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MESOZOIC MONTHLY: Volaticotherium

by Lindsay Kastroll

Once again, spring has sprung. Prepare to see the gorgeous forests of Pennsylvania launch back into action. I, for one, can’t wait to get outside and explore as the weather continues to improve. I was recently reminded of the fact that Pennsylvania is home to two species of flying squirrels, and I am definitely adding them to my list of things to see. But of course, this is Mesozoic Monthly, so flying squirrels can’t be the stars of this article. Instead, the superficially flying squirrel-like “ancient gliding beast” Volaticotherium antiquum is stealing the spotlight!

Although Volaticotherium was about the size of a modern flying squirrel at 5–6 inches (13–15 cm) long, it belonged to a group of early mammals called eutriconodonts that includes some of the largest mammals that lived alongside non-avian dinosaurs. “Eutriconodont” means “true three-coned tooth,” in reference to the three longitudinally aligned cusps on their molars. Although not all mammals today have three-cusped molars, the ancestors of modern mammals did. Does this mean that modern mammals evolved from a eutriconodont? The answer is no, though they did evolve from a mammal with eutriconodont-like teeth.

We can split modern mammals into two main groups: the monotremes, which are egg-laying mammals like the platypus, and the therians, which include both marsupial and placental mammals (like kangaroos or humans, respectively). The ancestors of monotremes diverged (meaning, formed their own ‘branch’ of the evolutionary tree) before eutriconodonts and therians evolved. Eutriconodonts and therians share a different, more recent, and as-yet unknown common ancestor. Monotremes, therians, and eutriconodonts actually lived alongside one another for over one hundred million years before eutriconodonts became extinct near the end of the Cretaceous Period (the third and final division in the Mesozoic Era, or ‘Age of Dinosaurs’).

 

This flowchart represents a simplified phylogeny (aka, evolutionary tree) of the relationships discussed in the previous paragraph. A lot of ‘branches’ and intermediate steps are missing from this phylogeny to make it easier to follow.

The canines and molars of eutriconodonts were pointy, suggesting that these mammals were carnivores or insectivores. Volaticotherium is no exception, which makes it particularly unique, as most other gliding mammals are herbivores! Because it was so small, Volaticotherium was probably an insectivore, but a larger cousin, Jugulator, could probably eat small vertebrates. As an arboreal glider, Volaticotherium could soar from tree to tree to catch insects in midair. Instead of wings, it had a patagium, a broad flap of skin that stretched between the fore- and hind limbs, creating enough surface area to achieve gliding descents. The various limb adaptations necessary to make Volaticotherium an efficient glider also made it poor at maneuvering on the ground. It can be hard to understand why an animal would evolve features that would hinder its terrestrial movement, and multiple hypotheses have been put forth to try to explain this. Most of these focus on the benefits of leaping out of trees to escape predators or to quickly traverse territory between arboreal food sources, scenarios based on herbivorous mammals. Because Volaticotherium was a gliding predator, perhaps gliding conferred other advantages to this eutriconodont.

Restoration of Volaticotherium in mid-glide by Jose Antonio Peñas, used with permission. Take note of those sharp canine teeth, useful for catching tasty insects! You can find more of Peñas’ art on their DeviantArt, ArtStation, or YouTube.

The fossilized remains of Volaticotherium were found in a layer of rock called the Daohugou Bed in China. This deposit consists of lakebed sediment and volcanic ash compacted into solid rock over millions of years as more heavy sediment was deposited on top of it. There is a debate about how old the Daohugou Bed is, but most estimates place it near the middle or end of the Jurassic Period (the middle period of the Mesozoic). Getting the timing right is important. Because Volaticotherium is among the oldest known gliding mammals, its discovery pushes the origin of mammalian gliding back as much as 70 million years earlier than previously thought!

