The earliest known ancestor of arctic whales is Denebola brachycephala from the late Miocene around 9–10 million years ago. [55] A single fossil from Baja California indicates the family once inhabited warmer waters.

Our findings suggest that some genes lost in ancestral cetaceans were likely involved in adapting to a fully aquatic lifestyle. The ancestors of modern cetaceans (whales, dolphins, and porpoises) transitioned from a terrestrial to a fully aquatic lifestyle during the …

2018年1月1日 · Cetaceans show major evolutionary patterns linked to oceanic change, supporting the idea that food resources have helped to drive cetacean history. The exact roles of physical versus biological effects, viz., bottom-up or top …

2017年6月5日 · Crown cetaceans: A clade defined by the most recent common ancestor between all living baleen and toothed whales, and all of their descendants, extinct or extant. Some authors have also called this clade Neoceti [31]. The oldest crown cetacean is the stem mysticete Mystacodon selenensis, whose estimated age is about 36.4 Ma [33].

A phylogeny showing the relationships among cetacean families. [1] The Cetaceans (whales, dolphins and porpoises) are mammalian marine descendants of land mammals. Their terrestrial origins are indicated by: Their need to breathe air from the surface; The bones of their fins, which resemble the limbs of land mammals

2021年11月2日 · Cetacean evolution is among the best-characterized morphological and ecological transitions from a terrestrial to an aquatic existence. Cetaceans likely originated ∼ 52.5 million years ago

The terrestrial precursor of the cetacean is the same ancestor of artiodactyls (eg. cows, deer and sheep). This common ancestor was a wolf-like creature called Mesonychid condylarth. Mesonychids were completely terrestrial and their eating habits ranged from carnivorous, herbaceous and omnivorous.

Even though all modern cetaceans are obligate aquatic mammals, early cetaceans were amphibious, and their ancestors were terrestrial artiodactyls, similar to small deer. The transition from land to water is documented by a series of intermediate fossils, many of which are known from India and Pakistan.

2016年4月1日 · The origin of cetaceans was originally thought to be defined by their adoption of an aquatic lifestyle, and the morphological and physiological changes that such a step necessitates. This chapter provides an overview of the changes that affected the major sense organs during the terrestrial-aquatic transition of cetaceans.

2009年1月1日 · Fossils show that cetaceans arose from terrestrial ancestors more than 50 million years ago. They have evolved to become the dominant group of marine mammals in terms of taxonomic and ecological diversity and geographic range. Structural, genetical, and ecological patterns in living species are used widely to infer cetacean evolution.