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September 25, 2020 by wpengine

Mesozoic Monthly: Champsosaurus

Good news everyone: it’s September! We’ve made it to month nine of 12! Sometimes it feels like this year will never end. I take comfort in the idea that if life can survive the traumatic Cretaceous-Paleogene (K-Pg) extinction that killed the non-avian dinosaurs, I can make it through 2020. One of the survival champs of the K-Pg extinction was Champsosaurus, a superficially crocodile-like reptile belonging to the extinct group Choristodera.

The skeleton of *Champsosaurus laramiensis* looks superficially like that of a crocodilian, but this is the result of convergent evolution. Choristoderes (like *Champsosaurus*) and crocodilians lived contemporaneously for at least 150 million years, until the choristoderes said “after a while, crocodile!” and went extinct. Photo by Triebold Paleontology, Inc., used with permission.

The class Reptilia encompasses an incredible variety of animals: lizards, snakes, turtles, crocodilians, pterosaurs, dinosaurs, and even birds are just a few of its members. In addition to the familiar reptiles that live today, many other reptile groups thrived for millions of years before eventually going extinct. It’s easy to think of dinosaurs like Tyrannosaurus or Triceratops when we talk about extinct reptile groups, but in reality, many extinct groups of animals with no living relatives escape the public eye. Choristodera, an order within the class Reptilia, is one of these groups. Choristoderes were semi-aquatic or aquatic carnivorous reptiles that evolved during the Mesozoic Era (the Age of Dinosaurs) and died out in the Cenozoic Era (the Age of Mammals). Just because they went extinct does not mean they were unsuccessful; the group survived for at least 150 million years! Like many animals, a rapidly shifting environment was probably the source of their demise. Until that point, choristodere evolution was able to ‘keep up’ with the changing times, including the monumental global changes that came with the K-Pg extinction. The combination of a massive asteroid impact in what’s now Mexico, extensive volcanic activity in India, and worldwide climatic shifts resulted in the extinction of over 75% of all species. Research on choristodere teeth suggests that they beat the odds by adapting to new prey.

When you think of an aquatic carnivorous reptile, you probably think of a crocodilian – and that’d be right! The crocodilian body plan is a very successful build for hunting prey in the water. As another aquatic carnivorous reptile, Champsosaurus evolved similar traits. This is an example of convergent evolution, in which unrelated species develop similar characteristics to deal with comparable circumstances. (You can read about more examples of convergent evolution in the January edition of Mesozoic Monthly about the sauropodomorph dinosaur Ledumahadi.) Some of the shared features between Champsosaurus and crocodilians include long, muscular jaws for catching fish, eyes at the top of the head for peering out of the water, and a flattened tail that was paddled side-to-side for propulsion. Of course, Champsosaurus and the rest of the choristoderes had many features that set them apart as well. Unlike crocodilians, which have bony armor called osteoderms embedded in their skin, choristoderes just had skin covered with tiny scales. In addition, crocodilians have nostrils on top of their snouts so that they can breathe while lurking beneath the surface of the water; choristodere nostrils were at the end of their snouts, so that they could stick the tip of their nose out of the water like a snorkel and breathe from down below.

A right dentary (tooth-bearing lower jaw bone) of *Champsosaurus sp.* from the Upper Cretaceous of Wyoming in Carnegie Museum of Natural History’s Vertebrate Paleontology collection (specimen number CM 96509). The bone is facing upwards, so you’re looking down on the teeth. Check out the dark ‘stripes’ on the enamel of each tooth. These unusual enamel striations are a hallmark of neochoristoderes, the particular choristodere subgroup to which *Champsosaurus* belongs. Photo by Joe Sawchak.

The traits we see in the skeleton of Champsosaurus help paleontologists paint a picture of its behavior. Instead of lurking at the surface of the water, Champsosaurus would wait on the bottom of a shallow lake or stream for prey to come close, lifting the tip of its snout out of the water to breathe. When a tasty fish approached, it would spring off the bottom with its powerful legs and snatch it with its toothy jaws. Despite having strong legs, Champsosaurus was not adapted to a terrestrial lifestyle. In fact, adult males may not have been able to leave the water at all! Fossils attributed to females have more robust hips and hind limbs, allowing them to crawl onto land to lay eggs. According to this hypothesis, the less-robust males would have been restricted to an aquatic-only lifestyle.

Some of the freshwater environments that Champsosaurus inhabited were relatively cold, but that wasn’t a big deal; choristoderes may have been able to regulate their body temperature (a talent known as endothermy or ‘warm-bloodedness’). Crocodilians, by contrast, live in warm, tropical habitats because they are not capable of regulating their body temperature and rely on the sun to warm their bodies (aka ectothermy or ‘cold-bloodedness’). This would explain why choristoderes were able to live further north than crocodilians. However, it seems that crocodilians had the right idea; temperatures around the tropics change less during cooling and warming periods than those at higher latitudes. So, when the current Antarctic ice sheets began to form and the planet started cooling, the temperate choristoderes had to deal with more environmental change than the tropical crocodilians, and finally went extinct. I think the moral of the story is, we would all be handling 2020 better if we lived in the tropics!

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.

CMP Travel Program and Section of Invertebrate Paleontology Promotes the 125th Anniversary of the Carnegie Library of Pittsburgh with an outdoor walking tour

Before Carnegie Museums of Pittsburgh (CMP) reopened to the public on June 28^th, Barbara Tucker, Director of CMP’s Travel Program, talked with me about ways to reengage members and bring them back to the Oakland museums.

