u/DifficultDiet4900

Mastodonsaurus was a genus of giant capitosaur temnospondyl amphibian from the mid Triassic of Europe. At 5 meters long, it was the largest known amphibian with a skull length of over a meter. Mastodonsaurus lived in a variety of habitats, ranging from rivers, lakes, and even marine lagoons. Most of the largest individuals have been found in deep, well-aerated lakes with depths less than 10 meters. The skull was flat and broad with narrow grooves along the surface of the bone called sulci. These grooves show it had sensory organs that could detect vibrations and pressure under water. Its not unlike that of the lateral lines on fish and macroreceptory systems seen in reptiles, allowing Mastodonsaurus to sense prey in low light conditions. A pair of

massive tusks grew from the tip of the lower jaw. When the mouth is closed, these tusks pass through special openings called palatal fenestrae in the upper jaw, poking straight out through the top of its snout. These tusks were for peircing prey and preventing them from escaping. Mastodonsaurus was a bottom dwelling ambush predator, waiting for prey to come near enough for a fast strike. It was the apex predator of Triassic waterways in Europe, feeding on large amphibians like Plagiosuchus and fish, but could possibly have also hunted terrestrial vertebrates as well. The limbs of Mastodonsaurus were greatly reduced and had weakly developed joints, indicating it was poorly equipped for walking on land. Mastodonsaurus likely died en masse during droughts when the water levels were too low for them to move. Juveniles likely didn't have this restriction, however.

​

https://www.researchgate.net/publication/408252266\_Redescription\_of\_the\_holotypes\_of\_Tylosaurus\_proriger\_and\_Tylosaurus\_nepaeolicus\_Squamata\_Mosasauridae

https://palaeo-electronica.org/content/2026/5872-otodus-megalodon-vertebrae-from-denmark

A large giganotosaurine carcharodontosaurid from the early Cretaceous Cerro Barcino formation in Argentina. Tyrannotitan is the earliest member of the gigianotosaurines and lacks some of the features of derived taxa such as the long sickle-like pedal ungual. It had an unusually robust build and reduced forelimbs, somewhat similar to a tyrannosaurid. Tyrannotitan has a preserved tall anterior caudal neutral spine. It probably had a hump-like structure on its tail similar to Concavenator. At nearly 12 meters long and weighing 7 tonnes, Tyrannotitan is deserving of its name.

https://sciencepress.mnhn.fr/en/periodiques/geodiversitas/48/12

Deinosuchus riograndensis was a species of giant estuarine alligatoroid from the Campanian of North America. It might be the largest crocodylian in the mesozoic, with the largest reliable specimens reaching sizes over 9 meters and the weight of an Asian elephant. The head of Deinosuchus was disproportionately large compared to its body. The skull was broad and wide, with a full length less than 150 cm. There is notably an inflated bulb of bone on the tip of the snout. While its exact function remains debated, it could have probably helped stabilize the jaw when biting and resist stress when grabbing large prey and/or as a display structure. Its bite force was estimated to be 18,000 N to 102,803 N, a very wide range based on modern alligators. Such powerful jaws and the ability of "death rolling" would have allowed Deinosuchus to hunt larger animals than its contemporaries. Deinosuchus is often considered a dinosaur hunter based on feeding traces on dinosaur bones attributed to it. The most noteworthy example is NJSM 13096, a tyrannosauroid leg bone (likely a tibia or metatarsal) from the Ellisdale Fossil Site in New Jersey that had bite marks on it. However, it remains controversial as to whether these dinosaurs were killed by Deinosuchus or merely scavenged, but in the case of the tyrannosauroid, the former is more likely. While it is famous for occasionally eating large dinosaurs, they likely weren't its primary source of prey. Several large fossilized coprolites referred to Deinosuchus contain numerous fragments of turtle shells. In fact, more than a dozen sea turtle shells from the Campanian have been found with massive bite marks made by the giant crocodylian. Some of these shells even show signs of healing, indicating they were attacked and managed to escape. The coastal and estuarine environments Deinosuchus was often found in were abundant with marine and brackish turtle species. The design of its thick and blunted teeth was perfectly adapted for bone-crushing and shattering these shells. This is even further supported by the often catastrophic damage on their teeth. The dorsum of Deinosuchus would have looked more like a bony Dalek chassis. Now, of course, Deinosuchus was still a generalist that could feed on a variety of large prey items. Based on its thick, deeply pitted osteoderms, it seems to suggest strong muscle anchors that would have allowed Deinosuchus to haul its immense weight out of the water. However, given the large head and gracile limbs, Deinosuchus was unable to walk on land. Instead, it would have dragged itself on the ground using a slow, sprawling, belly-crawling gait similar to the modern indian gharial. It isn't known why Deinosuchus went extinct, but a cooling climate and lowering of sea levels are the leading theories.

(Manga is Dandadan)

https://onlinelibrary.wiley.com/doi/10.1111/pala.70064

​

A possible colossal titanosaur from the Maastrichtian Kallamedu formation in India. It was initially misidentified as a large theropod but was later determined to be from a titanosaurian sauropod of massive size. Some estimates claim it was even larger than Argentinosaurus at over 40 meters long and 110+ tonnes. However, with the material now mostly lost, its immense size isn't very sound. Some have argued that Bruhathkayosaurus shouldn't be valid and instead rendered a nomen dubium, as the ICZN status of Bruhathkayosaurus remains debated. The original paper was horrible, and a proper holotype was never established. I will continue to call it Bruhathkayosaurus for now until further notice, but keep in mind this name is on shaky ground at best.

There are several isolated elements of giant azhdarchid pterosaurs from Maastrichtian Haţeg islands in Romania. With wingspans ranging from 6 meters (FGGUB R1625) to possibly 12 meters ("Dracula"), they're among the largest pterosaurs known. Unfortunately, almost none of them overlap, and from slightly different localities.

​

https://www.science.org/content/article/some-spinosaurs-cried-salty-tears-thrive-brackish-waters?fbclid=Iwb21leASFI4FjbGNrBIUjfWV4dG4DYWVtAjExAHNydGMGYXBwX2lkDDM1MDY4NTUzMTcyOAABHkeJI1V6Lmr50RTKISLWE7rAmEj2-3TP\_iwmp7FNazK7mbAjEKngg7pgeaZ5\_aem\_FZD\_YLnCJyLJWEesCFfZ9Q

Rexarthuria cliftii, comb. nov. represents the oldest azhdarchoid material presently known from Europe.

https://www.tandfonline.com/doi/full/10.1080/02724634.2026.2664783