drawing of 1995 *Martensius bromackerensis* specimen. Because the specimen was collected in numerous pieces of rock, with parts of some bones exposed on apposing rocks, Scientific Illustrator Kevin Dupuis (UTM) had to first draw the bones exposed on each piece and then assemble all of the drawings digitally. Dotted lines indicate bone impression in the rock. Arrows point to healing scars from two fractures in the last right rib. Additional healing scars can be seen in preceding ribs. This animal apparently survived a serious injury. Modified from Berman et al., 2020.

The next specimen was discovered in 1999 by Georg Sommers (Preparator, Museum der Natur, Gotha), who prepared the fossil. It consists of a vertebral column, ribs, some limb bones, and a few scattered skull elements. Unfortunately, a more complete skull was needed to allow for comparison to other caseids, some of which are based only on skull material. It wasn’t until the discovery of two more specimens in 2004 and 2006 by Stuart Sumida and Dave Berman, respectively, that the long sought-after skull was found. Preparation of these specimens took a long time due to their size and the considerable amount of rock covering the bones in some of the blocks. My promotion to Collection Manager in 2005 left me with considerably less time to prepare fossils. Other preparators were asked to help with the preparation at both Carnegie Museum of Natural History (CMNH, Dan Pickering and Tyler Schlotterbeck) and in Dr. Robert Reisz’s lab at the University of Toronto at Mississauga (Diane Scott and Nicola Wong Ken). Robert was originally slated to lead the study, but other commitments prevented him from working on it, so Dave took over.

Besides preparation, the scientific study and publication of the specimens required illustrations and photographs, most of which were done by Diane, Nicola, and Kevin. Andrew McAfee (Scientific Illustrator, CMNH) made skeletal and flesh reconstructions of the animal, as well as an illustration of two Martensius in their ancient habitat (see The Bromacker Fossil Project Part III for a link to this illustration). All of this effort was worth it, however, because besides adding to the diversity of the Bromacker vertebrate fauna, Martensius has an unusual life history.

Juvenile specimen of *Martensius bromackerensis*. Image digitally assembled by the author from two photographs (skull and body) taken by Diane Scott in 2013. The skull, shown in ventral aspect, is incomplete and eroded on its dorsal surface.

Caseid synapsids are a diverse, long-lived group known from the Late Pennsylvanian–Middle Permian epochs (~300–259 million years ago) of Europe, Russia, and the USA, and, with one exception, all are adapted to eating plants (herbivorous). The most advanced caseids (such as the enormous Cotylorhynchus romeri) have ridiculously small skulls when compared to those of carnivores, spatulate (spoon-shaped) teeth tipped with small tubercles (cuspules) for cropping vegetation, and huge, barrel-shaped ribcages to support a large gut for fermenting cellulose-rich plants. The exception is the earliest known (Late Pennsylvanian epoch, ~300 million years ago) caseid, Eocasea martini, represented by a single, incomplete juvenile specimen from Kansas. The teeth of Eocasea are small and conical, which indicate that it most likely ate insects. Because it’s skull and ribcage are of normal size, in contrast to juveniles of Martenius, Eocasea probably ate insects throughout its life.

Reconstruction of the skull of *Martensius bromackerensis* (left) from the Early Permian (~290 million years ago) Bromacker quarry, Germany, and the more advanced caseid Ennatosaurus tecton (skull, middle and skull fragment with cuspule-tipped teeth, right), from the Middle Permian (~263 million years ago) of Russia. Skull reconstruction of *Martensius* made by Diane Scott and modified from Berman et al., 2020. Ennatosaurus skull reconstruction and jaw fragment drawing modified from Maddin et al., 2008.

Martensius has a modestly expanded ribcage and a small skull, suggesting that it was herbivorous. Furthermore, the feet of Martensius, like those of other caseids in which the feet are known, are large, with massive, elongated, strongly recurved claws. Martensius also has a well-supported hip region that may have enabled it to rise on its hind legs to reach and tear down overhead branches to feed upon.

The upper and lower teeth of the adult Martensius differ from those of more advanced caseids in being triangular and lacking cuspules. The upper jaw teeth of the juvenile resemble those of the adult, but the lower jaw teeth are more numerous—31 in the juvenile compared to 25 in the adult—and surprisingly, they resemble those of Eocasea. Dave concluded that juveniles of Martensius had teeth adapted for eating insects, which were replaced by an adult dentition that would’ve been good for cropping plants and piercing insects. Remarkably, the juvenile Martensius apparently died while in the process of replacing its juvenile dentition with that of adults.

So why have different juvenile and adult dentitions? Modern animals that eat fibrous plant matter have micro-organisms called fermentative endosymbionts in their large guts, which break down difficult-to-digest plant matter via fermentation. It is assumed that early fossil plant-eaters with broad ribcages also had large guts housing fermentative endosymbionts. Prior to the discovery of Martensius, other scientists hypothesized that early herbivores acquired endosymbionts by eating herbivorous insects that already had these microbes in their guts. In Martensius, the introduction of endosymbionts apparently occurred during the juvenile, insectivorous stage of life, which set the stage for adults to add plants to their diet.