A variety of factors have led geologists to struggle in determining the age of the Daohugou Bed. In an ideal geologic record, rock layers would be perfectly horizontal, creating a continuous stack with the oldest layers on the bottom and the newest layers on top. However, this is rarely the case. Sediment may be eroded before new layers are deposited, creating a gap of time without record in that sequence of rocks. This phenomenon, where two rock layers do not represent a continuous progression of time and have a gap of data missing between them, is called an unconformity. Other issues with dating rock layers involve the squeezing, stretching, folding, melting, and chemical alteration of rock layers when they’re subjected to geologic processes. These forces can result in old rock layers being placed on top of younger ones, making it hard to determine the actual sequential order of the rocks. Changes can also occur within the minerals that compose the rocks, making radiometric dating much more difficult.

The Daohugou Bed has an unconformity above and below it, and it has been folded, which makes attributing an exact age to it that much harder. When you go out hiking in the beautiful spring weather on the horizon, take a moment to look at the rock outcrops you pass and think about what those layers might have experienced on their journey to where they are today. And if you continue your hike after sunset, be sure to keep your eyes peeled. If you’re lucky, you might just catch a glimpse of a flying squirrel gliding through the forest!

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.

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Carnegie Museum of Natural History Blog Citation Information

Blog author: Kastroll, Lindsay
Publication date: March 31, 2021

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Carnegie Museum of Natural History Adds Five New Specimens to Cretaceous Seaway Display

New specimens include world’s only juvenile skeleton of plesiosaur Libonectes
 
Enhancements made possible with support from The Elijah Straw Memorial Fund 

The massive Manitoba pliosaur closes in on its potential prey, a juvenile of the plesiosaur Libonectes morgani. Photo: Tim Evans, Carnegie Museum of Natural History.

Visitors at Carnegie Museum of Natural History may now view five impressive new specimens in the Cretaceous Seaway display of its flagship exhibition Dinosaurs in Their Time. The specimens include a newly restored Tylosaurus mosasaur fossil skull and four replica skeletons (a pliosaur, a plesiosaur, and two fishes) created by Triebold Paleontology, Inc. The freshly updated gallery is now on view. 
 
“Our new Cretaceous Seaway displays put visitors smack dab in the middle of a life-and-death struggle taking place in midwestern North America some 92 million years ago,” says Matt Lamanna, Carnegie Museum of Natural History’s Daniel G. and Carole L. Kamin Co-Interim Director and Mary R. Dawson Associate Curator of Vertebrate Paleontology. “Collectively, our new Seaway beasts tell the story of evolution and extinction in an ancient ocean over the span of more than 30 million years. And they remind us that no species—not even humans—is immune to extinction.”
 
The juvenile plesiosaur Libonectes is the only one of its kind, replica or otherwise, on display anywhere in the world. Lamanna and Triebold Paleontology, Inc. worked closely together to create the specimen. “Nobody’s ever found a baby Libonectes before, so to produce one, the gang at Triebold Paleontology and I had to digitally alter a virtual 3D model of an adult skull and then digitally sculpt other bones using photos of Libonectes skeletons and those of related plesiosaurs,” says Lamanna. “When all the computer work was done, the 3D models were then printed to yield the physical replica. The whole process really opened my eyes to the possibilities of 3D scanning, modeling, and printing in paleontology.”

Another of the newly-added specimens, the large Cretaceous predatory fish Enchodus petrosus. Photo: Calder Dudgeon, Carnegie Museum of Natural History.

The new specimens are made possible with support from The Elijah Straw Memorial Fund. According to Tom Straw, Elijah’s father, the natural history museum was a special place for Elijah, and one particular display captured his imagination.  
 
“When Elijah was five years old, he fell in love with the skull cast of Dunkleosteus terrelli, a prehistoric fish,” said Straw. “When that went off view, Elijah was very concerned. I wrote to Dr. Matt Lamanna to ask what was going on,” said Straw, who was surprised when Lamanna responded by inviting them in to see the specimen in the museum’s behind-the-scenes area.
 
That tour, which also included a glimpse of the world’s first T. rex fossil, led to a lasting friendship with the Carnegie Museums.
 
When Lamanna learned of Elijah’s death a year later, he put a plan in motion to honor the little boy and his love of prehistoric life. A few months later, he contacted the family to let them know that the museum had dedicated the Dunkleosteus terrelli cast, now back on display in the museum, to Elijah.
 
