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Artiodactyls live on every major landmass and throughout the oceans and in a variety of habitats, including forests, grasslands, and deserts. They come in a wide array of body plans in contrasting shapes and sizes, ranging from the 38 cm (15 in) long and 2.5 kg (5.5 lb) royal antelope to the 27 m (89 ft) long and 120 ton blue whale.
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. Cetaceans are fully aquatic mammals belonging to the order Artiodactyla and branched off from other artiodactyls around 50 mya.
Molecular findings and morphological indications suggest that artiodactyls, as traditionally defined, are paraphyletic with respect to cetaceans. Cetaceans are deeply nested within the former; the two groups together form a monophyletic taxon, for which the name Cetartiodactyla is sometimes used.
Cetaceans are deeply nested within the artiodactyls; the two groups together form a clade, a natural group with a common ancestor, for which the name Cetartiodactyla is sometimes used. Modern nomenclature divides Artiodactyla (or Cetartiodactyla) into four subordinate taxa: camelids (Tylopoda), pigs and peccaries (Suina), ruminants (Ruminantia ...
The family Balaenidae, the right whales, contains two genera and four species. All right whales have no ventral grooves; a distinctive head shape with a strongly arched, narrow rostrum, bowed lower jaw; lower lips that enfold the sides and front of the rostrum; and long, narrow, elastic baleen plates (up to nine times longer than wide) with fine baleen fringes.
Adult female and fetal (in blue) Maiacetus Life restoration. The genus contains a single species, Maiacetus inuus, first described in 2009 on the basis of two specimens, including a specimen which has been interpreted as a pregnant female and her fetus. [1] This represents the first description of a fetal skeleton of an archaeocete.
The body mass formula based on astragali was previously established by Jean-Noël Martinez and Sudre in 1995 for Palaeogene artiodactyls, although Mixtotherium was not included in the initial study. [ 34 ] [ 35 ] The body mass of two mixtotheriid species have been estimated by Orliac et al. in 2021 based on a formula using dental measurements.
Ichthyolestes is the smallest pakicetid, approximately 29% smaller than Pakicetus, and has been considered “fox-sized.” [9] They retain many features typical of terrestrial Eocene artiodactyls, including long and gracile limb bones, a fused sacrum, small mandibular foramen, and no cranial telescoping.