#metatheria

[alphynix]

It's time for a little bit more recent PBS Eons work this week:

• The metatherian predator Arctodictis and the litoptern ungulate Thoatherium from "The Mystery of South America's False Horses"

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[biol525-mammalogy]

metatheria -> didelphimorphia -> didelphidae (new world opossum)

[obscurefossils]

Sulestes

Sulestes was a genus of deltatheroidean mammal from the Cretaceous Period. Its type species is S. karakshi. The known specimens were found in the Bissekty Formation, Kyzyl Kum desert, Uzbekistan. Sulestes was the first and currently only identified metatherian taxon from the Bissekty Formation.

Its autapomorphies include the first premolar's oblique orientation relative to the dentary, an asymmetrical third molar, the presence of a fourth non-vestigial molar, and a double-rooted first premolar.

Sulestes is known from its holotype, a left maxilla fragment, as well as referred specimens. These specimens were originally labelled under "Deltatherus" and "Marsasia" and consist of a right petrosal, right maxilla, two left maxilla fragments, left coronoid process, several right and left dentary fragments, and a few isolated teeth. Sulestes is recovered as the sister taxon to Deltatheroides and Deltatheridium within Deltatheroida. 

Citations: The original description paper, Nessov 1983, is not available online. Nessov and Russell 1994 (description); Averianov, Archibald, and Ekdale 2010 (referred material).

Wikipedia article: here

[robbie-roo]

Marsupials (overview)

Hello, desktop Tumblr it is time to talk about mammals again >:)

I can feel my roommate watching me over my shoulder...

also wow using grammerly on desktop is really annoying! but I can use titles???? woo!

I think I regret choosing desktop for this.... oh well! lets get into it

Ok so we left off talking about monotremes and I will have a post about their bones at some point I pinky swear I just need to figure out what I want to talk about. ok anyways today let's see what should we talk about hmm.... drumroll please.....

Metatheria!

So metatheria are the marsupials of the animal kingdom you've heard of a lot of them and I'm sure you know their calling card- pouches. but we are getting INTO it tonight guys heheheh

ok so some Latin facts- we know that protheria (monotremes) means 'first beast' but metatheria means "in-between beasts"

the first/oldest protheria we know about is the sinodelphys they are found mostly in Australia and South America due to a lack of placental mammals during the whole continental drift business.

ok so what makes a marsupial a marsupial? well let's get into a few relatively universal traits amongst them (remember folks nature doesn't read biology books so some of these are special or gone in certain groups)

so bones (BONES!!!!)

so the pelvic and jaw bones in a metathere are different than in eutheres (we will talk about them next teehee) they do not have a rounded angular process and it's instead spiky (here's a picture of a possum jaw for reference)

There are also extra openings in the back of the pallet and a smaller brain case their teeth are funky too! They have an extra set of incisors.

so I mentioned their funky pelvic bones but what I mean by that is their reproduction is wacko. so like monotremes they have a cloaca and not a vaginal and anal opening. this is why they're "in-between beasts" they have traits that are similar to both ends of the spectrum.

speaking of reproduction their cloaca is subdivided and they will hold eggs internally with a specialized membrane. this membrane surrounds the fetus more than an egg would with a floating placenta surrounding the fetus unlike in us this placenta isn't attached to a uterine horn. Their reproductive structure is also loopy... I'm not kidding look at this shit- this is a kangaroo reproductive structure

WEIRD! They have a pseudovaginal canal which is only there for birth and is part of the cloaca also keep an eye on that second uterus ill get into that more with kangaroos specifically

and it's only in females male reproductive structure is normal

their young are always born underdeveloped. they have an extended lactation period because of this with that special changing milk we mammals have that will deliver the perfect amount of nutrients needed.

so the babies are born super early but those ungrateful little turds have the immediate responsibility to get THEMSELVES into their mother's pouch. Mamma can't help you do everything little Joey.

I need to expand on this because it's fucking INSANE ok so like I said they are underdeveloped and I mean like VERY underdeveloped as in they do not have a full heart or brain yet!!!!! their lungs are just sacks and they don't have a jaw but they DO have a tongue and arms that they use to pull along their mother's hair to get to the milk. again- mama ain't helping you.

Ok i'm ending this here only because this is just general overview stuff and then I'm gonna get into specific species and families next staring with kangaroos :)

[extinctworld-ua]

Anachlysictis

Anachlysictis — рід вимерлих хижих ссавців з групи Sparassodonta, представник метатеріїв (група, що включає сумчастих та їхніх близьких родичів), котрі населяли Південну Америку протягом кайнозою. Типовий вид — Anachlysictis gracilis.

Повний текст на сайті "Вимерлий світ":

https://extinctworld.in.ua/anachlysictis/

[animalids]

Spotted-tail quoll (Dasyurus maculatus)

Photo by Caleb McElrea

[synapsidgirl]

UK just went into a lockdown today, I have a lot of not very well defined thoughts about it, so naturally, I'm doing some Thylacosmilus studies. Here's the first one done. He's either just yawning, or maybe it's a threat display. Yes, his ears aren't flattened against his head, but I based this on thylacines, tasmanian devils, and american opossums who didn't/don't seem to be flattening their ears as a part of their threat displays either. At least that's what it looks like to me in pictures and videos. Of course, thylacines, devils, and opossums aren't related to Thylacosmilus, but since the jaws-agape-ears-not-folded threat display seems to be quite common among modern metatherians across different genera, I've decided to go with this, rather than ears-folded-lips-in-a-snarl placental thing. And yes, something bit his ear. I don't know what it was, but it doesn't seem to bother him much. I feel like I could have added more loose tissue around the lower jaw, since the lips would be so substantial, but I quite like how this turned out anyway. Also, I used yawning bloodhounds and basset hounds as reference for the lips situation, since they're very gifted in the jowls departament.

[huxley-paleozoo]

Thylacosmilus

Scientific name: Thylacosmilus atrox Diet: Herbivorous mammals, with some supplemental fruit Projected natural lifespan: 20 years Length: 1.2 meters (4 feet) Weight: 80 kg (176 lbs) Locality: Northern Argentina; 9-3 Ma (Miocene-Pliocene) Exhibit: South America

About Thylacosmilus is one of the largest and last of the sparassodonts, a group of South American predators closely related to marsupials. It has two large saber-like teeth in the upper jaw - but unlike those of saber-toothed cats, they’re rooted far back in the skull. The lower jaw has a pair of flanges at the front that shield the saber teeth. Thylacosmilus has a relatively low bite force, instead using its powerful arms and neck to force prey into submission.

At Huxley Thylacosmilus can be found in the Cenozoic South America section. One of our younger Thylacosmilus is an ambassador animal - you can visit him at the Anning Paleontological Museum on weekends!

Notable Behavior We have three adult Thylacosmilus that we rotate through the exhibit areas. Although we gave them the opportunity to interact with each other, they did so rarely. A lot of times, when they see each other, they do what we think is a territorial display: they will open the jaws wide - up to almost 110 degrees! - and show off the saber teeth. They all use the same areas of their enclosures as a latrine, including where they mark territory.

Like the incisor teeth of rodents, the saber teeth of Thylacosmilus never stop growing through their life. In order to keep the teeth at a manageable size, we give them lots and lots of things to chew on, from durable rubber toys to rawhide and bones. They’re very good at destroying things.

Keeper Notes Have you ever been licked by a Thylacosmilus? They have huge tongues and they drool. A lot.