The Elijah Straw Memorial Fund has since supported numerous improvements in the Cretaceous Seaway, including lighting, engineering and installation of four new replica skeletons, and the unveiling and display of a real fossil skull of the giant marine reptile Tylosaurus to honor Elijah’s memory. The Tylosaurus fossil skull, collected over a century ago, was newly restored by fossil preparator Dan Pickering, returning the specimen to display after many years stored behind the scenes. Tylosaurus is a member of the mosasaur group, which became famous in recent years for oversized “starring roles” in two Jurassic World movies. The Cretaceous Seaway enhancements were also made possible thanks to the generous support of Dr. Richard W. Moriarty.

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Mesozoic Monthly: Dreadnoughtus

Last January, we started out hopeful for 2020, but unfortunately it ended up being a very difficult year for almost everyone. After an equally challenging start to 2021, I think it is safe to say our attitudes toward this year are more guarded, but nonetheless brave. We know that more hard times might be approaching, but if we could make it through 2020, we can make it through its successor. It is in this spirit that this edition of Mesozoic Monthly features Dreadnoughtus schrani, a colossal sauropod dinosaur whose genus name literally means “fearer of nothing.”

Dreadnoughtus has many connections to Carnegie Museum of Natural History (CMNH). Starting in 2005, a team that included CMNH’s own Dr. Matt Lamanna collected the only known fossil skeletons of the ginormous species in Santa Cruz Province of southern Patagonia, Argentina. Matt was also one of the authors of the paper that officially named the beast in 2014. Furthermore, many of the bones were scientifically prepared by staff and volunteers in the museum’s on-exhibit fossil lab, PaleoLab. Preparation involves freeing the fossils from the rock in which they were preserved (called matrix) using special tools, and then gluing/reinforcing the fossils back together as needed. Next time you visit CMNH, make sure to take a peek in PaleoLab to see our preparators in action!

CMNH Scientific Preparator Dan Pickering carefully removes rock from a gigantic cervical vertebra (neck bone) of Dreadnoughtus, ca. 2012. The top of the vertebra is projecting toward the viewer; the front is toward the left of the image. Photo courtesy Matt Lamanna.

Sauropod dinosaurs such as Dreadnoughtus are easily recognized by their frequently huge size, long necks, and long tails. CMNH’s Dinosaurs in Their Time (DITT) exhibition features real fossil skeletons of three different sauropods: Camarasaurus, Apatosaurus, and Diplodocus. Brachiosaurus, one of the stars of Jurassic Park, is also a sauropod, and is featured in the mural in the Jurassic Period atrium in DITT.

Dreadnoughtus belongs to a group of sauropods called titanosaurs that lived during the following Cretaceous Period, largely in the Southern Hemisphere. Titanosaurs have many interesting features that make them unique, such as simplified front feet with very few bones, extra-wide shoulders and hips, and even (in some species) bony plates called osteoderms embedded in the skin. However, as their name implies, titanosaurs’ primary claim to fame is their generally titanic size. Many titanosaurs were absolutely enormous – the smallest members of the group, such as Magyarosaurus, were outliers likely produced by insular dwarfism, a phenomenon in which typically large-bodied animals evolve smaller sizes that are more sustainable in geographically restricted habitats such as islands. Magyarosaurus lived in what’s now the Transylvania region of Romania, which was part of an island at the end of the Cretaceous. In contrast, Dreadnoughtus, which lived in prehistoric South America, was not restricted by an island habitat, and grew to an estimated 85 feet (26 meters) long. And, based on studies of the microscopic internal structure of its bones, it’s possible that the already-immense name-bearing specimen wasn’t even done growing before it died!

When you’re 85 feet long from head to tail, you tend to dwarf everything around you! I bet you didn’t even notice the two 13-foot-long Talenkauen santacrucensis at the bottom right – ornithischian dinosaurs that lived alongside Dreadnoughtus in the ~75-million-year-old ecosystem of southern Argentina’s Cerro Fortaleza Formation. This digital painting of Dreadnoughtus and company is by artist Charles Nye, used with permission. You can find more of his art under the name @thepaintpaddock on Instagram and Twitter!

