#cynodonts

[boobookittenartblog]

Paleofauna of Sitio Niemeyer. Santa Maria Formation, Brazil.

Triassic period. Landscape with Hyperodapedon sajuanensis, sauropodomorphos basaic, lagerpetids, and cynodonts.

Artwork by Caetano Soares

[cellulosaurus]

Anguirus, the traversodontid cynodont

Got the idea because when that new Spicomellus paper came out and everyone was “omg real life anguirus omg omg” and I could not stop thinking about my beloved Protuberum that has been ignored for too long

It was a weird weird cynodont with bumps on its ribs, similar to Spicomellus, although unlike it these weren’t osteoderms that fused to the bone but directly outgrowth of the ribs, somethting completely unique. And since Anguirus has a face not too dissimilar to that of cynognathians (the group of cynodonts that include traversodontids) I decided to take a crack at it.

They are sorta similar if you squint really hard (Left image modified Reichel et al. 2009, right from the production of Destroy All Monsters)

[dromaeosaurid]

"The advanced paramammals, the theraspids, evolved some 50 million years after the early flesh eaters. Giant lumbering plant eaters such as Moschops were forerunners of dicynodonts such as Lystrosaurus and Dinodontosaurus. Fierce flesh eaters such as Titanosuchus were ancestors of both the cynodonts (Thrinaxodon and Cynognathus) and the bauriamorphs (Bauria). Furry, warm-blooded flesh eaters, these were only a step away from being mammals. Morganucodon, the first true mammal, evolved around 200 million years ago."

From "The Evolution of the Mammals" (1978), by L.B. Halstead. This illustration by Enzo Carretti.

[mineralsrocksandfossiltalks]

Fossil Friday: Cynognathus

Cynognathus crateronotus has been a pretty big deal in paleontology since the late 1880's but was brought to the public's attention by this gem:

(If you are somehow not aware, this is BBC's 1999 Walking with Dinosaurs. If you haven't seen it, go watch it now. It's fantastic).

While the show depicted Cynognathus living alongside Postosuchus and Coelophysis, it actually hasn't been found in North America where the pseudosuchian and dinosaur have been found. Those two are also Late Triassic animals while Cynognathus is a middle Triassic animal.

Cynognathus was first discovered by Harry Seeley in southern Africa in 1889. He also named the genus and type species. The name Cynognathus means "dog jaw" in reference to the very mammalian -looking jaw.

Cynognathus was part of the cynodont family of early therapsids, the clade which mammals belong to. It had many characteristics in common with mammals including differentiated teeth,

a secondary palate which indicates it could breathe and swallow simultaneously, a lack of belly ribs which might indicate the presence of a diaphragm and concentrations of pits and canals on the snout which could support whiskers.

However, it still retained some primitive features like multiple lower jaw bones, and semi-sprawled legs (however, recent studies of living mammals indicate that only certain groups of mammals have the upright posture we've come to associate with mammals).

Cynognathus was one of the fossils used as a piece of evidence for continental drift by Alfred Wegener as it has been found in southern Africa, Argentina, and Antarctica.

Tune in Sunday at 6pm for live stream discussion with colleagues as we talk about a large sauropodomorph from China. We will also answer a handful of questions at the end, some come prepared and we may choose you! Fossilize you later!

[dougdimmadodo]

May’s Fossil of the Month - Thrinaxodon (Thrinaxodon liorhinus)

Family: Thrinaxodon Family (Thrinaxodontidae)

Time Period: Early Triassic (251-247 Million Years Ago) 

At the end of the Permian period around 251 million years ago, the earth experienced the most extreme extinction event in its history (known as the Permian-Triassic Extinction Event or “The Great Dying”,) in which some 70% of terrestrial species and 81% of marine species were driven to extinction. As such, the period immediately following the Permian, the early Triassic, was a period of slow recovery as the descendants of the few survivors of the Great Dying began to adapt and diversify to fill the ecological niches left empty by the extinction of their previous occupants. Thrinaxodon liorhinus was one such survivor; a small (roughly 50cm/1.6 feet in length) species of cynodont synapsid (making it a close relative of mammals, but not a mammal itself), it inhabited what is now southern Africa and northern Antarctica (which were fused as part of a single landmass at the time) in the period immediately following the great dying, and was seemingly among the largest and most common carnivores of its time. Thrinaxodon’s survival was likely enabled at least in part due to its lifestyle; the discovery of individuals fossilized in the remains of burrows show that Thrinaxodon, like many similarly-sized mammals today, was a burrower, and the presence of distinct divisions on its spine to aid in flexibility suggests that, like many burrowing mammals and reptiles today, it may have possessed the ability to travel deeper underground and undergo hibernation or aestivation in order to endure prolonged periods of harsh weather conditions and resource scarcity. In life Thrinaxodon would have likely appeared somewhere between a large lizard and a small dog, with its leg bones and joints suggesting that it stood in a “semi-sprawling” posture mid-way between the belly-to-the-ground sprawling of most lizards and the elevated posture of most mammals, while its dog-like skull and sharp-tipped teeth (including prominent canines on both the upper and lower jaw) suggest that it was likely carnivorous, feeding on insects and/or smaller vertebrates. The discovery of the remains of several Thrinaxodon individuals, sometimes including juveniles, preserved in close proximity to one another suggests that members of this species likely provided parental care and may have also been social, and one unusual but extremely famous fossil burrow containing both an adult Thrinaxodon and an injured Broomistega putterilli (a small species of superficially salamander-like amphibian) showing puncture wounds from teeth too large to belong to the burrow’s owner suggests that, like the Gopher Tortoise and Giant Armadillo today, Thrinaxodon may have been a habitat engineer, with its burrows providing shelter for other species of animal (although it is also possible that the Broomistega had been washed into the burrow during a flood that killed both animals, or that the Thrinaxodon had stolen the injured Broomistega from the larger carnivore that wounded it.)

--------------------------------------------------------------------------  

Image Sources:  https://commons.wikimedia.org/wiki/File:Thrinaxodon_liorhinus_BP_1_7199.jpg

and

https://www.pbs.org/video/the-oddest-couple-in-the-fossil-record-rcehau/

[antiqueanimals]

The World of Dinosaurs. Written by L. B. Halstead. 1979.

Internet Archive

[volley-ball-101]

OFFICAL list of sexy people traits that only the SEXIEST people posses. Not up for discussion.

[vickysaurus]

Thrinaxodon, a cynodont! I'm doing paleoart of three synapsid relatives of the mammals as a kind of bonus page to the Humans and our Cousins project I did. The gap between monotremes and sauropsids just felt too big, and I wanted to try my hand at paleoart anyway. These lived about 250 million years ago in the early Triassic, just after the Permian extinction that wiped out most synapsids, and were carnivores about the size of a fox. While most of their features would have been mammalian like I depicted them, I unfortunately made a mistake I had already committed to before I discovered my initial research was wrong: they probably did not have pinnae (external ear shapes). The position on the back of the lower jaw, however, is where a cynodont's ear would be. In fact that's where most Tetrapods that aren't mammals keep their ears.