What are dolphins descended from?

Dolphins are descendants of land-dwelling mammals of the artiodactyl order (even-toed ungulates). They are related to the Indohyus, an extinct chevrotain-like ungulate, from which they split approximately 48 million years ago.

What type of marine mammal is a dolphin?

Cetaceans
Types of marine mammals Cetaceans (whales, porpoises, and dolphins) are categorized into two main groups: baleen whales (mysticetes) and toothed whales (odontocetes). They spend their lives in water, and have many adaptations to their entirely aquatic lifestyle. ​There are over 70 different species of cetacean.

What is the shared ancestor of whales and dolphins thought to be?

All Whales and Dolphins are a member of the Even-toed Ungulates or Artiodactyla. The groups closest living relatives are Hippos, sharing an ancestor approximately 47 million years ago. Once upon time, it was thought that Whales and Dolphins were closely related to extinct land-dwelling carnivores.

Do all marine mammals have a common ancestor?

Although all marine mammals evolved from land mammals, it may surprise some that each group of marine mammals has its own unique ancestry. Through convergent evolution, each of these groups separately evolved similar body structures as they adapted to a life in the marine environment.

What marine reptile looks most similar to a dolphin?

ichthyosaurs
Despite their distance from the oceanic mammals in both time and evolutionary history, though, ichthyosaurs look enough like dolphins for the two to be practically inseparable in textbooks.

What was the first marine mammal?

Basilosauridae: the First Fully Aquatic Cetaceans. In the late middle Eocene, around 41 million years ago, a new kind of cetacean emerged, the first one that resembles modern cetaceans: Basilosauridae (Uhen 1998).

How can we solidify the dolphin family tree?

Until now, solidifying the dolphin family tree has been a logistical headache. Classic studies of body shape and features have outlined the general branches, but DNA analysis is required to confirm the placement of species on those branches. Modern genomic techniques

What does the dolphin family tree tell us about whales?

The dolphin family tree may even shed light on long-standing questions about the evolution of whales from terrestrial ancestors. As they evolved from hooved land animals, dolphin bodies transformed dramatically—flippers developed, nostrils repositioned, and underwater hearing came about.

What are the three orders of marine mammals?

Extant marine mammals include more than 120 species belonging to three distinct mammalian orders: Carnivora (walruses, sea lions and other pinnipeds), Cetacea (whales, dolphins and porpoises) and Sirenia (manatees and dugongs).

What does a phylogenetic tree say about a species?

What the tree does say is that species A shares a common ancestor with the other species. Finally, when considering phylogenetic trees we will often be interested in the monophyletic groups. A monophyletic group, or clade, is defined as the allof the descendants of a single common ancestor.