Carnegie Museum of Natural History

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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.

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The Bromacker Fossil Project Part X: Tambaroter carrolli, an amphibian with a wedge-shaped head

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, and Part IX. 

Thomas Martens at the construction site for a new store in Tambach-Dietharz where he found fossils by checking loose pieces of rock on the excavation floor. Photo by Stephanie Martens, 2008.

Paleontologist Thomas Martens has an amazing ability to find fossils. After he discovered the first vertebrate fossils at the Bromacker site in an abandoned commercial quarry in 1974, he and his father Max found additional fossils in the bottom of a deep pit they’d dug with hand tools, an excavation that Dave Berman, Stuart Sumida, and I fondly dubbed the “elevator shaft.” Years later, Thomas used funding from the German federal government to drill rock cores in the field surrounding the Bromacker quarry to help understand the geology of the fossil deposit. Amazingly, at one of the spots Thomas had selected, the drill core penetrated a skeleton of Diadectes absitus. So, it wasn’t surprising that in 2008 Thomas found a skull and partial skeleton of D. absitus and a small skull of a fossil animal new to science at a construction site for a new store in the nearby village of Tambach-Dietharz.

Dave Berman (left) and Stuart Sumida (right) pose with a shopping cart in front of the Netto Discount Store, which was built in the excavation site where Tambaroter was found. Rocks of the Tambach Formation can be seen behind the retaining wall. Photo by the author, 2008.

It makes sense, however, that vertebrate fossils were found close to the Bromacker quarry. Fossils from the Bromacker were preserved in the Tambach Formation, a 200–400-foot-thick unit of sediments that were deposited in the small intermontane Tambach Basin about 290—283 million years ago during the Early Permian Epoch. The Tambach Basin covered an area of about 155 square miles and was internally drained; that is, there were no rivers or streams flowing into and out of the basin. During periods of extremely heavy rain, water and mud would flow down the basin sides in what are called sheet floods and pool in the basin center, which is where the present day Bromacker quarry and Tambach-Dietharz are thought to be located. Any animals killed during these events would be carried by the sheet floods to the basin center where they’d have been quickly and deeply buried in mud settling out of the ponded water and later become fossilized. It is assumed that animals captured by the sheet flood events inhabited the Tambach Basin, because carcasses couldn’t have been carried into the basin by rivers and streams.

Map of Germany with inset showing the Bromacker locality and the nearby town of Tambach-Dietharz. Although the Tambach Basin in which the Tambach Formation was deposited covers about 155 square miles, outcrops of the Tambach Formation today occur in an area of only about 31 square miles.

While preparing Bromacker fossils, I’d typically read literature related to the fossil I was working on, write notes on what I thought were important features in the fossil, and give my notes to the person leading the project. When Dave was the lead, we’d typically have lots of discussion about certain features preserved in the animal, conversations that often directed the course of preparation. This time, in addition to preparing the new find, I was designated as the lead author for the publication that would name and describe it.

View of the underside of the skull of Tambaroter carrolli before preparation. The shiny area surrounding the skull is glue, which I applied to a crack to stabilize the specimen before preparation could begin. I had to free the skull from the surrounding rock before exposing as much of it as possible through preparation. Photo by the author, 2008.

Tambaroter is a member of the Microsauria, a diverse group of small amphibians that were once thought to be reptiles, a hypothesis that some paleontologists are currently revisiting. Microsaurs inhabited a variety of habitats and exhibited a range of body forms. Some were highly terrestrial with limb proportions similar to those of lizards, whereas others were aquatic and had elongated bodies and reduced girdles and limbs. Still others were adapted for burrowing or rooting through leaf litter. Tambaroter belongs to this latter-most group, which is named Recumbirostra for their recurved snout, in which the front of the mouth is overhung by the snout.

Photographs and line drawings of the skull of Tambaroter carrolli in (clockwise from upper left) dorsal (top), ventral (underside), and left lateral (side) views. Photographs by the author, 2008 and drawings by the author and modified from Henrici et al., 2011.