With knowledge about my research on the 125^th Anniversary of the founding of the Carnegie Library, Barbara suggested a 90-minute outdoor walking tour around the exterior of the massive building. Starting from where the oldest portion of the building (Portal Entry) meets the newest (Museum of Art) to the front of the historic library entrance, past the Diplodocus carnegii statue, to Forbes Avenue and the entrances of the music hall, natural history museum, and fine arts museum guarded by the statues of the noble quartet.

photo of people standing in a circle in a park — Fig. 1

The tour was advertised on the CMP website under the Travel Program link, https://carnegiemuseums.org/things-to-do/travel-with-us/ and https://carnegiemuseums.org/kollar/, and accurately described as an activity fully compliant with CDC protocols. Within a week, the tour received overwhelming signups, which were organized by date and number of participants by Travel Program assistant Isabel Romanowski. Three tour dates were set in August and several more in September. Special private tours for donors and others in the fall continue to be arranged.

Andrew Carnegie, Founder:

As guide for an exercise that involves close observation of architectural details, I face the challenge of getting participants to imagine this section of Pittsburgh long before any of the structures around in Oakland existed. The library and museums cover five acres of flat bottom land formed by the pre-Ice Age Monongahela River more than 1.2 million years ago. In far more recent times, the land was part of the Mary Schenley Mount Airy tract of 300 acres which was donated to the City of Pittsburgh in 1889 to create Schenley Park in her honor. Andrew Carnegie, (1835 – 1919) industrialist, steel magnate, and philanthropist, in 1895 saw the site as a place to build a complex with a library, fine arts gallery, science museum, and music hall that would represent the noble quartet of literature, art, science, and music.

The Library Tour Themes:

the word Carnegie in gray above the word Carnegie in red — Fig. 2

Tour groups assemble on the dark stone steps outside the Carnegie Museum of Art (CMOA) rear entrance for an introduction focusing on the two connected, but architecturally different buildings: the Beaux-Arts style Carnegie Complex, with the original structure dating to1895, and later addition to 1907, which was built by Longfellow, Alden, and Harlow using Carnegie Steel (Fig. 2), and the modern Carnegie Museum of Art, built by architect Edward Larrabee Barnes in 1974.

Two rock types distinguish the building exteriors. The older portions of the building are clad in a light grey, easily carved, 370 million-year-old Berea Sandstone from Amherst, Ohio, while the exterior and much of the interior of Museum of Art is covered in the 295 million-year-old bluish iridescence Larvikite igneous rock from Larvik, Norway. When Barnes was commissioned to build CMOA, he chose the dark rock to blend with the older building’s coal dust veneer, a grime coating that was removed when the exterior stone was cleaned in 1990.

Landscape Art and Geology:

image of the painting "Cathedral of Learning" by John Kane — Fig. 3

Pittsburgh’s landscape painter, John Kane’s (1860 – 1934), Cathedral of Learning, circa 1930 (Fig. 3), depicts the 150-foot-deep Junction Hollow with its operating railroad. The work also includes many important architectural references, the Schenley Park Bridge (1897), Carnegie Institute’s Bellefield Boiler Plant (designed by Alden and Harlow in 1907 to supply electricity and heat to adjacent buildings), the Carnegie Institute Extension (1907), and a then unfinished Cathedral of Learning. This painting is part of CMOA Fine Arts collections.

image of John Kane painting "Panther Hollow" above a photo of the same spot with geological images on top — Fig. 4

Another John Kane landscape, Panther Hollow, circa 1930 – 1934, (Fig. 4A) in combination with Cathedral of Learning has been used in teaching about the 300 million-year-old geology of Schenley Park (Fig. 4B2) and the pre-Pleistocene Monongahela River that formed the flat bottom landscape of Oakland, and through erosion, Junction Hollow (Fig. 4B1). Kollar and Brezinski 2010, Geology, Landscape, and John Kane’s Landscape Paintings.

Junction Hollow Landscape:

Kane’s Cathedral of Learning (1930) is an idealized green space of Junction Hollow, the Wilmot Street Bridge in the foreground (1907) now replaced with the Charles Anderson Bridge (1940), and Carnegie Tech’s (now Carnegie Mellon University’s) Hamerschlag Hall or Machinery Hall (1912), built by Henry Hornbostel, a Pittsburgh architect. Hornbostel designed a circular Roman temple wrapped about a tall yellow brick smokestack (Fig. 4A). The design is based on the Roman temple of Vesta in Tivoli, Italy, dating to the early 1^st century BC. Hornbostel’s overall campus design focused on connection between art and science, with Junction Hollow representing the geological sciences. The architect Philip Johnston, who built Pittsburgh’s postmodern PPG Place (circa 1984), once contrasted the Bellefield Boiler Plant smokestack as “the ugliest in the world to Machinery Hall’s smokestack as the most beautiful.” In novelist Michael Chabon’s debut novel, The Mysteries of Pittsburgh, (1988) the Bellefield Boiler Plant, termed “the cloud factory” by the narrator, is the setting for a pivotal scene.

