ancient mammals

AMBULOCETUS


Ambulocetus quite literally means “walking whale”, and rightfully so as the ancient mammal is the suggested ancestor to the whales. Living around 50 million years ago, Ambulocetus was one of the biggest animals of its time, and one of the biggest successes. Ambulocetus had an immense advantage being able to walk on land and being an excellent swimmer.
The hunting techniques of this primitive whale were not unlike modern crocodiles, submerging itself under the water of river banks and shorelines waiting for an unsuspecting animal to approach for a drink, then pouncing with a bone crushing bite. Once prey was locked in its jaws, Ambulocetus would pull it into the water and drown it. 

Despite its appearance, Ambulocetus was already well on the way to evolving for permanent underwater living. The shape of the skull and teeth are like that of modern whales, but more intriguingly, Ambulocetus did not have ears to pick up vibrations, but instead detected them through its jaw. This form of hearing is typical of marine animals, the direction from which vibrations come from can be pinpointed with great accuracy, a quality that only adds to the success of an ocean-bound predator. 


Fossils of Ambulocetus have most commonly been found in Pakistan, it is estimated to have been able to reach up to 3 metres long. Due to Ambulocetus’s ancestry to the whales, it is described as a transitional fossil. Ambulocetus lived in a period of great significance in the whales evolutionary history, living in the middle Eocene, whale evolution accelerated and by the end of the Eocene, whales had fully immersed themselves into underwater life, they had left the land for good.
As far as evidence goes, Ambulocetus was an important but very short lived animal in life’s evolutionary history. By 49 million years ago, traces of Ambulocetus disappeared and there are few clues as to why.

like, it occurs to me now that i understand things better that monotremes actually make complete sense with our understanding of evolutionary history (since mammals came from egg-laying reptile-like ancestors) but it’s just so weird that they still exist today. these little dudes don’t care that they’re seen as a stepping stone between ancient synapsids and mammals; they want to keep doing their monotreme thing, because evolution is a tree, not a flight of stairs

Scientific Expedition to Antarctica Will Search for Dinosaurs, Ancient Mammals

Museum Curator Ross MacPhee is part of an international team of researchers traveling to Antarctica this month to search for evidence that the now-frozen continent may have been the starting point for some important species that roam the Earth today.

Millions of years ago, Antarctica was a warm, lush environment ruled by dinosaurs and inhabited by a great diversity of life. But today, the fossils that could reveal what prehistoric life was like are mostly buried under the ice of the harsh landscape, making the role Antarctica played in the evolution of vertebrates a mystery.

Aided by helicopters, scientists on this month-long expedition will conduct research in the James Ross Island group off the tip of the Antarctic Peninsula, one of the few spots on Antarctica where fossil-bearing rocks are accessible.

The team is specifically searching for fossils from the Cretaceous through Paleogene, a period about 100 million to 40 million years ago that includes the end of the Age of Dinosaurs and the beginning of the Age of Mammals. MacPhee, who has worked on the continent before, is looking to learn more about some of those early mammals during this journey.

“What I hope to achieve this time is to discover the first evidence of mammals in the Cretaceous of Antarctica, species that lived at the end of the Age of Dinosaurs,” MacPhee said. “If we can find them, they will have a lot to tell us about whether any evolutionary diversifications took place in Antarctica, and whether this was followed by species spreading from there to other portions of the ancient southern supercontinent Gondwana.”

The team is led by paleontologists from the Carnegie Museum of Natural History, The University of Texas at Austin, Ohio University, and the American Museum of Natural History and supported by the National Science Foundation as part of the Antarctic Peninsula Paleontology Project, or AP3. You can follow their exploits on Twitter at @antarcticdinos.