Flesh (top) and skeletal (bottom) reconstructions of *Martensius bromackerensis*. Illustrations by Andrew McAfee and modified from Berman et al., 2020.

The generic name Martensius honors Thomas Martens for his discovery of vertebrate fossils at the Bromacker quarry and his perseverance in maintaining a highly successful, long-term field operation resulting in the discovery and publication of the exceptionally preserved Bromacker fossils. Bromackerensis refers to the Bromacker quarry, the only locality from which this species is known.

Stay tuned for my next post, which will feature some terrestrial dissorophoid amphibians.

For those of you who would like to learn more about Martensius, here’s a link to the 2020 Annals of Carnegie Museum publication in which it was described.

Amy Henrici is Collection Manager in the Section of Vertebrate Paleontology at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

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July 29, 2020 by wpengine

Collected on this Day in 1966: Santa Clauses

Christmas in July…”Santa Claus” floating in the air.

(Or I guess, technically Boxing Day in July, if that’s a thing.)

thistle seed fluff "Santa Claus" in hand

Make a wish!

Have you ever seen fluff floating by in the air, especially in late July, early August? Kids love chasing the fluff around, often referring to them as “Santas” or “Santa Clauses.” You catch it, make a wish, and let them go again, floating away.

dried thistle specimen on herbarium sheet

These are seeds! Most likely thistle seeds, like this specimen here. Or other seeds that have similar “fluff”-like structures. The botanical term for this “fluff” is pappus. Pappus is a modified part of flowers in many species in the sunflower family, Asteraceae (think dandelion). These structures help the seed disperse in the wind, floating away in the breeze, carrying the seed far away. If you’ve tried to catch them, you know they float away in the air very easily. The seeds are small, and often times have already disconnected from the pappus when you catch them.

Check out the “Santa Claus” pappus on this specimen of bull thistle (Cirsium vulgare), collected on July 26, 1966 by Leroy Henry near Woodbine (Butler county), Pennsylvania. Leroy Henry was a botany curator at the Carnegie Museum. All species in the genus Cirsium are known as “thistles.” They have distinctive spiny leaves and stems, with even more distinctive purple flower heads. There are native thistles, but many are introduced. Thistles are common in disturbed areas, and in and around agricultural fields across the country. Bull thistle is native in Europe and Western Asia, but widely introduced across the world, including North America. It is the national flower of Scotland, but the species is considered invasive in many places.

Keep an eye out for thistles, and “Santa Clauses.” Don’t forget to make a wish.

Find this bull thistle specimens here.

Check back for more! Botanists at the Carnegie Museum of Natural History share digital specimens from the herbarium on dates they were collected. They are in the midst of a three-year project to digitize nearly 190,000 plant specimens collected in the region, making images and other data publicly available online. This effort is part of the Mid-Atlantic Megalopolis Project (mamdigitization.org), a network of thirteen herbaria spanning the densely populated urban corridor from Washington, D.C. to New York City to achieve a greater understanding of our urban areas, including the unique industrial and environmental history of the greater Pittsburgh region. This project is made possible by the National Science Foundation under grant no. 1801022.

Mason Heberling is Assistant Curator of Botany at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

The Bromacker Fossil Project Part VII: Eudibamus cursoris, the Original Two-legged Runner

New to this series? Read The Bromacker Fossil Project Part I, Part II, Part III, Part IV, Part V, and Part VI.

Holotype specimen of *Eudibamus cursoris*, the most complete bolosaurid reptile known. Photo by the author, 2013.

Stuart Sumida discovered some small bones in the Bromacker quarry in 1993, the same year that the holotype skeleton of Diadectes absitus was found. Dave Berman told me that when Stuart showed them to him, he couldn’t see anything because they were so small. Upon closer examination, Dave, Stuart, and Thomas Martens identified them as those of the captorhinomorph reptile Thuringothyris mahlendorffae. Thomas’ wife Stefani, whose maiden name is Mahlendorff, discovered the first specimen in the Bromacker in 1982, and Thomas and a colleague named it in her honor in a 1991 publication.

The fossil was exposed in several pieces of rock, which Thomas shipped to Carnegie Museum of Natural History (CMNH) along with the large block of rock containing Diadectes. I didn’t prepare the specimen until several years later, as other projects, including the Diadectes, overshadowed it. Once I began working on it, though, Dave and I realized that it was not Thuringothyris. Indeed, we had no idea what type of animal it was, and our puzzlement grew as I exposed more of it. The identity wasn’t revealed until I had uncovered some very unusual, tiny teeth, which under the high magnification of the preparation microscope appeared to have a bulbous cusp towering over a basin. They looked vaguely familiar to me, but because I couldn’t immediately put a name on them, I rushed to get Dave from his office. Once Dave saw the teeth, he realized that the specimen was a new genus and species in the rare, enigmatic reptile group Bolosauridae.