Carnegie Library of Pittsburgh (Main):

black and white image of Carnegie Library of Pittsburgh — Fig. 5

The separate institutions we now know as Carnegie Museum of Natural History and Carnegie Museum of Art can track their origins to exhibits and galleries within space now fully occupied by Carnegie Library of Pittsburgh. An image of the Carnegie Library of Pittsburgh in 1902 from the Bellefield Bridge, a structure now buried under the Mary Schenley Memorial Fountain (1918), reveals eclecticism in architectural features (Fig. 5). The west facing frontage doorways and portico of the library features, CARNEGIE LIBRARY, FREE TO THE PEOPLE, and 24 carved writer names. Missing from the names is Carnegie’s favorite poet, Robert Burns, whose statue was dedicated in 1914 on the grounds of Phipps Conservancy. Three separate entrances are served by granite steps of Permian age from Vermont, one for the science museum, one for the Department of Fine Arts, and the third, with distinctive Romanesque round doorways, brass doors with intricate features, and keystone scrolling, for the Library. This entrance was designed by Harlow, who was the draftsman on the McKim, Mead, and White team responsible for the Beaux-Arts Boston Public Library (1895). When the Carnegie Institute Extension was constructed in 1907, the science museum and fine arts museum collections were moved into the new space. The former spaces in the library became the Children’s Room, Pennsylvania Room, and Music Library.

drawing of Carnegie Library of Pittsburgh — Fig. 6

A challenge at this point in the tour involves discussing features that are not visible up close. The Longfellow, Alden, and Harlow’s Italian Renaissance and Beaux-Arts H-shaped parallelogram winning design featured a copula (Fig. 6) on top of the red tile roof that was never built. Eclecticism features include a double apse, a smaller shaped semi-circular extension of the library’s wall on the southside of the building, and larger apse on the north or Forbes Avenue side of the building, with the semicircular Music Hall auditorium, designed by Longfellow. The music hall exterior was structurally changed by the 1907 construction (Fig. 7).

The exterior Berea Sandstone reveals rustication masonry techniques with the cut blocks on the exterior first floor level distinguished by ashlar pillow horizontal border stone, and smooth masonry from the second floor to the cornice below the roof line. The second floor late Gothic style windows are divided by a vertical element called a mullion that helps with rigid support of the window arch and divides the window panels. Two symmetrical Campanile towers that Carnegie called “those donkey ears” were modeled after the San Marco Bell Tower in Venice, Italy. The towers served as an architectural offset to the semicircular exterior walls of the music auditorium and were removed in 1902 for the construction of the Carnegie Institute Extension. The installation of the towers can be interpreted as a tribute to Henry Hobson Richardson’s Allegheny County Courthouse twin towers (1888).

Architects choice of light grey sandstone and red tile roof:

The library’s red tile roof incorporated multiple glass roofs over the library, fine arts galleries, and science museum (all shaded from exterior sunlight today) which typified the Beau-Arts style. Keep in mind, the library did not have electric light. Light was provided by gas lighting and natural sunlight. Longfellow, Alden, and Harlow wrote that “the choice of a red tile roof and grey Ohio (Berea) Sandstone was intentional to contrast with Pittsburgh’s grey skies and the changing seasonal colors of the foliage in Schenley Park.”

The Beaux-Arts Architecture of the Carnegie Institute Extension 1907:

photo of Carnegie Institute extension — Fig. 8

sign that reads Historic Landmark Carnegie Library of Pittsburgh Carnegie Music Hall Carnegie Museum of Natural History Carnegie Museum of Art Built 1895 and 1907 Longellow, Alden & Harlow, Architects Listed in the National Register of Historic Places Department of the Interior, United States of America Pittsburgh History & Landmarks Foundation — Fig. 9

After Longfellow returned to his Boston practice in 1896, Alden and Harlow received the commission to build the Carnegie Institute Extension (1907) (Fig. 8). Their efforts created one of the great Beaux-Arts building in the United States. As Cynthia Field, Smithsonian Architecture Historian, stated in 1985, “the building itself is the greatest object of the entire museum collection.” Formal recognition of the building’s architectural importance exists in two historic landmark plagues placed outside of the Carnegie Library entrance and the Museums’ Carriage Drive entrance (Fig. 9).

New exterior features of the 1907 extension work included the replacement of the red tile roof with copper, the addition of an armillary sphere, the construction, with a colonnade of solid Corinthian fluted columns of Berea Sandstone, four portico porches over the main entrances to the library, music hall, natural history and art museum, and eastside of building (now removed), and the creation, along Forbes Avenue, of a main Carriage Drive entrance with direct access to the galleries. The carved names of authors, artists, musicians, and scientists in the buildings’ entablature, a Victorian era practice, extends around the building from the library’s southeast corner to the music hall entrance, and natural history and the fine arts entrances.

Also notable along Forbes Avenue are John Massey Rhind’s noble quartet statues that guard the Music Hall and Natural History and Art entrances. The four male figures all seated in classic Greek chairs are Michelangelo (art), Shakespeare (literature), Bach (music), and Galileo (science). Standing three stories above the quartet on the edge of the roof, four groups of female allegorical figures represent literature, music, art, and science as well. The bronze figures were casted in Naples, Italy in 1907 (Fig 8).

Inside the 1907 Architecture and Building Stones:

The architects created 13 new interior spaces where three grand spaces stand out for specific architecture styles such as, the Beaux-Arts Grand Staircase (voted in 2018 as the 8^th best museum staircase in the world), the Neoclassical Hall of Sculpture, and neo-Baroque Music Hall Foyer. The extension used 32 varieties of marbles and fossil limestones, many from antiquity, quarried and imported from Algeria, Croatia, France, Greece, Ireland, Italy, and the United States.

