Caviramus schesaplanensis, a pterosaur from the Late Triassic of Switzerland (~205 mya). Known from two fossil specimens – a partial jaw and a much more complete skull and skeleton – it was about the size of a modern raven, with a length of around 60cm (2′) and a wingspan of 1.35m (4′5″).
(The more complete fossil is also sometimes considered to be a separate genus and species, Raeticodactylus filisurensis, depending on which pterosaur specialist you ask. If it was a different animal it still would have been very closely related to Caviramus, though, and the two would likely have looked very similar to each other.)
It had some odd anatomy for an early pterosaur, with proportionally long and slender limbs and a fairly heavily-built skull. There were bony crests on both its upper and lower jaws, with the upper crest probably supporting a much larger soft-tissue structure.
Powerful jaw muscles along with a combination of fang-like teeth at the front of its jaws and and serrated slicing-chewing teeth further back suggest it was specialized for eating particularly tough foods such as hard-shelled invertebrates – and it may even have been omnivorous, capable of eating plant matter as well.
Eospinus daniltshenkoi, a tetraodontiform fish from the early Eocene of Turkmenistan (~56-48 mya). Only about 5cm long (2″), it was a close relative of modern boxfish and triggerfish, as well as a completely extinct group called spinacanthids.
It was heavily armored, with large plate-like scales creating a boxfish-like carapace, but its most distinctive feature was its multiple long spines – three dorsal spines on its back, a fourth on its head resembling a “horn”, a pair of smaller spines on the sides of its body, and one on its underside formed from partially fused vestigial pelvic fins.
Boverisuchus magnifrons*, a crocodilian from the early Eocene of Germany (~50-40 mya). Reaching about 3m long (9′10″) it was much more heavily armored than its modern cousins, with an interlocking “exoskeleton” of bony osteoderms covering its body and limbs – leading to it being given the nickname “panzer croc”.
It was adapted for walking and running on land, with relatively long legs and surprisingly hoof-like claws. It may even have carried its weight directly on these hooves similar to mammalian ungulates.
And if that’s not unusual enough, its hind leg musculature suggests it also might have been capable of short bursts of bipedal sprinting.
[ * Originally known as Pristichampsus rollinatii before being reassigned in 2013.]
Phenacodus primaevus, a mammal from the Late Paleocene to Middle Eocene of North America and Europe (~60-48 mya). About 1.5m long (5′), it’s thought to have been one of the earliest known odd-toed ungulates, walking on its middle three hoofed toes.
Its teeth were adapted for a diet of mostly plant matter, although it may also have been opportunistically omnivorous.
Another species in the same genus, Phenacodus intermedius, had a skull structure that suggests it might have had a muscular prehensile upper lip – or perhaps even a short tapir-like proboscis.