Tiny teeth of a bolosaurid reptile, *Bolosaurus striatus*, in lateral (side; left) and occlusal (chewing surface; right) views. The specimen is in the CMNH Vertebrate Paleontology collection. Photos by Spencer Lucas (Research Associate, CMNH).

Until the discovery of Eudibamus cursoris, bolosaurids were represented in the fossil record by two genera, Bolosaurus and Belebey, which were based mainly on poorly preserved skull and fragmentary jaw fossils from Texas and Russia, respectively. Even though bolosaurids had been known since 1878, their relationship to other reptiles was not well understood. The nearly complete anatomy of Eudibamus allowed our team to determine that bolosaurids are the oldest member of the ancient group of reptiles called Parareptilia. This group has no living relatives, except possibly for turtles, a hypothesis that is highly debated by scientists.

Eudibamus cursoris fossil — Closeup of front and hind legs of *Eudibamus*. The hind leg, folded upon itself, is considerably longer than the front leg. Photo by the author, 2013.

When our study of the fossil began, we realized that Eudibamus was very different than other reptiles from that time. Proportions of the limbs and positions of the articulation surfaces on the upper and lower hind leg bones indicated that, in terms of posture, Eudibamus resembled a bow-legged human with a bad back instead of a typical sprawling reptile on four legs. It could stand and locomote on its hind legs in an upright posture (bipedal) with its legs held close together and in the same plane (parasagittal).

Dave was in constant phone communication with team member Dr. Robert Reisz (Professor, University of Toronto at Mississauga). One day Robert called Dave to ask if all the tail had been exposed, because he learned that modern lizards that are able to run bipedally have a long tail to help maintain their balance. The specimen was in Dave’s office and he immediately uncovered more of the tail and then let me finish the task. The tail was indeed very long and extended close to the edge of the block, which I had previously reduced in size. Additionally, we determined that the third, fourth, and fifth toes of the hind foot also were greatly elongated through lengthening of some of the individual toe bones, and that the first and second toes were extremely shortened by the reduction in size of individual toe bones. We hypothesized that when Eudibamus ran bipedally, it would rise on its toes, so that only the tips of the third, fourth, and fifth toes would contact the ground.

Drawing of the hind leg of *Eudibamus cursoris* (left) and the roughly contemporaneous reptile *Captorhinus* (right). Leg drawings are scaled to the same torso length of the whole animal. Illustrations of the animals are not to scale. Hind leg drawings are modified from Berman et al., 2000 and animal illustrations are from Wikimedia Commons.

Eudibamus occurred at least 60 million years before other bipedal, parasagittally-running reptiles appeared in the fossil record. This is reflected in its scientific name, which is derived from the Greek “eu,” meaning original or primitive, and “dibamos,” meaning on two legs. “Cursoris” is Latin, meaning runner. Examples of other reptiles using this locomotion mode are the dinosaurs Allosaurus fragilis and Tyrannosaurus rex, which you can view in CMNH’s Dinosaurs in Their Time exhibition.

So, what was the advantage of being able to run bipedally instead of running on all four legs? Lengthening the hind leg and foot would greatly increase stride length, especially if only the tips of the toes contacted the ground, which is an efficient way to increase speed. Eliminating arm to ground contact while running removes forelimbs from the path of the long-striding hind legs. The bulbous teeth and jaw structure of Eudibamusindicate that it was herbivorous. It seems likely, then, that Eudibamus used its ability to sprint to avoid becoming a tasty meal for a pursuing predator.

Eudibamus cursoris illustration — Peter Mildner (exhibit preparator at the Museum der Natur, Gotha) made a surprise visit to the Bromacker one afternoon to show us a model of *Eudibamus cursoris* he’d made. This image shows the model in the present day Bromacker quarry, part of the region it inhabited 290 million years ago. Photo by the author, 2006.

One of our laments is that a fossil trackway preserving Eudibamus walking quadrupedally and then switching to a bipedal gait has yet to be found.

Next time you are at CMNH, make sure you see the cast of the fossil skeleton and a model of Eudibamus that are exhibited in the Fossil Frontiers display case in CMNH’s Dinosaurs in Their Time exhibition. Stay tuned for my next post, which will feature the herbivorous mammal-like reptile Martensius bromackerensis.

For those of you who would like to learn more about Eudibamus, here is a link to the 2000 Science publication in which it was described: https://science.sciencemag.org/content/290/5493/969.

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The Bromacker Fossil Project Part VIII: Martensius bromackerensis, Honoring a Colleague

Meet Ainsley Seago, New Associate Curator of Invertebrate Zoology

Abstract of recent research (bearing in mind that I have a very loose grasp on what 8th graders are up to these days)

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