40 kya. Penghu Islands, to the west of Taiwan.

A Ursus arctos penghuensis wanders out of a basaltic cave, stepping into the temperate grassland along with her cubs. At 450 kilograms, she's an absolute unit among female brown bears. Still, she cannot afford to tread carelessly, for the males of her kind can reach twice her weight and are cannibalistic towards cubs.

U. arctos penghuensis might be the largest subspecies of brown bear ever discovered; workers found out that the only known specimen (a robust lower jawbone to be exact, NMNS006391-F051712) is 27% bigger than the steppe brown bear (U. arctos “priscus”), which is widely thought to be the biggest known extant and extinct brown bear variants.

It's not possible for brown bears with such enormous dimensions to sustain on carcasses or plants alone. Thanks to the abundance of contemporary large game animals and possibly insular gigantism, U. arctos penghuensis was the undisputed king of the Late Pleistocene islands of Penghu.

Stegos were once thought to be extremely slow ornistischians because of their hip height being disproportional and short legs, however that was in the past with a different setting and array of its skeleton. They once estimated them to be able to run only 7 km/h or 5mph, which we now know it's false, considering articles by Ruben Molina-Perez, Asier Larramendi, David B. Weishampel and David E. Fastovsky, which upscaled his speed to up to 12 miles per hour or 18 km/h.

This doesn't seems much, until you remember that's more than the average human sprint speed and its probably more than many other ornistischians, even ceratopsians (yes, Stego was faster than Triceratops) and hadrosaurids running on their four limbs. Just imagine a freight train of spikes running at you. No wonder why Allos tried hunting those things once in a lifetime lol.

And to add: Stego tail and thagomizers could be swung at speeds of over 90mph and create a pressure in the order of the Mariana Trench Challenger Deep and puncture things with a thousand times the pressure of atmosphere.

https://www.deviantart.com/aesirr/art/Hell-Creek-Formation-Fauna-1165120310

The only group of animals to ever dominate the ecosystem with dinosaurs they ruled the land on triassic and they were reletives of crocodiles yet get very little media focus

https://youtu.be/3_fSL1ZDYSE?si=H5DjjkNKpok_2GEs

Nature's Compendemium

Size and Discovery

The Hector's Ichthyosaur is a giant specimen of Ichthyosaurid on New Zeland, that measured 37 to 40 metres long and weighed 170 to 290 tons (251-280 long tons). The know material is a fragmentary's Vertebraes; The specimen know is the KZND 465-1/28, he is compared on Blue Whale, Shastasaurus, Ichthyotitan and Shonisaurus popularis.

The Hector's Ichthyosaur was discovery in New Zeland from James Hector in 1873, the fossil inclueding a fragmentary vertebraes, ribs, humerus and a possible tooth and a note was publiced, but the fossils was lost. Today, Hector's Ichthyosaurus is considered a dubious or invalid animal, causing it to no longer be recognized as commonly in paleontology and scientific culture.

Diet

The diet of Hector's Ichthyosaur is not know, but a study of 2000s considered a note of the skeleton reconstruction of "Ichthyosaurus" hectori (or Hector's Ichthyosaur), he came to the conclusion that the animal probably fed on large fish, molluscs, shells and extinct natilus species.

Today, the validity of the "Hector's Ichthyosaur" is disputed and is not more considered a valid species second a paper of 2022. Some paleontologists suggest that Hector's Ichthyosaur is actually a junior synonym of Shastasaurus, but there are paleontologists who suggest that they are separate species.

References:

C. A. Fleming, D. R. Gregg & S. P. Welles (1971). New Zealand Ichthyosaurs—a summary, including new records from the Cretaceous. Taylor & Francis 14:4, 734-741

J. D. Campbell (1965). New Zealand triassic saurians. Taylor & Francis 8:3, 505-509

Giant marine reptiles of North Canterbury. www.yotube.com