#sauropterygian

Artfight Attack #15

Featuring Thrasher by finchii and Onoclea by fernybiird!

🎨: The_trexdraw (Chubutinectes pictured)

New plesiosaur, Argentinonectes calafatensis, is described from a rather complete skeleton from Upper Cretaceous Patagonia. It helps shed light on the tail anatomy for these plesiosaurs.

Argentinonectes calafatensis (Ar-Gen-Teen-Oh-Neck-Tease | Cah-Lah-Fah-Ten-Sis) "Argentino Lake Swimmer from Calafate"

Paper here:

PDF here:

Nothosaurus

Repost! This one is from February 2025.

Irritator

Results from todays flocking paleostream

2: This pathetic little beast is a baby atopodentatus, which actually couldn’t bend their elbows, and after that I made this

Pencil portrait_Liopleurodon.

Pencils, 2022.

By Tas Dixon

Etymology: False Reptile 

First Described By: Münster, 1834 

Classification: Biota, Archaea, Proteoarchaeota, Asgardarchaeota, Eukaryota, Neokaryota, Scotokaryota, Opimoda, Podiata, Amorphea, Obazoa, Opisthokonta, Holozoa, Filozoa, Choanozoa, Animalia, Eumetazoa, Parahoxozoa, Bilateria, Nephrozoa, Deuterostomia, Chordata, Olfactores, Vertebrata, Craniata, Gnathostomata, Eugnathostomata, Osteichthyes, Sarcopterygii, Rhipidistia, Tetrapodomorpha, Eotetrapodiformes, Elpistostegalia, Stegocephalia, Tetrapoda, Reptiliomorpha, Amniota, Sauropsida, Eureptilia, Romeriida, Diapsida, Neodiapsida, Sauria, Archosauromorpha?, Archelosauria, Pantestudines, Sauropterygia, Eosauropterygia, Nothosauria, Nothosauridae, Nothosaurinae 

Referred Species: N. mirabilis, N. cristatus, N. cymatosauroides, N. edingerae, N. giganteus, N. haasi, N. jagisteus, N. marchicus, N. mirabilis, N. tchernovi, N. yangjuanensis, N. zhangi 

Time and Place: From 242 million years ago until 208 million years ago, from the Ladinian of the Middle Triassic through the earliest Rhaetian of the Late Triassic

Nothosaurus is known from all over Eurasia and North Africa, to the point that it’s pointless to list all the locations. Just assume that if it’s the Mid or Late Triassic of the Tethys Sea, Nothosaurus is there.

Physical Description: Nothosaurus is an iconic Triassic marine reptile - to the point that we had to include it, or else we would have violated some sort of rule of paleontology. Nothosaurus was about 4 meters long on average, but could reach up to 7 meters in length. It had a long, streamlined body, with a long neck and a long tail. Its head was narrow and filled with long and pointed teeth which interlocked together when the mouth closed, forming a tight trap. Its forelimbs were longer than its hind limbs, and all of its hands and feet had webbing between the long toes. In a lot of ways, it looked extremely similar to later marine reptiles to which it was closely related, like the Plesiosaurs and Pliosaurs, just with hands instead of proper flippers - however, current evidence indicates that the Plesiosaurs and Pliosaurs evolved from an ancestor of both groups, and Nothosaurus is just a Triassic offshoot. It had capabilities for diving in the water, though it also was still adapted for life on the shore. 

Diet: Nothosaurus primarily ate fish and other marine animals, including other marine reptiles. 

Behavior: Nothosaurus was semi-aquatic, spending a lot of its time both in the ocean and on land. On the beaches and shores it would rest and sleep, and then turn to the ocean for most of its everyday life. Diving for food would have been most of its daily activities, going after juvenile reptiles and large fish in the water and diving in order to reach it. It probably would have paddled with its webbed feet, and undulated its body to some extent to help propel forward. It may have been at least somewhat social, living in groups and colonizing the shores together before going for group dives for food. Interestingly enough, Nothosaurus was basically like a reptilian seal, coming up to shore to rest and sit with its relatives. Whether or not they would have given birth to live young is uncertain; while their close relatives, the Plesiosaurs, did; they retained enough land adaptations to allow them to lay eggs on the shore. More research as to their physiology is needed in order to determine that aspect of their life history. Trackways have been attributed to Nothosaurus, which may show that they rowed their paddles on the sea bed to shake up small animals trapped underneath; this would have allowed Nothosaurus to capture the invertebrates between its long teeth and hold onto them so they could not escape. 

Ecosystem: Nothosaurus lived throughout the early Tethys sea, and was a common feature in many communities throughout this growing body of water during the Middle and Late Triassic. It would have stuck to the coasts for the most part, but still ventured out into deep and open water. As such, it’s rather difficult to list all the different animals it lived alongside - it’s found in Bulgaria, China, France, Germany, Hungary, Israel, Italy, Jordan, the Netherlands, Poland, Saudi Arabia, Spain, and Switzerland. So just, assume that a marine creature from the Tethys during this time lived with Nothosaurus rather than not. 

Other: Nothosaurus has been treated as, unfortunately, a wastebasket taxon - it was discovered early enough in the history of paleontology as a science that many similar animals were just dumped into this name without any specific studies done. So, determining the factual relationships from this mess is still being worked out; in fact, it seems that this genus is paraphyletic, with many close relatives of Nothosaurus being more closely related to some species than to others. So that’s fun! 

Species Differences: The varying species of Nothosaurus tend to differ based on where and when they lived, rather than any particularly notable differences. There are some differences in size and limb proportions as well, but in general the differing species of Nothosaurus would have had very similar ecological roles. 

~ By Meig Dickson

Sources Under the Cut

Henodus isn’t what you think they are!

Looking at them, they are spectacularly turtle-like, but they’re actually a Sauropterygian! This means they’re a closer relative to Plesiosaurs than to Testudine Turtles!

For a true turtle, look for Archelon, the mega turtle of the Cretaceous!