Carnegie Museum of Natural History

One of the Four Carnegie Museums of Pittsburgh

mammals

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Early Bats: Ancient Origins of a Halloween Icon

Specimen Carnegie Museum (CM) 62641, the holotypic, or name-bearing, right dentary (lower jaw bone) of the tiny fossil bat Honrovits tsuwape in lingual (= internal) view, still partially encased in ~50-million-year-old rock of the Wind River Formation of west-central Wyoming. Note the length of the scale bar, only 1 cm (less than half an inch)!

Did you know that bats have been around for at least 55 million years? In 1992, several fossils in the Carnegie Museum of Natural History collection, including the lower jaw bone shown above, were described as representing a new genus and species of ancient bat, Honrovits tsuwape—Shoshone for “bat” and “ghost,” respectively—by a team that included two former curators in the museum’s Section of Vertebrate Paleontology, Christopher Beard and Leonard Krishtalka, both now of the University of Kansas. Honrovits dates to the early part of the Eocene Epoch of the Cenozoic Era (the ‘Age of Mammals’), about 50 million years ago, and is a member of a now-extinct bat group called the Onychonycteridae.

Replica of a beautifully preserved fossil skeleton of Onychonycteris finneyi, a close relative of Carnegie Museum of Natural History’s own Eocene-aged bat Honrovits tsuwape, on display at Fossil Butte National Monument in Wyoming. Photo by Matthew Dillon.

Interestingly, Honrovits shares dental characteristics with a mammal group known as insectivores, which includes today’s hedgehogs, shrews, and moles, and in that sense, it differs from the condition in most other bats. However, bat teeth possess distinctive diagnostic features, so although Honrovits is known only from a few tooth-bearing jaw bones and a skull fragment, there’s no doubt that the diminutive beast was indeed an early bat. The fragmentary nature of its fossils means that we don’t know for sure what Honrovits looked like in life, though it’s a good bet that it bore a close resemblance to other onychonycterid bats, such as Onychonycteris finneyi, which is known from exquisitely preserved skeletons (such as the one shown above).

Flesh reconstruction of the ~50-million-year-old bat Onychonycteris finneyi. There’s an excellent chance that Honrovits tsuwape would have looked like this. Art by Nobu Tamura.

The incompleteness of the Honrovits fossils is, unfortunately, the norm rather than the exception when it comes to prehistoric bats. Fossils of these creatures are exceedingly rare because most bats have very small, light skeletons and achieve their greatest diversity and abundance in areas that have low potential for fossil preservation, such as tropical forests. Occasionally, complete skeletons such as those of Onychonycteris are found, but not nearly as often as fragments.

So, this autumn, if you happen to catch a glimpse of a bat silhouetted against the evening sky, acrobatically wheeling and plunging in pursuit of flying insects, pause and reflect on the history of these extraordinary flying mammals whose ancestry dates nearly to the time of the dinosaurs.

Linsly Church is a Curatorial Assistant 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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Sympathy for the Devil

Bats and devils are among the most popular topics associated with Hallowe’en.  Of course, the research collection in the Section of Mammals has worldwide examples of bats species, but we don’t find them scary and we think about bats and their vital ecological roles all year long.  Perhaps more mysterious and less well-known are the two Devil specimens stored among the wombats, kangaroos, and koalas in our collection.  Even school children have heard about *our* kind of devils.  Yes, the Tasmanian devil (Sarcophilus harrisii) is a marsupial – a pouched mammal, like our opossum – that is found only on the island of Tasmania, located some 140 miles off the southeast coast of Australia.  Fossil evidence tells us that it once lived on the Australian mainland, but it may have been wiped out on the continent by the introduction of the Dingo, Australia’s legendary wild dog.

photograph of Tasmanian devil

The Tasmanian devil is a stocky mammal with short legs, short black fur and a distinctive white throat patch. Its head is noticeably large for the size of the body. An adult male may weigh up to 20 lbs. They are nocturnal with a good sense of sight, smell, and touch. Devils are known to cover significant distances nightly, in search of carrion or prey. They can move surprisingly fast and seem to enjoy swimming. In the wild, individuals can live between five and seven years, but many die within the first year of birth. Although it is the largest living marsupial carnivore, the Tasmanian devil is predominantly a scavenger.