As you can imagine, it’s very hard to determine how much a dinosaur would have weighed when it was alive, especially for a dinosaur as large as Dreadnoughtus! Although multiple methods for calculating the weight of an extinct animal have been proposed, one of the most commonly employed techniques is volumetric mass estimation. Paleontologists using this method work with typically incomplete skeletons to first estimate how much of each type of tissue (like muscle or fat) covered the skeleton; afterward, they calculate how much each tissue type (including bone) weighed. It’s a difficult, somewhat speculative process that can result in different researchers producing wildly different estimates for the same animal’s weight. Estimates for Dreadnoughtushave been anywhere between 24.4 and 65.4 US tons (22.1 and 59.3 metric tons), but the most recent estimate was 54.0 US tons (49 metric tons). For comparison, a typical school bus weighs around 12.5 US tons (11.3 metric tons)! Clearly, no matter how you estimate it, Dreadnoughtus was a massive animal.

It’s notoriously hard to find complete sauropod skeletons – because their bodies and bones were so large, they tended to break apart and to be at least partially destroyed before they could be buried and preserved. The holotype, or name-bearing, specimen of Dreadnoughtus is among the most complete giant titanosaur skeletons ever found. This reconstruction by scientific illustrator Lindsay Wright (a former volunteer here at CMNH) shows which bones of this titanosaur have been discovered (in white).

Gargantuan size has its drawbacks, but it also brings enormous benefits. It takes an absurd amount of resources to grow this large and power the organs needed to support life. However, if enough food is present to sustain this growth, predators are no longer an issue. Not even the largest meat-eating dinosaurs could pose a threat to something as large as an adult Dreadnoughtus. The only chances predators had to taste this sauropod were to hunt it when it was a small juvenile or to scavenge it when it was dead or dying. That seems to be what happened, too, because teeth of carnivorous dinosaurs were found scattered around the fossils.

So, as we continue our journey through 2021, let us think of ourselves like the unassailable Dreadnoughtus: the challenges of 2020 helped us to grow tremendously resilient, and the trials coming our way will not fracture our resolve. Times may be hard, but we are gigantic dinosaurs with no natural predators. We can do this.

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.

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Mesozoic Monthly: Vegavis

Disclaimer: Our dinosaur paleontologist Matt Lamanna typically edits Lindsay Kastroll’s Mesozoic Monthly posts before they go live, but due to some much-needed holiday revelry he was late in getting to this one. As such, it’s being posted in January rather than in December as Lindsay had intended. Matt sends his apologies!

‘Tis the season for eating candy canes, singing Christmas carols, and kicking off a new year of Mesozoic Monthly! That’s right – one year ago, the first Mesozoic Monthly debuted in December 2019, spotlighting the ceratopsian dinosaur with a candy cane-shaped nasal horn, Einiosaurus. This December, we’ll move from candy canes to carols as we feature Vegavis iaai, the first Mesozoic bird known to have had a syrinx (the avian “voice box”)!

Photo (left) and computed tomographic (CT) scan image (right) of the type, or name-bearing, specimen of Vegavis iaai, a partial skeleton inside a ~70-million-year-old rock concretion from Vega Island, Antarctica. Photo from the Antarctic Peninsula Paleontology Project website.

Birds evolved during the Mesozoic Era, the so-called “Age of Dinosaurs,” before non-avian dinosaurs became extinct. Last month, for the November edition of Mesozoic Monthly, we discussed what makes modern birds members of the group of theropod dinosaurs, but what I didn’t mention is that birds lived alongside non-avian dinosaurs! Birds evolved around 165 to 150 million years ago during the Jurassic Period, the second of three time periods in the Mesozoic. The Jurassic dinosaur Archaeopteryx represents a transitional stage between birds and non-avian dinosaurs: its fossils display obvious flight feathers like a bird, but it also has many non-avian dinosaur characteristics such as a toothy mouth, a long bony tail, and even a miniature version of a killing claw like that of Velociraptor.

Replica skeleton of Archaeopteryx lithographica on display here at CMNH. Photo from Wikimedia Commons.

