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These were flightless seabirds that could dive in a fashion similar to grebes and loons (using its feet to move underwater), [12] but had beaks filled with sharp teeth. [13] Other Cretaceous seabirds included the gull-like Ichthyornithes. [14]
They were the dominant seabirds of most oceans throughout most of the Cenozoic, and modern humans apparently missed encountering them only by a tiny measure of evolutionary time: the last known pelagornithids were contemporaries of Homo habilis and the beginning of the history of technology.
The eurypterid biology is particularly suggestive of a carnivorous lifestyle. Not only were many large (in general, most predators tend to be larger than their prey), but they had stereoscopic vision (the ability to perceive depth). [37] The legs of many eurypterids were covered in thin spines, used both for locomotion and the gathering of food.
The Pacific gull is a large white-headed gull with a distinctively heavy bill.. Gulls range in size from the little gull, at 120 grams (4 + 1 ⁄ 4 ounces) and 29 centimetres (11 + 1 ⁄ 2 inches), to the great black-backed gull, at 1.75 kg (3 lb 14 oz) and 76 cm (30 in).
Fossils from North Carolina were originally thought to have been of two Fratercula species, [13] but were later reassigned to one Fratercula, the tufted puffin, and a Cerorhinca species. [14] Another extinct species, Dow's puffin (Fratercula dowi) was found on the Channel Islands of California until the Late Pleistocene or early Holocene. [11]
Many were coastal birds, strikingly resembling modern shorebirds, like Ichthyornis, or ducks, like Gansus. Some evolved as swimming hunters, like the Hesperornithiformes – a group of flightless divers resembling grebes and loons. While modern in most respects, most of these birds retained typical reptilian-like teeth and sharp claws on the manus.
The razorbill (Alca torda) is a North Atlantic colonial seabird and the only extant member of the genus Alca of the family Alcidae, the auks. It is the closest living relative of the extinct great auk (Pinguinus impennis). [4] Historically, it has also been known as "auk", [5] "razor-billed auk" [6] and "lesser auk". [7]
Some prehistoric penguin species were enormous: as tall or heavy as an adult human. [8] There was a great diversity of species in subantarctic regions, and at least one giant species in a region around 2,000 km south of the equator 35 mya , during the Late Eocene , a climate decidedly warmer than today.