Since 2004, the collaboration between the CMP Travel Program and the Section of Invertebrate Paleontology has been highly successful reaching out to our members and patrons. This summer’s tours generated some particularly appreciative comments:

The Carnegie’s resident scientists are a defining characteristic of this noble institution. Might be an anachronism in an era when museums are focused on providing ‘destination’ entertainment and hosting special events for swells, but while treasures like Dr. Kollar are still on staff, it’s a splendid idea to facilitate interaction between them and museum visitors. Congratulations on a most enjoyable program. -Ron Sommer

Albert was very informative and interesting. I found it most valuable learning the history of the area. -Janet Seifert

I can’t stress enough how unusual and interesting it was to have a geologist give us the tour. It had never occurred to me before that there’s so much one can learn about building materials from a geologist. -Neepa Majumdar

Albert D. Kollar is Collection Manager and Carnegie’s Historian of the Carnegie’s Building Stones. Barbara Tucker is Director of Carnegie Travel Program.

The Strange Saga of Spinosaurus, the Semiaquatic Dinosaurian Superpredator

I’ve been captivated by dinosaurs for as long as I can remember. My parents tell me that I told them that I wanted to be a paleontologist as early as age four. Naturally, then, I had lots and lots of books about dinosaurs when I was a boy growing up during the 1980s. One of the dinosaurs that always fascinated me the most was Spinosaurus aegyptiacus. Found in 1912 in the Bahariya Oasis of the Western Desert of Egypt (could anyplace sound more exotic to a small-town kid from upstate New York?!), Spinosaurus was originally known from a highly incomplete but also very large and extremely distinctive partial skeleton found in a middle Cretaceous-aged (roughly 95-million-year-old) rock layer in the oasis. Among the few skeletal elements known were part of a strangely shaped (for a dinosaur) lower jaw, some crocodile-like teeth, and most strikingly, several back vertebrae that each sported tall spines, some of them measuring nearly six feet. These spines clearly impressed Ernst Stromer von Reichenbach, the German paleontologist who studied the skeleton and gave the animal its name in a 1915 publication. Tragically, however, that original Spinosaurus skeleton—and all of Stromer’s other dinosaur fossils from Egypt—were destroyed during the Second World War, more specifically in a British Royal Air Force bombing of Munich on April 24, 1944. The story of Stromer’s lost dinosaurs found its way into many a children’s book, including several that I read cover-to-cover. As such, the tale took on near-legendary status for me, and, I’m sure, many other young dinosaur enthusiasts around the world. Here was an absolutely extraordinary dinosaur from a faraway land, similar in size to the gargantuan Tyrannosaurus rex, but clearly very different from all other predatory dinosaurs known at the time – and it was represented only by a few teeth and bones that had been blasted into oblivion decades ago and so now existed only as pictures in books.

A scan of my photocopy of plate I of Ernst Stromer’s original 1915 publication on *Spinosaurus aegyptiacus*, showing some of the teeth and bones preserved in the holotype (= name-bearing) partial skeleton, discovered in 1912 in Egypt’s Bahariya Oasis. Check out the long spines on the back vertebrae at lower left!

Stromer’s conception of *Spinosaurus*, as depicted in a 1936 publication and on a glass slide of his that colleagues of mine scanned during our visit to the Paläontologisches Museum München in Munich, Germany in 2001. Stromer knew this animal was big, as evidenced by the human skeleton he included for scale. Interestingly, too, he reconstructed *Spinosaurus* with unusual proportions for a carnivorous dinosaur, such as an abnormally elongate torso and short hind limbs. We’ll come back to those odd proportions a little later…

When I arrived in graduate school at the University of Pennsylvania in 1997, one of the first things I did was make a lengthy list of all the paleontological sites I was interested in exploring, ranked by their potential (in my mind, at least) to produce scientifically significant finds. The Bahariya Oasis and the search for a ‘replacement Spinosaurus’ quickly rose to the top of the list. Amazingly, no one had ever found—or at least officially reported—new dinosaur fossils in the oasis in the more than half-century since Stromer’s beasts were obliterated during that fateful airstrike. A need to keep this post to a reasonable length prevents me from describing the stars that had to align to make this happen, but in January 2000 I found myself in the Bahariya Oasis—one of the places I’d dreamed about going since I was a small child—as part of the first significant ‘dinosaur hunt’ to take place at the site since the early 20^th century. It was bittersweet, though, in the sense that we never really found that ‘replacement Spinosaurus’ I’d fantasized about – all we ever discovered of that creature were a few isolated, fragmentary teeth and bones (and, in a very different location, a couple previously unpublished photos of the original skeleton in a Munich archive). We did find and dig up a gigantic new species of long-necked, plant-eating sauropod dinosaur, Paralititan stromeri, a creature that to this day is one of the largest land animals of any kind that’s ever been found, anywhere – but that’s another story for another time.

One of the rare contributions that I personally have made to scientific knowledge of *Spinosaurus*: a glass slide showing the only known photo of the right dentary (tooth-bearing lower jaw bone) of the original, name-bearing partial skeleton from Egypt. Like all of Stromer’s Egyptian dinosaur material, this specimen (including this bone) was destroyed in a British air raid on Munich during World War II. Several colleagues and I ‘rediscovered’ this photo—which nobody apparently knew existed—in an archive at the Paläontologisches Museum München in 2001. We published it and one other previously unknown photo of the Spinosaurus type specimen in a 2006 paper in the Journal of Paleontology.

A much younger yours truly digging up the incomplete left humerus (upper arm bone) of the gigantic sauropod (long-necked herbivorous dinosaur) *Paralititan stromeri* in the Bahariya Oasis of Egypt, February 2000. *Paralititan* is one of the largest dinosaurs ever discovered – a nice ‘consolation prize’ given that we didn’t find much of *Spinosaurus* during our expeditions to Bahariya. (A cast replica of the complete right humerus of *Paralititan* is on display in *PaleoLab* at Carnegie Museum of Natural History.) Credit: Josh Smith.