Tasmanian devil skull

A close look at the skull shows evidence of space on the side of the head for large jaw muscles. For its size, the Tasmanian devil has the strongest bite force of any mammal – more powerful than even a hyena! With the large masseter muscles and especially large molars, it can easily crush bone. In fact, devils are such efficient carrion-eaters that they willingly consume an entire carcass, including the fur.

Although this animal gained a reputation for having a bad disposition, it is speculated that this impression was derived from the poor conditions it was kept in when first captured for observations. Since then, it sometimes has been kept humanely as a pet and been found to be much friendlier than initially reported. Tasmanian devils do not seek each other’s company except during the mating period. However, they often come together to feed on a dead animal, where vocalizations and as many as nineteen different behavioral cues are used for communication. These communal gatherings are characterized by aggression and loud sounds, described as “frequent growling” and “blood-curdling screams”!

In 1996, a sad chapter began in the existence of the Tasmanian devil. A deadly infectious cancer called devil facial tumor disease, began to spread within the population. In 2012, the Australian government transferred 30 disease-free individuals to tiny Maria Island off the coast of Tasmania, in what was called ‘island insurance’, while researchers worked on perfecting a vaccine. By 2017, the disease had led to a 90% extinction rate on Tasmania. In hopeful news, by 2019 there were indications that surviving individuals’ immune systems may be undergoing modifications to fight the disease. In early September 2020, a consortium of conservation groups released 11 Tasmanian devils to a wildlife sanctuary in the state of New South Wales, placing the Tasmanian devil on the Australian mainland for the first time in more than 3000 years.  An additional 15 devils were released in early October and more releases are planned.

Currently, the Tasmanian devil is not extinct, but its recovery hangs in the balance. It would be tragic if we are left only with museum specimens and Taz, the Looney Tunes cartoon image, of this fascinating mammal.

Suzanne B. McLaren is the Collection Manager in the Section of Mammals at Carnegie Museum of Natural History. Museum employees are encouraged to share their unique experiences from working at the museum.

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Scientist Takeover: Mammals!

What is the largest mammal?

This is an easy one because it is not even close; the blue whale, which is also the largest animal to ever live on Earth, weighs around 100 tons (220,000 pounds) and is about 100 feet long. Females are typically larger than males. Despite their bulk, blue whales are filter feeders subsisting on krill, small crustaceans less than an inch in length.

In 1758, Carl Linnaeus gave the blue whale the Latin name Balaenoptera musculus. The first part, Balaenoptera, the genus name, means winged whale for its long, slender flippers; the second part, the species name, is thought to be a joke by Linnaeus because it is also the species name he gave to the house mouse, Mus musculus.

Here is the left mandible (lower jaw) of a blue whale on the second floor in the Carnegie Museum of Natural History. Notice that it dwarfs the adult polar bear behind it.

What is the smallest mammal?

This is harder than the largest one—the blue whale—because there are two mammals considered to be very close in weight: the Etruscan shrew with a Mediterranean and Asian distribution weighs in about 1.8 grams, which is less than the bumblebee bat from Thailand and Myanmar, weighing in around just 2 grams, but the shrew is longer than the bat. Remember there are 28 grams in one ounce and 2 grams is the weight of one paperclip!

This is the smallest North American mammal, the American pygmy shrew. This example, from the research collections of the Carnegie Museum of Natural History, is under four inches in total length.

What is the fastest land mammal?

The cheetah is hands down the fastest, but it does not sustain speed over a great distance; the cheetah is a burst-predator with a chase lasting typically less than a minute. The cheetah goes from 0 to 60 miles per hour in about three seconds, which is what a good sports car can do! At top speed, the length of one stride is 21 feet and there are four strides per second.

