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Species of the infraorder Cetacea A phylogenetic tree showing the relationships among cetacean families. [1]The evolution of cetaceans is thought to have begun in the Indian subcontinent from even-toed ungulates (Artiodactyla) 50 million years ago (mya) and to have proceeded over a period of at least 15 million years. [2]
Artiocetus' name arises from a combination of cetus and artiodactyl, as this fossil was the first to show that early whales possessed artiodactyl-like ankles. Artiocetus belongs to the infraorder Cetacea, which includes whales, dolphins and porpoises. Cetus is a Latinized Greek word literally meaning "sea monster" and is used in biological ...
Comparison of even-toed ungulate and cetaceans genetic material has shown that the closest living relatives of whales and hippopotamuses is the paraphyletic group Artiodactyla. [7] [8] Dan Graur and Desmond Higgins were among the first to come to this conclusion, and included a paper published in 1994. [9]
With such parameters it surpassed in size several small theropod dinosaurs of the Early Cretaceous. [33] Gobiconodon was also a large mammal, [ 31 ] [ 32 ] it weighed 5.4 kilograms (12 lb), [ 29 ] had a skull of 10 cm (3.9 in) in length, and had 35 cm (14 in) in presacral body length.
A new study, based on fossils from 1,000 dinosaur species and paleoclimate information, found that the three main dinosaur groups adapted differently, with two of the groups evolving the ability ...
The skull shares many characteristics with other sperm whales, and is comparable in size to that of the dwarf sperm whale. Like the modern Kogia, it probably hunted squid in the twilight zone, and frequented continental slopes. The environment it inhabited was likely a calm, nearshore area with a combination sandy and hard-rock seafloor.
The order Artiodactyla consists of 349 extant species belonging to 132 genera. This does not include hybrid species or extinct prehistoric species. Modern molecular studies indicate that the 132 genera can be grouped into 23 families; these families are grouped into named suborders and many are further grouped into named clades, and some of these families are subdivided into named subfamilies.
The largest known basilosaurid, Perucetus colossus, is believed to be even bigger, with a length of about 17–20 metres (56–66 ft) and possibly comparable to, if not larger than, the modern blue whale in terms of weight, [15] though other researchers argue that it was much lighter.