Search results
Case Studies in Ecology and Evolution DRAFT D. Stratton 2011 1 1 Phylogenetic History: The Evolution of Marine Mammals Think for a moment about marine mammals: seals, walruses, dugongs and whales. Seals and walruses are primarily cold-water species that eat mostly fish and can spend part of their time on land (or ice).
Jan 17, 2018 · The pinnipeds are the youngest group of marine mammals, originating about 25 million years ago during the late Oligocene period. They are arctoid carnivores within the order Carnivora, and appear to have evolved from primitive bears. They are therefore closely related to modern bears, as well as the mustelids (weasels, skunks, otters and kin).
Sep 24, 2014 · Although land-based mammals were increasing in diversity, few or none were present in the oceans. The basic hypothesis is that the early whale-like artiodactyls, like Indohyus and Pakicetus were land-based (terrestrial) mammals that spent most of their time near the water's edge. Over time, they adapted to the niches in the ocean.
Oct 16, 2021 · In fact, the first mammals evolved from a population of vertebrates called therapsids (mammal-like reptiles) at the end of the Triassic period and coexisted with dinosaurs throughout the Mesozoic Era. But part of this folktale has a grain of truth. It was only after the dinosaurs went kaput that mammals were able to evolve beyond their tiny ...
Oct 23, 2019 · The oldest known haramiyids are from 208 million years ago in the Triassic. If they are true mammals, then mammal origins date back at least that far — if not, then the oldest known mammal is ...
Nov 15, 2019 · 2.1.1 Archaeoceti. The story of Cetacea began with the evolutionary radiation of placental mammals after the extinction of the dinosaurs and most large marine reptiles at the end of the Cretaceous about 66 million years ago (hereafter written Mya) (Fig. 2.1).
Hippos likely evolved from a group of anthracotheres about 15 million years ago, the first whales evolved over 50 million years ago, and the ancestors of both these groups were terrestrial. These first whales, such as Pakicetus, were typical land animals. They had long skulls and large teeth that could be used for eating meat.
