mammalogy

Word of the day triple play: PLANTIGRADE, DIGITIGRADE, UNGULIGRADE

Three forms of terrestrial mammal locomotion:

PLANTIGRADE: “sole walking”–animals walk by “planting” the full soles of their feet on the ground

DIGITIGRADE: “finger/toe walking”–animals walk with all or most of the length of their toes (“digits”), but not the full soles of their feet

UNGULIGRADE: “hoof walking”–animals walk on only their nails, usually hooves (as in “ungulates”)

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I joined @sealinefox on a Tule Elk Tracking trip, and we saw over 200 Tule Elk!
I learned so much, starting with the fact that Tule Elk are a subspecies of elk found only in California which were thought to have been hunted to extinction in the 1870s. A single breeding pair was discovered in the tule marshes of the San Joaquin Valley and conservation measures were implemented to protect the them. Today, there are over 4,000 wild Tule Elk in California, yet most of the public are still unaware of their existence.

I’m not sure which is the more remarkable specimen in this drawer. On the one hand, you have a very lightly-colored bear pelt that appears to be some sort of unusual Brown Bear (Ursus arctos). This light-tan face coloration mixed with medium brown body and limb fur is not very common, so we are lucky to have such a rare specimen. On the other hand, this drawer also contains Pangolins (family Manidae), every species of which currently faces serous threats due to hunting, trafficking, and habitat loss. This drawer truly holds mammal division treasures!

Photo credit: Ash Boudrie

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SIZING ALASKA’S MASKED SHREWS - Lathrop High School Senior Kelly May is headed to the National Junior Science & Humanities Symposium in Ohio this month with a research project refuting an earlier study on the effects of climate change on Alaska’s shrews. For this year’s Alaska Statewide High School Science Symposium (ASHSSS), May repeated a study published in 2005 using masked shrew specimens housed at the University of Alaska Museum of the North.

The original study, which concluded that shrews in Alaska are getting larger, was based entirely on data downloaded from the museum’s online database. The authors were not able to inspect each specimen. May believed that not accounting for age in the original research may have biased the results, so he tracked down each of the 650 specimens used in the original study.

Each shrew species has a unique tooth pattern. Since Alaska’s shrews can be difficult to identify, May first confirmed the specimens were the correct species (Sorex cinereus). Determining the age involved looking at the degree of wear on their teeth. Shrews do not hibernate and are active year round but they rarely live more than 15 months. Adults that survive a winter show significant tooth wear, while shrews born in the spring do not.

May learned that young shrews are significantly smaller than overwintered adults and that overwintered females are bigger than overwintered males. In contrast to previously published claims, this means that age and sex both need to be accounted for in studies of body size in shrews, according to the museum’s curator of mammals, Link Olson.

By analyzing juvenile and adult specimens separately and accounting for sex, May found that individual shrews are actually getting smaller but that more are surviving the winter, meaning that the proportion of (larger-bodied) adults in a given population is increasing. So although the two studies reached seemingly similar conclusions, May’s results shed new light on the underlying mechanism:  shrews aren’t growing to a larger body size, they’re just surviving winters better.

In June, May will travel to Philadelphia to present his research at the annual meeting of the American Society of Mammalogists. May plans to attend UAF in the fall.

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We answer your questions regarding anything from Dinosaurs, to modern animals, to evolution! Leave a comment!, you’ll be featured an upcoming video!

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A few of our favorite moments from the camera traps in Peru - the first captures the incredibly rare and elusive short-eared dog (Atelocynus microtis) making off with a massive fruit in its jaws (and it’s the first time this animal has been documented in this particular area!), and the second series shows a curious ocelot (Leopardus pardalis) in the middle of an early-morning prowl. 

Camera traps such as these provide untold insights on the biodiversity of an area. It may take a person years to report any solid evidence of these types of animals in a studied environment due to the difficulties of tracking creatures that have senses finely attuned to our presence in their territories. One of my favorite parts of being in Peru was simply knowing I was in a place inhabited by these magnificent species, despite the fact I would probably never get the chance to see them. 

To learn more about how mammalogists conduct surveys of these areas, check out our latest video checking out the bats of this region

.gifs by Tom McNamara!

Yesterday was an historic day for the bison.  President Obama signed a law making the bison the country’s first national mammal. Read a story from the New York Times.