Birds lived and evolved alongside their non-avian relatives for almost 100 million years, and by the end of the Cretaceous Period (the third and final time period of the Mesozoic), the distinct groups of birds that we recognize today were beginning to originate. Vegavis was an ancient relative of ducks and geese discovered on Vega Island, an island off the coast of the Antarctic Peninsula (the part of Antarctica that juts northward towards South America). At that time, Antarctica was warmer than it is now and home to lush temperate forests.

Sandwich Bluff, the site on Vega Island, Antarctica that has produced all known fossils of Vegavis. Photo by Eric Roberts, James Cook University.

With many skeletal features suggesting that it was a diving bird that propelled itself with its feet, Vegavis was probably as well-adapted to life in the water as it was to life in the skies. While it’s certainly incredible that scientists are able to deduce this much information about its behavior from just its skeleton, the story gets better: one specimen of Vegavis includes a fossilized syrinx, the organ that birds use to produce sound! A syrinx’s shape is directly related to the sounds it can make, and the fossilized syrinx of Vegavis was a distinctively goose-like asymmetrical shape. So, this ancient bird may well have honked! If it did, it would have sounded much more like six geese-a-laying than, say, four calling birds, three French hens, two turtle doves, or a partridge in a pear tree.

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.

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The Bromacker Fossil Project XIII: What We Learned

Pebble or Jaw?

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The Bromacker Fossil Project Part XIII: What We Learned

New to this series? Need to catch up on your reading? Here are all the previous posts for the Bromacker Fossil Project: Part I, Part II, Part III, Part IV, Part V, Part VI, Part VII, Part VIII, Part IX, Part X, Part XI, and Part XII. 

Collage of the fossils highlighted in this series. Images not to scale. Photos by the author, Dave Berman, and Thomas Martens.

The Bromacker quarry is a rare site in that it preserves exquisite, articulated fossils of a unique vertebrate fauna that lived in an atypical or rarely recorded Early Permian (~290 million years ago) setting. Early in our work at the Bromacker, we became aware that the fossil vertebrates we were finding were unknown or extremely rare in Europe but were closely related or identical to species commonly found in North America. Until then, most of the fossil vertebrates found in Europe were discovered in gray to black sediments deposited in ancient lake beds, whereas the fossils from the Bromacker quarry occurred in red beds representing a terrestrial setting. Paleontologists looking for fossils in Europe typically prospected the gray to black sediments where fossils were relatively plentiful rather than red beds, which were thought to represent arid environments not conducive to fossil preservation.

Photograph of a diorama showing the Tambach Basin 290 million years ago, which was once exhibited at the Museum der Natur, Gotha. It was built in 1996, so many of the inhabitants of the basin weren’t yet discovered. One of these is Dimetrodon teutonis, which was inadvertently depicted as being large and numerous. Image provided by Thomas Martens, 2020.

In a collaborative effort to help determine how the fossil deposit at the Bromacker quarry formed and why its vertebrate fauna is unique, Dave Berman invited his colleague David Eberth to join us for the 1998 field season. David is a geologist/vertebrate paleontologist who was then employed by the Royal Tyrrell Museum of Palaeontology in Canada but is now retired. The sediments preserving the Bromacker fossils are part of a rock unit called the Tambach Formation and were deposited in the Tambach Basin. The results of David’s study, built in part upon investigations by other geologists and paleontologists, indicate that the Tambach Basin was situated within an ancient mountain range and isolated from river systems. At the time the fossils were deposited, the basin was internally drained, and as a result, when it rained, water would flow towards the basin center and form ephemeral ponds and lakes. Based on the geology, fossil plant assemblage, and geographic setting of the Tambach Basin, David concluded that the climate was possibly similar to the wet‑and‑dry tropical climate of modern North African savannas, Brazilian Campos, or the Venezuelan Llanos.

Map showing the areal extent of the Tambach Formation today and the inferred boundary of the Tambach Basin, with arrows indicating direction of water flow. The northern boundary of the basin is not preserved, but it was thought to have been closed when the Bromacker fossil deposit formed. Modified from Eberth et al., 1997.