Everything about the cheetah is built for speed and hunting. This view of a skull in the research collection of Carnegie Museum of Natural History shows enormous orbits for its large eyeballs providing keen vision and its very large nasal opening, which allows more oxygen to enter the lungs.

What is the slowest land mammal?

The name says it all…sloth! There are two types of sloths found in the tropics of Central America and northern South America, usually called three-toed and two-toed sloths. This is a misnomer as both types have three toes on their hindfeet; what differs is the number of fingers on the forefeet. So, they really should be called three- and two-fingered sloths. Both sloths live most of their lives in trees on a diet of leaves and move so slowly or so little that algae grow on their fur, providing camouflage. Of the two sloths, the three-digited one is smaller and slower.

This skin of a three-toed sloth from the research collection of the Carnegie Museum of Natural History shows a mammal built for hanging around in trees, with its long arms and hook-like claws on all four limbs.

What is the strongest mammal?

This is just a playful question. It usually isn’t one of the comparisons that scientists try to make.  However, the armored hero shrew seems like a good nominee. This shrew lives in the forested region of central Africa. Its spinal column is unique among mammals. The mid-portion is extremely modified with many interlocking bony tubercles that project forward and backward to fortify the spine. The exact purpose is unknown. However, it has been reported that a full-grown man could stand on the back of an armored shrew without harming the animal.

The skin and partial vertebral column of an armored hero shrew from the research collection of the Carnegie Museum of Natural History shows the beautifully intricate bony structure of the spinal column, which lies hidden inside of a perfectly normal looking long-haired shrew.

John Wible is Curator of the Section of Mammals and Sue McLaren is Collection Manager of the Section of Mammals at Carnegie Museum of Natural History. This post is part of Super Science Days: Scientist Takeover! 

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South American Hippo Habitat

two South American hippo toys

In the wake the groundbreaking exhibition, We Are Nature, museum educators increasingly recognize opportunities for existing exhibits to foster discussions of profound human impacts. Because of a recent research study published in Proceedings of the National Academy of Science, even these sturdy plastic components of the African Wildlife Play Table (above) can spark wide ranging discussions about the impacts of large animal relocations.

The research paper Introduced herbivores restore Late Pleistocene ecological functions, by ecologist Erick Lundgren (University of Technology, Sydney, Australia) and ten co-authors, documents the establishment and growth of a hippo population along a section of Columbia’s Magdalena River over the past three decades. The founding members of a population now estimated to include as many as 80 individuals were four hippos, three females and one male, acquired during the 1980s by notorious drug lord Pablo Escobar for a private zoo on his estate.

According to researchers, the population of Magdalena River hippos could grow to between 800 and 5,000 animals by the year 2050.

For a summary of the research and its implications by The New York Times science writer Asher Elbein, please visit “Pablo Escobar’s Hippos Fill a Hole Left Since Ice Age Extinctions.”

Patrick McShea works in the Education and Visitor Experience department of 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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How-to Draw a Squirrel

If Pittsburgh had an animal mascot, I think it would be a squirrel.  So, let’s draw a squirrel together.

Early naturalists, explorers, and scientists didn’t have cameras to take photos of the animals and plants that they saw.  Instead they would draw them so that they could show fellow scientists and the public what kinds of new species they discovered.

One of the many squirrels that live in our area is the gray squirrel.  Gray squirrels usually have a grayish or brownish back and a white belly.  Some gray squirrels are melanistic—that means that they’re all black—and we call them black squirrels, but they’re actually a gray squirrel.

Before we get started you might need to gather some supplies.  Use a pencil and eraser, just in case you make some mistakes (it’s okay to make a mistake).  Get some paper and a comfy spot to draw—make sure you cover your table to avoid making marks on it.  Don’t forget the colors!  I like colored pencils, but you can use markers, crayons, paint, or anything else to color with.

Here’s a tip: try out some ideas on scrap paper so that you know what works best for you.  Practice makes perfect!

Step 1: Shapes

Use some basic shapes—circles, triangles, squares, and lines—to make up the general shape of what you want to draw.  Use light pencil strokes so that they’ll be easy to erase later.

