Biomedical Ephemera, or: A Frog for Your Boils

Nine-Banded Armadillo (Dasypus novemcinctus)

Did you know that the nine-banded armadillo (and a few of its Dasypus cousins) gives birth to identical quadruplets in almost every litter? Shortly after the zygote implants in the uterus, it splits into four (or occasionally three or five) separate embryos, each of which develop their own independent placenta. This means that, unlike in identical human fetuses, blood and nutrients are not shared, and the death of one fetus is unlikely to affect the survival of the others. After the pups are born, they remain in the burrow for approximately three months, and over the next year of their life, slowly wander farther and farther away from their place of birth.

As nine-banded armadillos have few natural predators in their Northern range, this highly effective reproduction strategy means that one female will often produce upwards of 50+ offspring in her relatively short lifetime. Those offspring have been expanding the armadillo’s known range for the past several decades. However, as armadillos are poor at thermoregulation, they’ve just about reached the limit of the area that they can survive in - any farther north, and they would not be able to survive the longer winters.

Images:

Top: Tatusia novem cincta [now Dasypus novemcinctus] - The Nine-Banded Armadillo. From Biologia Centrali-Americana. F. Ducane Godman and Osbert Salvin, 1918.

Bottom: Fetal Nine-banded Armadillo Pups. The American Journal of Anatomy. Vol. III, 1900-1901. “Enamel in the teeth of an edantate.” A. M. Spurgin.

compendium-of-beasts:

O Tatú - ilustração do livro “Duas Viagens ao Brasil” de Hans Staden (1557)

(Armadillo woodcut by Hans Staden)

compendium-of-beasts

Left: Armadillo Genus Alterum Clusii - “Armadillo, alternate genus”
Right: Armadillo siue Aiatochtli - “Armadillo or Gourd Rabbit [from Nahuatl language]”

All genus of armadillo have armored scutes that protect them from predators when they roll up, but the hardness and organization of those scutes varies. Because of this armor, the animals tend to be fairly slow. The denseness means that they’re also not naturally buoyant - however, the armadillo family has a counter for this! They inhale lots of air and expand their abdomen to twice the natural size, as well as being able to hold their breath for several minutes.

Ground armadillo has the dubious honor of being the only syphilis “cure” that you can contract Mycobacterium leprae from while preparing it. While I doubt Southerners are trying to cure syphilis with the armadillos they contact, it’s worth noting that over 70% of the leprosy cases in the Southern United States in the past two decades are thought to have armadillo-based origins.

A Description of the Nature of Four-Footed Beasts; With Their Figures Engraven in Brass. Joannes Jonstonus, 1655.

libcudl.colorado.edu

Do you have any armadillos in your natural history yet? — Asked by Anonymous

Yep! I have a few: Armadillo

I think armadillos are cool, though, so I’ll throw another up in a few.

heracliteanfire:

t-s-k-b: timtimtim: readyorknot: (via forbiddenalleys, unnaturalist)

unnaturalist

Giant Ant-Eater, Duck-Bill, Scaly Ant-Eater [Pangolin], Bristly Armadillo, Three-Toed Sloth

These are just awesome animals, all on one plate. How could I not post it? The Bristly Armadillo is listed as Dasypus setosus, but is now known as Euphractus sexcinctus, the Six-Banded Armadillo.

Natural History of the Animal Kingdom, for use of Young People. W. F. Kirby, 1889.

Comparison between Megatherium and Modern-Day Sloths

The armadillos are part of the same infraclass as the anteaters and sloths: Xenarthra.

The giant ground sloth Megatherium wasn’t a direct ancestor to the sloths we know today, much as Neandertals weren’t direct ancestors of humans. The other ground sloths (that weren’t nearly as huge) were much more closely related than Megatherium.

Or, at least they were more closely related to the two-toed sloth. Despite looking incredibly similar, the two-toed and three-toed sloths are actually not as closely related as one might think, and are actually an amazing example of convergent evolution. We know that the three-toed sloths are part of the same family as two-toed sloths, but their exact ancestry is almost completely unknown.

The pictorial museum of animated nature. v.1. Joseph B. Holder, 1904.

Six-Banded Armadillo, Tatouay, Truncated Clamyphore of Chili

The “Truncated Clamyphore of Chili” is what we now know as the pink fairy armadillo, and the tatouay is also known as the Greater Naked-Tailed Armadillo.

These are all South American armadillos. The one North American armadillo (the nine-banded) is the coolest one, in my opinion. They always have identical quadruplets, because shortly after fertilization, the egg splits into four. Basically, it’s exactly the same thing that happens in humans when identical twins are formed, but each half splits again. They’re the only mammals that reliably manifest this trait, called polyembryony.

The Animal Kingdom, Arranged According to its Organization. Serving as a Foundation for the Natural History of Animals and an Introduction to Comparative Anatomy. Baron Cuvier, 1837.

Cuvier Day

Pangolin, Armadillo, Sloth lovin’ on a branch, Armadillo

Baron Cuvier described and analyzed a massive fossil found in Paraguay. By analyzing the skull and structure of the bones, Cuvier determined that not only was this an extinct animal, it was a giant sloth. This was one of the first species he used to demonstrate extinction.