Most of the fossils discovered at the Bromacker quarry came from two massive units, the more fossiliferous of which is about 21 inches thick, that formed in separate major flooding events. David theorized that these deposits formed when heavy rain caused a sheet-flood of sediment‑laden water to sweep down the sides of the Tambach Basin and across the basin floor, killing any animals that couldn’t escape the flow. The sheet-flood transported the carcasses to the basin center where they were deposited, rapidly buried, and eventually fossilized. These deposits record a unique snapshot of vertebrate life in the Tambach Basin, because only animals inhabiting the basin would have been captured by the sheet-flood.

In contrast, most Early Permian fossil‑bearing deposits in North America formed on coastal or alluvial plains. Carcasses would’ve been transported to the deposition sites by rivers, some of which had a large geographic reach. These types of deposits can accumulate over a long period of time and have potential to mix together fossils from different environments.

Photograph of a diorama once exhibited at Carnegie Museum of Natural History that shows a typical Early Permian peat swamp or backwater swamp of a major river system. A similar modern environment would be the Okefenokee Swamp, Georgia. Photo by Mindy McNaugher, 2007.

Besides having an atypical geographic setting, the makeup of the Bromacker vertebrate fauna differs from those known from other Early Permian sites. The Bromacker vertebrate fauna has a low diversity of terrestrial tetrapods, but more importantly, it lacks fishes and aquatic to semi‑aquatic constituents. This is probably due to the Tambach Basin’s isolation from regional river systems and because it experienced seasonal to sub‑seasonal drying, making it difficult for water-reliant vertebrates to become established. Based on numeric counts of individual specimens, we determined that the relatively large‑sized herbivores Diadectes, Orobates, and Martensius greatly outnumbered the synapsid apex predators Dimetrodon and Tambacarnifex. We think the rarity and low diversity of synapsid carnivores is probably due to the lack of an aquatic to semi‑aquatic component in the food chain.

In contrast, most Early Permian North American localities preserve a diverse, mixed aquatic‑terrestrial fauna that either lived in water or was closely associated with water and aquatic food chains. Herbivores were rare in terms of both diversity and numbers, whereas synapsid apex predators were diverse and numerous.

A more dynamic North American Early Permian scene that includes a mixed aquatic‑terrestrial vertebrate fauna. The Dimetrodon on the right has caught a freshwater shark, demonstrating the importance of aquatic animals in the food chain. © Julius Csotonyi/Houston Museum of Natural Science.

The Bromacker is the oldest known terrestrial vertebrate ecosystem in which herbivores greatly outnumber apex carnivores, and in that respect, it resembles terrestrial vertebrate ecosystems of today. A modern example is the African savanna in which large herds of herbivores such as zebra, wildebeest, and buffalo provide a food source for a much smaller number of carnivores including lions, cheetahs, and hyaenas. Indeed, we consider the Bromacker to represent an early stage in the development of the modern terrestrial vertebrate ecosystem and that these early stages were restricted to upland areas isolated from aquatic‑based food chains.

This summary concludes the Bromacker Fossil Project blog post series. I hope that you’ve enjoyed reading it. Cast replicas of many of the fossils described in this series are exhibited in the Fossil Frontiers display case in CMNH’s Dinosaurs in Their Time exhibition, so be sure to look for them on your next visit. I’m grateful to Dave Berman, Albert Kollar, Thomas Martens, and Stuart Sumida, who answered numerous questions and provided photographs, and to Patrick McShea and Matt Lamanna for their editing skills. Click here to read the paper by Eberth et al. 2000.

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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The Bromacker Fossil Project Part XII: Tambacarnifex unguifalcatus, the Tambach executioner

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

Holotype specimen of Tambacarnifex unguifalcatus, preserved in couterparts. Photographs by Dave Berman, 2010.