Back to the matter at hand, meaning Spinosaurus. Fast-forward to 2011. I had the honor of serving as the external thesis examiner for Nizar Ibrahim, a promising doctoral student at University College Dublin in Ireland. I’d known Nizar for years, ever since he reached out to me by email while an undergraduate at the University of Bristol, England, to discuss our mutual interests in African Cretaceous dinosaurs. Nizar’s Ph.D. thesis was on dinosaurs and other middle Cretaceous-aged vertebrates from the celebrated Kem Kem beds of southeastern Morocco, a set of rocks that had yielded a fossil fauna very similar to, though seemingly more diverse than, that of the Bahariya Oasis. Among the many finds that Nizar documented in his colossal thesis were intriguing new remains of Spinosaurus. I went to Dublin to participate in his successful thesis defense, and afterward, he and I hit up some of the city’s finest public houses to celebrate (no surprise for those who know me). Over a pitcher of yummy Irish stout, he told me an exciting story – he and his team had lately discovered not just isolated bones of Spinosaurus in Morocco, but parts of a probable new skeleton. If so, this find would be the first skeleton since Stromer, and moreover would be exceedingly important given how little was known about Spinosaurus, even as recently as the early 2010s. The more parts we paleontologists have of a given fossil animal, the more we can generally learn about it, so the prospect of a new and relatively complete Spinosaurus skeleton—in other words, many bones belonging to a single individual dinosaur—was thrilling to say the least.

Again I’ll skip details for brevity’s sake, but fast-forward once again, to 2014. I was contacted by an editor of Science—one of the foremost scientific journals in the world—to peer-review a paper that had been submitted by (you guessed it!) Nizar and a long list of collaborators describing that new skeleton of Spinosaurus that he’d told me about over beers in Ireland three years before. Nizar and team had revisited the quarry and it had panned out in a big way. From this one, single individual Spinosaurus—again, the first associated skeleton of this dinosaur to have been found in roughly a century—they had bones from the skull, backbone (including a few of those famously long-spined vertebrae!), forelimb, pelvis, and hind limb. More importantly, these ‘new’ bones revealed that Spinosaurus was even more bizarre than anyone imagined! We already knew, from Stromer’s specimen and other, isolated finds made through the years, that the shapes of the skull and back were really weird for a predatory dinosaur. Now, the new skeleton showed that the bones were remarkably dense, the hind legs were oddly short, and the hind feet may have been webbed! All of this led Nizar and colleagues to propose that Spinosaurus may have been semiaquatic; in other words, that its lifestyle was much more comparable to that of a modern-day alligator or crocodile than it was to a more ‘typical’ land-living predatory dinosaur such as T. rex. Other evidence for an affinity to watery habitats had been found in Spinosaurus and closely related dinosaurs (known, perhaps unsurprisingly, as spinosaurids) before, but this was, in my mind, the most convincing case yet made that these animals spent significant amounts of their time at least partly submerged in lakes and rivers. The paper was published in Science a few months later, accompanied by a cover story in National Geographic magazine and a special on the venerable PBS TV series NOVA. Almost exactly one hundred years after it had been named, Spinosaurus had become a celebrity.

Nizar Ibrahim and colleagues’ initial conception of *Spinosaurus aegyptiacus* in the flesh, released to coincide with the publication of their *Science* paper in 2014. Two aspects stand out: as Stromer already knew (see his skeletal reconstruction above), the animal is enormous, but it was more oddly proportioned than even he had imagined. Note also the ‘regular-looking’ (for a dinosaur) tail, and read on. Credit: Davide Bonadonna.

Semiaquatic *Spinosaurus* chowing down on a tasty lungfish in what is now northern Africa some 95 million years ago. Italian paleoartist Davide Bonadonna has produced some of the most beautiful and accurate modern depictions of this extraordinary dinosaur, and I’m grateful to him for letting me reproduce his art here.

But the story didn’t end there. Some prominent paleontologists criticized Nizar and colleagues’ semiaquatic interpretation of Spinosaurus. These opinions weren’t a final judgment. Instead, this is just how science works: we scientists propose ideas, or hypotheses—in this case, that Spinosaurus lived and behaved more like a crocodile than your garden-variety carnivorous dinosaur—and then test these hypotheses by reevaluating the existing evidence and/or bringing new information to light. If a hypothesis repeatedly stands up to testing, then it gradually gets incorporated into the body of knowledge. Other paleontologists presented evidence that they claimed refuted the semiaquatic hypothesis, but Nizar and team eventually countered with new data of their own. In late 2019, another prominent scientific journal—this time it was Nature—came calling, asking me to review a second paper by Nizar et al. on Spinosaurus. What, I thought, could these researchers have to say about this dinosaur that they hadn’t already said before? Well, as it turns out, Nizar and colleagues had kept digging at their Spinosaurus skeleton site, and incredibly, they’d continued to find important new bones belonging to the same specimen. Among these post-2014 finds was the almost complete tail. When I saw what it looked like (via an illustration in their paper), I literally laughed out loud with surprise and delight. Somehow, the shape of the Spinosaurus tail Nizar’s team had discovered—the first even reasonably complete tail of this dinosaur to have ever been unearthed—was simultaneously both unexpected and predictable. It looked really dissimilar from the tails of other predatory dinosaurs, but it was nearly exactly like what one might expect for a dinosaur that used its tail to propel itself through water. In other words, the tall, fin-like tail of Spinosaurus looked more like that of a supersized alligator or newt than that of T. rex.