Tambaroter is member of the recumbirostran subgroup Ostodolepidae. I coined the name Tambaroter, which is derived from “Tamb,” for the Tambach Formation, and the Greek “aroter,” meaning plowman, in reference to the snout shape. Two previously named ostodolepids, Micraroter and Nannaroter, have the “aroter, suffix in their name, so usage of the “aroter” suffix was a continuation of this. The species name, carrolli, honors microsaur expert Robert Carroll (then Curator Emeritus at the Redpath Museum, McGill University, Montreal, Canada).

Skulls of representative ostodolepid microsaurs from geologically oldest (left) to youngest (right). A reconstruction drawing of the skull of Tambaroter was used instead of a photograph for comparison because the original fossil skull is extremely flattened (see previous image). Photographs, except for that of Nannaroter, by the author, 2009. The photograph of Nannaroter was modified from Anderson et al., 2009. Tambaroter skull reconstruction by the author and modified from Henrici et al., 2011. Scale bar of the tiny Nannaroter and other ostodolepids equals 1 cm.

When Tambaroter was published on in 2011, it was the first ostodolepid to be found outside of the USA (the others are from Oklahoma and Texas) and is the oldest one known. Other, possible ostodolepids have since been described from the American Midwest and Germany. All ostodolepids have a wedge-shaped skull and recumbent snout, which is accentuated in Pelodosotis. Based on these features, scientists think that ostodolepids burrowed or searched for worms and other prey in leaf litter. Remarkably, the skull of the tiny Nannaroter is so strongly built that it could have withstood burrowing headfirst into the ground by using its shovel-like snout to loosen dirt and its broad, flat head to push soil against the burrow ceiling. Because the sutures between individual skull bones in the Tambaroter type specimen are not tightly fused together, we think it belonged to a juvenile, so we don’t know if the adult skull would’ve been as strongly built as that of Nannaroter.

Life drawing of the ostodolepid microsaur Pelodosotis elongatum, which is known by a nearly complete specimen. Tambaroter probably had a similar body shape, though its skull would not have been as strongly wedge-shaped. Drawing modified by Carnegie Museum of Natural History Scientific Illustrator Andrew McAfee from outline drawing in Carroll and Gaskill (1978).

Stay tuned for my next post, which will feature one of the Bromacker’s top carnivores. To learn more about Tambaroter, read the publication that described the animal 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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The Bromacker Fossil Project Part XI: Dimetrodon teutonis, an apex predator

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Collected on this Day in 1967: Fall blooms rival those of spring

photo of aster flowers with white petals

In the northeastern United States, we often think of spring as a time for wildflowers.  But the fall is, too.  

It is easy to be distracted by the beautiful fall foliage, when our landscape turns brilliant shades of red, orange, and yellow.  But when many plants are shutting down for the winter, others are just kicking into gear.

Many wildflower species bloom well into fall, both in open areas and in the forest understory.  One group of plants are the fall blooming “asters.”  In same plant family as sunflowers and dandelions (Asteraceae), Aster was once a very large plant genus in our native North American flora (somewhere along the lines of >175 species!), but as we learned more about the evolutionary relationships of these plants, they have since been split into multiple genera (plural of genus). In fact, there is only one “true” Aster in Pennsylvania, Tatarian aster (Aster tataricus), which is actually not even native to Pennsylvania!  Regardless of the scientific name, these plants are commonly referred to as asters.  And they put on quite an autumn show in Pennsylvania.

dried specimen of aster flower from Carnegie Museum of Natural History herbarium

Perhaps one of the most common woodland asters in Pennsylvania is white wood aster (Eurybia divaricata, formerly known as Aster divaricatus).  This specimen was collected September 29, 1967 by N.R. Farnsworth in Pittsburgh’s Schenley Park.  This species can still be found in Schenley Park, and many parks, woodlands, and wooded roadsides across Eastern North America.

Fall foliage is beautiful in Pennsylvania.  But don’t forget to look down at the flowers, too!

Find this white wood aster specimen here: https://midatlanticherbaria.org/portal/collections/individual/index.php?occid=11826562

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.