Tambacarnifex unguifalcatus was discovered by Thomas Martens and his father Max in 1995 in the same pocket of fossils from which the first-discovered specimen of the herbivorous basal synapsid Martensius bromackerensis was recovered. Because numerous fossil animals were jumbled together, Thomas and Max weren’t able to collect individual specimens from the bone pocket using our standard technique of surrounding a specimen in a plaster and burlap jacket. Instead, they collected all the individual pieces of rock that contained bone or at least appeared to contain bone, as most rock pieces were coated in goopy mud. Thomas cleaned the rock pieces with water to reveal the bone, and then pieced together the various specimens.

He eventually sent us the specimen that became the holotype of Tambacarnifex, along with pieces that he thought might go with it. Dave and I spent hours piecing together the remainder of the skeleton, and we searched the collections at the Museum der Natur, Gotha for missing pieces in subsequent field seasons. The majority of the specimen was recovered, but the skull, a few vertebrae, and distal finger and toe bones are missing. A rock piece with the greater portion of a lower jaw with teeth was also collected from the bone pocket, though it couldn’t be associated with the skeleton and may represent a second individual. A lot of bone was lost from the specimen, but impressions of missing bone were preserved, which proved useful for identifying wrist and ankle bones, among others. Dave used a white pencil to color in the bone impressions so they would stand out for study and in photographs of the specimen. Ultimately, we realized that Martensius and Tambacarnifex were preserved one on top of the other, though separated by several inches of rock.

The lower jaw piece of Tambacarnifex unguifalcatus. Photograph by Dave Berman, 2008.

The teeth of Tambacarnifex preserved in the lower jaw are strongly recurved and flattened side-to-side, which, along with other features preserved in the skeleton, indicate it is a member of the basal synapsid group (family) Varanopidae and in the subfamily Varanopinae. The Varanopidae have been likened to the actively predaceous modern monitor lizards in the family Varanidae, hence the similar name. Varanopids were the most diverse and longest-surviving basal synapsids, being known from the Late Carboniferous–Middle Permian (~309–260 million years ago) of North America, Europe, Asia, and Africa. With their sharp, recurved teeth and a gracile skeleton, scientists think varanopids were agile predators, at least compared to other animals of their time. They range from about 12–78 inches in length, with the smallest ones probably being insectivorous and the larger ones carnivorous. Tambacarnifex has an estimated body size of about 35 inches, and as a medium-sized varanopid with gracile limbs it would have been an agile carnivore, preying on on any of the Bromacker vertebrates that it could catch.

An articulated but incompletely preserved series of 11 vertebrae of Tambacarnifex unguifalcatus. Notice that the neural spines are low and subrectangular, so it is unlikely that they supported a sail, as occurs in some other basal synapsids such as Dimetrodon teutonis. The front of the animal is to the left. Photo by Dave Berman, 2008.

Unlike Dimetrodon teutonis, the other apex predator at the Bromacker, Tambacarnifex has broad, low neural spines that alternate in height. It differs from other varanopines in the shape and anterior inclination of its neural spines and in having greatly elongated and recurved bony claw supports in its hands and feet. The generic name Tambacarnifex was coined in reference to its position in the food chain: “Tamba,” for the Tambach Basin, which the holotype inhabited, and the Latin “carnifex,” meaning executioner, for its role as an apex predator. “Unguifalcatus” was derived from the Latin “unguis,” nail or claw, and “falcatus,” meaning sickle-shaped, in reference to the long, strongly recurved bony claw supports.

Incomplete front (left) and hind (right) feet of Tambacarnifex unguifalcatus. Notice the extremely long bony claw supports preserved on the first, third, and fourth fingers of the front foot and the fourth toe of the hind foot. I–V refer to finger and toe numbers. Photos by Dave Berman, 2008.

Illustration of Tambacarnifex unguifalcatus consuming a Dimetrodon teutonis carcass. Outline drawing by Matt Celeskey, colored (with permission) by Carnegie Museum of Natural History Vertebrate Paleontology Scientific Illustrator Andrew McAfee.

Stay tuned for the final post of this series, which will summarize what we’ve learned about the Bromacker. Click here if you would like to download your own copy of the outline drawing of Tambacarnifex consuming Dimetrodon to color in. The paper describing Tambacarnifex unguifalcatus can be viewed by clicking here.

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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