Nizar and team’s Nature paper on their Spinosaurus tail was published this past April 29. Is it the last word on this dinosaur and its mode of life? Most certainly not, but the evidence is now stronger than ever—in my opinion, very strong—that Spinosaurus spent more time in the water than any other non-avian (= non-bird) dinosaur that we currently know about.

The modern view of *Spinosaurus*, not as a ‘regular’ predatory dinosaur, but rather as a specialized semiaquatic hunter that spent much of its life in the water. Self-serving side note: the three smaller, spiky-looking fish are *Bawitius bartheli*, a polypterid (an archaic, still-extant group of thick-scaled ray-finned fishes) that several colleagues and I named in 2012 from fossils found in the Bahariya Oasis. The larger fish at lower left is the giant coelacanth *Axelrodichthys* (sometimes called *Mawsonia*) *libyca*. Credit: Davide Bonadonna.

Two *Spinosaurus* invite the sawfish *Onchopristis numidus* to lunch in what’s now northern Africa some 95 million years ago. Look at those fin-like *Spinosaurus* tails! Credit: Davide Bonadonna/National Geographic.

Nizar (who’s a Research Associate here at Carnegie Museum of Natural History), myself, and our many colleagues and collaborators are continuing to study the mysterious dinosaurs and other fossil vertebrates from the middle and Late Cretaceous of northern Africa. Indeed, Nizar and I have several collaborative papers in the works right now, and I’m also working with an amazing team of paleontologists at Mansoura University on multiple new Egyptian fossil finds. It’s a good bet that African Cretaceous dinosaurs even stranger than Spinosaurus are still out there, waiting to be discovered!

Further reading/watching:

Nothdurft, W. E., with J. B. Smith, M. C. Lamanna, K. J. Lacovara, J. C. Poole, and J. R. Smith. 2002. The Lost Dinosaurs of Egypt. Random House, New York, 256 pp.

Smith, J. B., M. C. Lamanna, H. Mayr, and K. J. Lacovara. 2006. New information regarding the holotype of Spinosaurus aegyptiacus Stromer, 1915. Journal of Paleontology 80:400–406.

Ibrahim, N., P. C. Sereno, C. Dal Sasso, S. Maganuco, M. Fabbri, D. M. Martill, S. Zouhri, N. Myhrvold, and D. A. Iurino. 2014. Semiaquatic adaptations in a giant predatory dinosaur. Science 345:1613–1616.

Bigger Than T. rex (NOVA documentary): https://www.pbs.org/wgbh/nova/video/bigger-than-t-rex/

Henderson, D. M. 2018. A buoyancy, balance and stability challenge to the hypothesis of a semi-aquatic Spinosaurus Stromer, 1915 (Dinosauria: Theropoda). PeerJ 6:e5409.

Ibrahim, N., S. Maganuco, C. Dal Sasso, M. Fabbri, M. Auditore, G. Bindellini, D. M. Martill, S. Zouhri, D. A. Mattarelli, D. M. Unwin, J. Wiemann, D. Bonadonna, A. Amane, J. Jakubczak, U. Joger, G. V. Lauder, and S.E. Pierce. 2020. Tail-propelled aquatic locomotion in a theropod dinosaur. Nature 581:67–70.

Matt Lamanna is Mary R. Dawson Associate Curator and Head of 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.

Egypt and the Nile

Over the course of some five millennia the ancient Egyptians developed a distinctive material culture shaped in large part by their local geography, natural resources, and relationship with the Nile River. In the 5^th Century BCE, the Greek historian Herodotus noted that “any sensible person” could see that Lower Egypt was a “gift of the river” (Herodotus, 2.5). While his comments were limited to the areas in the north and in the Delta, they really ring true for all the Nile River Valley. Every aspect of life in Egypt depended on the river – the Nile provided food and resources, land for agriculture, a means of travel, and was critical in the transportation of materials for building projects and other large-scale endeavors. It was a critical lifeline that literally brought life to the desert.

Map of Ancient Egypt (www.shutterstock.com 211163719)

The modern name of the Nile River comes from the Greek Nelios, but the Egyptians called it Iteru or “River.” The Nile is the longest river in the world, measuring some 6,825 km. The Nile River System has three main branches – the White Nile, the Blue Nile, and the Atbara river. The White Nile, the river’s headwaters, flows from Lake Victoria and Lake Albert. The Blue Nile brings about the inundation or annual flood and provides most of the river’s water and silt. The Atbara river has less of an impact, as it flows only occasionally.

In the south, the Nile has a series of six main cataracts, which begin at the site of Aswan. A cataract is a shallow stretch of turbulent waters formed where flowing waters encounter resistant rock layers. In the case of the Nile cataracts, large outcroppings of granite make the flow of the river unpredictable and much more difficult to traverse by boat. The cataract system created a natural boundary at Aswan, separating Egypt from its southern neighbor, Nubia.

Ancient Egypt was located in Northeastern Africa and had four clear geographic zones: the Delta, the Western Desert, the Eastern Desert, and the Nile Valley. Each of these zones had its own natural environment and its own role within the Egyptian State. Cities could only flourish in the Nile Delta, the Nile Valley, or desert oases, where people had access to water, land, and key resources. The ancient Egyptians, who were always keen observers of nature, often associated the Nile Valley with life and abundance and the neighboring deserts with death and chaos.