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Herbarium Specimens Hold More Information Than We Realize

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Herbarium specimens hold more information than we realize

The first herbarium I visited was the Pringle Herbarium at the University of Vermont as part of an undergraduate class on plant taxonomy and systematics. Prior to this visit, I assumed herbaria were fairly mundane collections of dead, dry, flattened plants, and that they couldn’t possibly interest me as much as emerald-green plants thriving in the wild. However, within moments of entering the Pringle Herbarium, I was captivated by the football-sized cones of the sugar pine (Pinus lambertiana). These giant cones, of a species native to mountain slopes in California and Oregon, were the largest of any gymnosperm I had seen at that time, and I quickly discovered that herbaria were fascinating resources for studying plant diversity around the world.

Plant specimens capture important information on plant traits across species, continents, and centuries. With over 390 million specimens worldwide and becoming increasingly available online (500,000 specimens at Carnegie Museum alone), that’s a lot of potential information! We found that measurements using herbarium specimens strongly correlate to those measured in the field, including two leaf traits and one stem trait.

Years later as a graduate student interested in plant functional ecology, I was reminded of the diversity contained within herbaria, but learned that herbarium specimens were rarely used to study plant functional traits. Functional traits are characteristics that provide ecologists with information about growth, reproduction, or survival strategies, and in plants they are often measured using living tissue. For example, three commonly measured functional traits are specific leaf area, wood density, and leaf thickness. Specific leaf area (equal to the fresh area of a leaf divided by its dry mass) indicates how much dry mass plants invest in their leaves, a factor coordinated with their rate of photosynthesis. More specifically, plant photosynthetic rates tend to increase the bigger leaves get relative to their dry mass. On the other hand, wood density is used to understand carbon storage, which is important for studying carbon sequestration and climate change. Leaf thickness can help understand leaf thermoregulation, herbivory, and gas exchange. Currently, it’s unclear if herbarium specimens can provide reasonable estimates of these traits, but if so herbaria can vastly expand our understanding of plant functional diversity.

Recently, I teamed up with scientists Jessica Rodriguez and Dr. Mason Heberling (Assistant Curator of Botany at Carnegie Museum of Natural History) to understand if and to what extent herbarium specimens could be used as proxies for functional traits collected from fresh plant tissues. In our study just published in the American Journal of Botany, we found that herbarium specimens can provide accurate estimates of specific leaf area, branch wood density, and leaf thickness. Although drying plant tissues may lead to some inaccuracies in functional traits that are typically measured using fresh tissues, our study suggests the dead, dry, flat plants I once considered uninteresting could rapidly advance what scientists know about plant functional diversity. Importantly, our research highlights herbaria as rich sources of functional trait data with the potential to accelerate the study of important ecological processes like species responses to climate change.

Timothy M. Perez, Ph.D. is a postdoctoral scholar at the University of British Columbia whose research focuses on plant heat tolerance and the conservation of plants in the tropics.

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From Collector to Director

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Figure 1: CM 50625 – Rugosa Coral. Collected by M. Graham Netting in 1912.   Coral body shape has a radial symmetry.

In 1912, eight-year-old M. Graham Netting unearthed 13 coral fossils within the city limits of Louisville, Kentucky.  Later, as a 22-year-old Pitt student, he donated them to the Carnegie Museum of Natural History (Figure 1).   When the Great Depression cut short his graduate studies at the University of Michigan in 1929, he returned to the museum as Assistant Curator of Herpetology, and worked his way up to Curator in 1932.   In 1954, six months before turning 50, he was appointed Director of the Carnegie Museum of Natural History.   Along the way, the Wilkinsburg native left an astonishing legacy that includes a steady growth in scientific collections, numerous wildlife dioramas in the Halls of Wildlife, and a mid-Appalachian field research station, Powdermill Nature Reserve.  Upon his retirement in 1975, the Post-Gazette noted, “Long before it was “in,” Netting saw pollution of the air and water ravaging the land.”

Albert Kollar, Collection Manager of the of Section of Invertebrate Paleontology, re-discovered young Graham Netting’s horn corals while working on a multiyear review of the Bayet Collection.  Netting’s label note did not provide any evidence for the stratigraphic unit that he collected from, but more on that later.

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Figure 2: Carnegie Museum of Natural History exhibit reconstruction of an Early to Middle Devonian reef, 375 – 390 MYA.  The reef shows Rugosa and Tabulate corals, a spiny trilobite about 18 inches in length and several straight cephalopods.   Coral tentacles (shown in white) are illustrated in feeding mode.  Both Rugosa and Tabulate corals went extinct at the end of the Permian Period.