Bison once numbered in the tens of millions in North America but, slaughtered for their meat and hides, the population was down to about 1,000 animals by the 1880s. Today, these animals thrive in part due to President Theodore Roosevelt’s efforts. As president, Roosevelt, who had witnessed the bison decline firsthand while living as a rancher in what is now North Dakota, created two big game preserves to save the buffalo from extinction: Montana’s National Bison Range and Oklahoma’s Wichita Game Preserve, where, in 1907, 15 bison bred at New York’s Bronx Zoo were released with a view to eventually repopulating the prairie. This and subsequent efforts brought the bison back from the brink of extinction.

Learn more about bison in this video:

Image: Bison diorama, AMNH/D.Finnin

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Scales, Feathers and Hair Have a Common Ancestor

by NICHOLAS ST. FLEUR

Reptiles have scales. Birds have feathers. Mammals have hair.
How did we get them?

For a long time scientists thought the spikes, plumage and fur characteristic of these groups originated independently of each other. But a study published Friday suggests that they all evolved from a common ancestor some 320 million years ago.

This ancient reptilian creature — which gave rise to dinosaurs, birds and mammals — is thought to have been covered in scale-like structures. What that creature looked like is not exactly known, but the scales on its skin developed from structures called placodes — tiny bumps of thick tissue found on the surface of developing embryos.

Scientists had previously found placodes on the embryos of birds and mammals, where they develop into feathers and hairs, but had never found the spots on a reptilian embryo before. The apparent lack of placodes in present-day reptiles fueled controversy about how these features first formed…

(read more: NY Times)

photographs by Nicolas Di-Poï & Michel C. Milinkovitch

My study buddy!

Study Finds Relationship Between Glyptodonts, Modern Armadillos

New research using a novel technique to recover ancient DNA reveals that the evolutionary history of glyptodonts—huge, armored mammals that went extinct in the Americas at the end of the last ice age—is unexpectedly brief.

The work, published this week in the journal Current Biology by an international team of researchers, confirms that glyptodonts likely originated less than 35 million years ago from ancestors within lineages leading directly to one of the modern armadillo families.

Numerous species of glyptodonts lived in dense forests, open grasslands, and a variety of other ecosystems, occupying a range that stretched from what is now the southern part of the United States to the Patagonia region of South America.

“Although their disappearance has been blamed on human depredation as well as climate change, some species persisted into the early part of the modern epoch, long after the disappearance of mammoths and saber-toothed cats,“ saidRoss D.E. MacPhee, an author on the study and curator in the Museum’s Department of Mammalogy. "Like the loss of giant ground sloths, mastodons, and dozens of other remarkable mammalian species, the precise cause of the New World megafaunal extinctions remains uncertain.”

Although scientists including Charles Darwin collected partial remains of glyptodonts in the early 19th century, at first nobody knew what kind of mammal they represented. It was eventually accepted that glyptodonts must be related in some way to armadillos, the only other New World mammals to develop a protective bony shell. However, because of the many physical differences between these two groups, most paleontologists have held the view that they must have separated very early in their evolutionary history.

To try and clarify this poorly understood history, researchers Frédéric Delsuc of the French National Center for Scientific Research at the University of Montpellier and Hendrik Poinar of McMaster University worked alongside MacPhee to learn what genetic information on these ancient armored animals could reveal.

As is often the case in ancient DNA investigations, fossil genomic material is poorly preserved, and only one sample worked—a carapace fragment of an undetermined species of Doedicurus, a gigantic glyptodont that lived until about 10,000 years ago. Using a novel approach to recover genetic information from ancient specimens, the team successfully assembled the complete mitochondrial genome of Doedicurus and compared it to that of all modern xenarthrans, a group of mammals including armadillos, sloths, and anteaters.

The researchers found that instead of representing a very early, independent branch of armored xenarthrans, glyptodonts likely had a much later origin, from ancestors within lineages leading to the modern armadillo family Chlamyphoridae.

More surprising still, the study finds that the closest relatives of glyptodonts—some species of which may have weighed 2 tons or more—include not only the giant armadillo (Priodontes maximus), which can weigh up to 25 pounds, but also the 4-ounce pink fairy armadillo, or pichiciego (Chlamyphorus truncatus).

“Contrary to what is generally assumed about the distinctiveness of glyptodonts, our analyses indicate that they originated only some 35 million years ago, well within the armadillo radiation,” Delsuc said. “Taxonomically, they should be regarded as no more than another subfamily of armadillos, which we can call Glyptodontinae.”

This post was originally published on the Museum blog. 

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Whale and dolphin intelligence documentary.
Originally aired in the early nineties. Both wild and captive animals. Also contains a small section on Navy dolphins.

This was made by Bernd Wursig, Professor of Marine Mammalogy, Director of the Marine Mammal Research Program, and Co-Director of the Institute of Marine Life Sciences at Texas A&M University, and it is still relevant today.