Kemet or, “black land,” denotes the rich, fertile land of the Nile Valley, while Deshret, or “red land,” refers to the hot, dry desert. The contrast between the red land and the black land was not just visible or geographic, it effected the Egyptians’ everyday lives. The dry climate of the desert, for example, made it an ideal location for cemeteries. There, the annual Nile flood would not disturb people’s graves and the dry climate acted to preserve tombs and their contents. Good preservation and the fact that most people do not live in the desert, are the main reasons that so much of what archaeologists and anthropologists study comes from a funerary context.

View with the Nile River Valley in the foreground and the desert cliffs in the background. (www.shutterstock.com 1082850872)

The landscapes of Upper and Lower Egypt also differ. The Egyptian word Tawy, means “Two Lands” – this refers to the two main regions of ancient Egypt, Upper and Lower Egypt. Lower Egypt is in the north and contains the Nile Delta, while Upper Egypt contains areas to the South. These two designations may seem counterintuitive to their physical locations, but they reflect the flow of the Nile River, from South to North.

The expansive floodplain of the Nile Delta and the very narrow band of fertile land present in the Nile Valley led to different ways of life. In the Nile Delta for example, the Egyptians constructed their towns and cemeteries on turtlebacks; natural highpoints in the landscape that became islands during the inundation. In addition, the location of the Delta along the Mediterranean and at the entry point into the Levant made it an important area for trade and international contacts. The Delta was a very multi-cultural region throughout Egyptian history.

Ancient Egyptian Sema-Tawy – represents the eternal unification of Upper and Lower Egypt (www.shutterstock.com 1778750570).

The Egyptians thought of the king as the unifier of the “Two Lands.” One of the king’s primary roles was to keep Upper and Lower Egypt united; the Egyptians expressed this visually using something we call the sema-tawy motif. Here you can see two Nile gods symbolically uniting the lands of Upper and Lower Egypt – each depicted in the form of their characteristic plant, the papyrus for Lower Egypt and the lotus for Upper.

The Egyptians constructed their calendar around the yearly cycle of the Nile. It included three main seasons: Akhet, the period of the Nile’s inundation, Peret, the growing season, and Shemu, harvest season. The Egyptians made Nilometers to measure and track the height of the annual inundation – they used the recorded readings from these Nilometers much like more contemporary farmers would use almanacs. One particularly well-preserved example is located on Elephantine Island at Aswan.

The close connection between the Egyptians the Nile River led them to identify a number of Egyptian gods with aspects of the river, its annual flood, and the fertility and abundance associated with them. Hapi, for example, is the incarnation of the life force that the Nile provides; he also symbolizes the annual inundation of the Nile. His round belly and folds of skin represent abundance. Osiris, who is most often recognized in his role associated with the afterlife, is fundamentally a god of regeneration and rebirth. Artists often depicted him with black skin, linking him to the fertility of the Nile River and its lifegiving silt. The broader natural world was a further source of inspiration for Egyptian religion.

The Nile was also an important highway, it was the easiest way to travel and played an essential role in mining expeditions, trade, architectural projects, and general travel. The Egyptians were expert boat builders; images of boats are some of the earliest designs that appear on Egyptian Predynastic Vessels dating to ca. 3500-3300 B.C.E. River access decreased the time and number of individuals needed for the transportation of large objects, like stones, obelisks, and architectural elements. Boats were also common in the funerary religion as well – as a part of the funeral itself and for the afterlife.

Although I’ve only been able to touch on a few key elements here, the natural environment of Egypt and the Nile River impacted every aspect of life in ancient Egypt. The river’s floodplain, water, and silt provided the foundation for civilization and served as a source of inspiration for the people who inhabited northeastern Africa during this pivotal period in history.

Lisa Saladino Haney is Postdoctoral Assistant Curator of Egypt on the Nile at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Overwintering for Amphibians and Reptiles

by Amanda Martin

With Autumn upon us, temperatures are dropping, and it is getting colder out. Especially in the northern regions, amphibians and reptiles need to prepare for brumation (essentially, hibernation for ectotherms). Ectotherms like frogs, salamanders, snakes, and turtles are highly sensitive to changes in their environment and need to stay warm by actively moving in and out of areas with heat. When temperatures increase, ectotherm metabolism increases, and when temperatures go down, so does their metabolism. But how do they survive during winter, won’t they freeze?

Fig. 1. Eastern garter snake. Photo by A.K. Martin.

Many snakes, like eastern garter snakes (Fig. 1) find shelters called hibernacula and curl up inside, sometimes intermixed with other snake species. These hibernacula are often small mammal burrows, dens, or tunnels below the frost line. During winter, typically between October and March, several hundred individuals will gather in the same den, tightly coiling their bodies together to stay warm enough to survive. They stop eating during this period because it is too cold to properly digest food and will stay hydrated by absorbing moisture through their scaly skin. Even though snakes are awake and sluggishly active, they expend very little energy during this time and do not lose much weight.

Fig. 2. Eastern box turtle. Photo by A.K. Martin.

Turtles, on the other hand, are a bit different. Aquatic turtles survive winter underwater, and the terrestrial eastern box turtle (Fig. 2) buries itself underground by digging into the soil. One extreme overwintering survivor is the painted turtle, which spends most of its time in ponds and slow-moving freshwater. When these ponds freeze, painted turtles bury themselves up to 45 cm (nearly 18 inches) in mud beneath the pond’s surface. Amazingly, these turtles can survive for months in low or no oxygen environments. During warmer months, they breathe air, but when submerged for overwintering they absorb oxygen through the thin skin of their cloaca, a phenomenon called cloacal respiration.

Fig. 3. Wood frog. Photo by A.K. Martin.