Rugose corals are often called horn corals because many species have a horn shape.  Horn corals attach to the sea floor by way of a sticky tentacle that protrudes from the base or curved end of the animal.  Other invertebrate animals, such as brachiopods, attached in this position are described as sessile.  The coral animal or “polyp” built its skeleton from calcium carbonate, a mineral formed from Bicarbonate and Calcium ions in seawater.  The polyp tentacles or feeding polyp extend out from the top of the basic body for feeding (Figure 2).  When the animal died, its soft tissues would have decayed and left behind the external hard mineral skeleton that fossilized.

Netting’s Louisville coral specimens are fossilized in a different way than similar corals from the nearby Falls of the Ohio middle Devonian fossil beds.  His corals are lighter and fragile to the touch, conditions which gave Albert reason to compare Netting’s fossils to similar invertebrate paleontology corals from strata within the Louisville area.  Sometime during or after burial, these horn coral skeletons were replaced by silica or quartz, a process known as silicification. The mineral silica can saturate a column of seawater when the seabed is overwhelmed with a large population of sponges.  Sponge skeletons are composed of silica and when they die silica is added to a column or more of seawater.  Volcanic eruptions eject silica into the atmosphere that eventually settles into the sea.  Again potentially adding higher amounts of silica.  Whatever the cause, Albert believes Netting’s corals were collected from the fossiliferous Middle Devonian age Jeffersonville Limestone, where the “lower foot of a “conglomerate” of reworked silicified Louisville Limestone” of Upper Silurian age is known to occur with silicified coral fossils (Conkin and Conkin, 1972).

Horn and Tabulate corals thrived in shallow seas forming diversified ecological reefs from about the late Silurian Period to the beginning of the Late Devonian epoch. During the Middle Devonian epoch roughly 400 Ma to 390 Ma years ago, reefs formed in central New York, southern Ontario, central Ohio, central Iowa, western Alberta, Canada, western Australia, and in Eifel, Germany.

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Figure 3:  Paleogeographic Map of the Middle Devonian Period – Kentucky is well south of the equator.

Louisville, during the Devonian Period, was centered in the southern hemisphere about 40 degrees south of the equator. Because of plate tectonics, the coral beds of Louisville would travel 5,500 miles over the next 390 million years to their present-day location of 38 degrees north (Figure 3). Today, fossil outcrops in the city limits of Louisville are difficult to find.

Figure 4: Graham Netting in his twenties.

When Netting retired as Director of Carnegie Museum of Natural History, he moved to a modest house next to Powdermill Nature Reserve.   A seat was saved for him each Sunday at the reserve’s weekly nature talk.  In 1996, he passed away.  Steve Rogers, Collections Manager for the Section of Birds, recalls sipping fresh lemonade on Netting’s back porch in 1981.   According to Rogers, Netting was reflective and humble.   The fossil collector who became a museum director had a habit of rubbing his chin while listening to someone speak.   When asked about his legacy, Rogers replied, “He was more instrumental in forming Powdermill than anyone.  He had an amazing ability to be a part of a team that got things done.”

Figure 5: Graham Netting at Retirement in 1975.

As Netting prepared to step down as director in 1975, he said, “These great collections are a natural resource to answer questions about the life of the world.” On a recent day, I saw two children jumping up and down in front of the Glacier Bear diorama in Hall of North American Wildlife on a family visit to the museum.   When one of the children asked, “what’s a diorama?” I thought about Graham Netting, smiled, and encouraged their engagement with the life of the world.

Many thanks to Xianghua Sun, Carnegie Museum Library Manager, Marie Corrado, Carnegie Museum Library Clerk, Stephen Rogers, Collections Manager for the Section of Birds, and John Wenzel, Director of Powdermill Nature Reserve for help researching this post.  

Joann Wilson is an Interpreter in the Education Department at Carnegie Museum of Natural History and Albert Kollar is Collections Manager for the Section of Invertebrate Paleontology. Museum employees are encouraged to blog about their unique experiences and knowledge gained from working at the museum.

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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.

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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 28th, 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 125th 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 1st 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
Carnegie Music Hall
Fig. 7

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 8th 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.

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