Try to keep all of your shapes balanced to one another—you don’t want your squirrel to have a huge head!

I started by drawing a big circle, like a boundary zone, to keep all of the other shapes from getting too big.  It doesn’t have to be a perfect circle; we can erase it later.

I also like to have a photo that I’ve taken or found online to use as a reference for what I’m drawing.

If you want to take it to the next level, you can also check out some anatomical and skeletal models of squirrels or other animals online to understand more about their muscle and bone structure.

Step 2: Silhouette

Next let’s connect our shapes so that we can have a good outline of our subject.  You can add eyes and some of the rough edges.  Try to zone out where your colors will change too—for instance the squirrel’s white belly will be different than its greyish brown back, so I’ll add a line to mark that.

We can also erase that boundary zone circle we made earlier, unless you want to add a colored background for your squirrel.

Let’s also give our squirrel a nut to eat.

Step 3: Details

Add more details.  Add some furriness to the body, add in details on the ears and face—including some whiskers, and make that tail really fluffy.  You can also erase some of those shapes we made in step 1 and feel free to make a few changes to balance it all out if you want to.

It’s also important in this step to know how detailed you want to be.  Remember: a smaller sketch doesn’t need as much detail, but a bigger sketch can have more.  Whatever you think looks best.

Step 4: Color

This step is optional, sometimes a black and white sketch can tell a great story.  However, if you have some time, then adding color to your drawing can also really bring it to life.

You can use crayons, markers, paint, or any other color tool you want.  It’s always a good idea to test your colors on a separate piece of paper to see if they’re right for you or to try out a mix of colors.  Squirrels that live in North America are usually brown, black, red, or gray, but there are very colorful squirrels in the tropics. Have fun with it!

Be proud of your sketches!  No one else could have made it the same way that you did.  By drawing and coloring plants, animals, and other nature you can sharpen your observation skills and gain a better appreciation for the beauty and uniqueness of all life.

Aaron Young is a museum educator on Carnegie Museum of Natural History’s Outreach team. 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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Groundhog Day 2020!

One of my favorite taxidermies in the Section of Mammals, Carnegie Museum of Natural History, is our groundhog with a malocclusion. Say what?

So, in dentistry, a malocclusion is the imperfect positioning of teeth when the jaws are closed, usually a cosmetic issue. If you are a rodent, like our groundhog, a malocclusion is not just cosmetic, but life threatening.

Rodents (including squirrels, beavers, rats, guinea pigs, and capybaras) are the most successful group of living mammals, accounting for about 40% of all species (2,500 out of 6,000). A key innovation that has led to their evolutionary success is their pair of enlarged upper and lower incisors that continue to grow during the life of the individual. Looking at a rat skull (below), you will notice that the incisors are enormous, especially compared to a molar tooth in the CT scan. When the upper and lower incisors occlude (that is, contact), over time they create a sharp, chisel-shaped cutting blade that is, for example, the reason a beaver can cut down a sizeable tree. Their incisors continue to grow and maintain that cutting blade. In contrast, your teeth don’t grow (nor do the molars of the rat or groundhog); in fact, they get smaller as they wear down.

If something goes awry with a rodent’s incisors such that the uppers and lowers get off kilter and don’t meet to create that cutting blade, the incisors will still continue to grow, and grow, and grow, as with our poor maloccluded groundhog. Ultimately, the animal will be unable to eat and starve to death. Ironic that the key innovation leading to the success of the rodent lineage can also be deadly for an individual on the rare occasion that things go wrong.

Rattus norvegicus, brown (Norway) rat, skull in lateral view (above) with sagittal section from CT scan (below).

John Wible, PhD, is the curator of the Section of Mammals at Carnegie Museum of Natural History. John’s research is focused on the tree of life of mammals, understanding the evolutionary relationships between living and extinct taxa, and how the mammalian fauna on Earth got to be the way it is today. He uses his expertise on the anatomy of living mammals to reconstruct the lifeways of extinct mammals. John lives with his wife and two sons in a house full of cats and rabbits in Ross Township.