Another amazing overwintering feat is the freeze tolerance of wood frogs (Fig. 3) which can become frogsicles! Wood frogs are unable to bury themselves completely, like turtles, so part of their body is often exposed when trying to stay underneath the mud. This is beneficial for obtaining oxygen through their skin. However, they still need to avoid freezing and will move around to warmer areas as needed. Many frogs stay in burrows or under leaf litter to escape the frost, but wood frogs will stay at shallower depths because they have high concentrations of glucose, which produces an “antifreeze” effect. This protects their organs when over two-thirds of their body freezes!

Fig. 4. Red-backed Salamander. Photo by A.K. Martin.

Other amphibians, like salamanders, do not have freeze tolerance like the wood frog. Red-backed salamanders (Fig. 4) are one of the most abundant species in the eastern United States. They are typically found underneath logs and leaf litter at shallow depths, but during winter when temperatures drop below 30°F, they travel as much as 15 inches under the ground in animal burrows. Other species, like spotted salamanders, will also look for deep burrows that are below the frost line.

In early spring when temperatures warm, amphibians and reptiles emerge from overwintering to look for basking sites, sunny spots to warm themselves. With warmer temperatures, the prey of many of these species also become more available. Garter snakes will look for slugs, earthworms, amphibians, minnows, and rodents, for example, and red-backed salamanders will eat a wide variety of invertebrates, such as spiders, worms, snails, and insects. The exact timing of emergence for amphibians and reptiles depends on a given year’s weather, resulting in variable emergence times from year to year that correspond to temperature. Not every individual makes it to the spring, but it is amazing that species that are so dependent on the temperature of their environment are capable of surviving up north!

Written by Amanda Martin, Post-doctoral Researcher in the Section of Amphibians and Reptiles at Carnegie Museum of Natural History. Edited by Jennifer Sheridan, Assistant Curator in the Section of Amphibians and Reptiles at Carnegie Museum of Natural History. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

Feeding the Monster in the Sewer

Water is a resource that I often take for granted. I take daily showers, wash my dishes, and do my laundry without a second thought to the amount or quality of water that is used. I only experience small aspects of the natural water cycle on a daily basis, from a bit of condensation on a cold glass of water to the sporadic downfall of rain that occurs in Pittsburgh. The water cycle that I’ve learned about in school can be boiled down to: precipitation, surface runoff, infiltration, evaporation, and condensation; but how do I, as a human being, fit into all of this? What is the human water cycle and how have parts of the water cycle changed within the Anthropocene?

drawing of the city water cycle from waste water to drinking water

As intrigued as I was, I didn’t know enough about my own impact on the water cycle, so I took a deeper dive into learning about what was actually happening to the water that I used. In order to explore the concept of the human water cycle I needed to start by looking at infrastructure. In the case of water infrastructure, outside of irrigation, the water purification systems and sewage systems are some of the most impactful additions human beings have included into the planet’s water cycle. These infrastructural systems span thousands and thousands of miles underground, connecting houses, neighborhoods, and cities. And yet, at least for me, there was a vast mental disconnect between the water that flows underneath us and the water that we consume. I wasn’t sure how to visualize something that was happening underground, hidden away from sight. That’s when I learned about fatbergs.

In 2017 an 820 foot long mass weighing 130 metric tons was discovered in the sewers of Whitechapel in London, England. The same type of mass, weighing 42 metric tons was found in Melbourne, Australia during the outbreak of the COVID-19 virus, most likely due to the flushing of “toilet paper substitutes” (i.e. paper towels, sanitary products, facial tissues). These masses are called fatbergs and can be found in most major cities, especially those with older sewage systems like Pittsburgh. A fatberg is a solidified mass of fat, formed overtime in sewers, that sticks to the build-up of un-flushable sewage. Fatbergs cost hundreds of thousands of dollars to remove, and also reduce river and stream water quality by making sewer overflows more likely. In the Pittsburgh Area, whenever the combined storm and sanitary sewer system is overloaded, excess flow is dumped directly into the rivers.

drawing of a pipe with a fatberg forming in it

Fatbergs are a human phenomenon that directly impacts both us and the greater environment. The sewer overflows that they cause impact both the built and natural environment, introducing pollutants such as human waste from our toilets and fats from our kitchen sinks into the living domain. But as harmful as they are, they can be easily prevented.

How, you ask? The solution is simple… don’t flush down anything other than toilet paper and bodily waste. But why? What makes toilet paper any different from other paper-like materials? The answer lies in the unique quality of the material that toilet paper is made up of. Unlike paper towels that use long fiber pulps, which improves the strength and absorptivity of the material, and facial tissues that contain additives that hold the fibers together, toilet paper is made using approximately 70% hardwood pulps with short fibers and 30% softwood pulps with longer fibers. Due to the hardwood pulps, once the toilet paper makes contact with water, the short fibers, which also help keep the toilet paper soft to touch, are able to untangle and fall away into smaller fragments, eventually dissolving into tiny bundles of short fiber that can easily flow through the sewage system.

jar, wet paper, and a drawing of paper fibers

Objects like ‘flushable wipes’, unlike toilet paper, take hours to days to break down. This means that just because we are able to flush something down, doesn’t necessarily make it safe for sewer and septic systems. If you want to try an experiment to explore this concept, try putting ‘flushable’ wipes and toilet paper into two separate containers of water. See for yourself what happens.

Fatbergs are all the more relevant to us during the times of the pandemic, especially in the United States. As people stay home, more objects that aren’t healthy for the sewage system are being flushed. Think about the times you flushed anything other than toilet paper. Are you feeding a potential fatberg in your neighborhood?

Daniel Noh is an intern for the Center for Anthropocene Studies, 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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