Friday, 5 April 2019

Another 'Non-Existent' Transitional Fossil

Peregocetus pacificus
© A. Gennari
Ancient four-legged whale with webbed feet and hooves uncovered in Peru | Natural History Museum

Another discovery this week of one of those 'non-existent' intermediate fossils is causing creationists to think of inventive ways to explain it away and so maintain the myth that these things just aren't really there.

This time it closes another gap in the story of the evolution of whales - or as creationists will probably claim, it opens up two gaps now where there was previously only one.

Creationism's detachment from reality is possibly best seen in their constant claim that there are no transitional or intermediate fossils, despite the abundance of such fossils. In one sense of course all fossils are intermediate in that they come between their parents and their descendants and represent a snapshot of that evolutionary branch at that place and point in time. But what creationists are probably thinking of is species showing clear characteristics intermediate between an ancestor and a different living species altogether.

Of course, there is an abundance of fossils that are very clearly intermediate between ancestral and modern species, and of extinct stem species which lie at the root of related taxons near to or at the point of divergence. This is how we can tell how different taxons are related.

This is the first indisputable record of a quadrupedal whale skeleton for the whole Pacific Ocean, probably the oldest for the Americas and the most complete outside India and Pakistan.

Dr Olivier Lambert, Co-author,
Royal Belgian Institute of Natural Sciences,
Quoted in Natural History Museum News.
This particular examples was found in the Peruvian coastal desert in an area rich in marine fossils, including filter-feeding whales from about 36.4 million years ago. This specimen however comes from some 10.2 million years earlier, as shown by index micro-fossils of known age.

Because the earliest whale fossils are found in India and Pakistan, whales are believed to have evolved in south Asia about 50 million years ago. What remains uncertain is the route these whale ancestors took as the spread around the globe.

The evolution of whales is perhaps the best-documented example of macroevolution that we have, with the group going from small, dog-sized, hoofed mammals to the giants of the ocean we know and love today. However, despite having a good fossil record of the different stages involved, there are still questions remaining as to the routes that early whales took when they first spread around the world.

Travis Park
Post-doctoral Fellow, Natural History MUseum, London
Quoted in Natural History Museum News.
It was unearthed by a team led by Oliver Lambert of Royal Belbian Insitute of Natural Science. Their results were published in Current Biology yesterday.

This new specimen has a combination of features adapted for terrestrial and aquatic living. It had four limbs with each toe ending in a small hoof. The legs would have been capable of supporting the bodyweight and walking on land. However the toes show signs that they were probably webbed, rather like an otter's. The vertebrae of the tail are similar to those seen in otters and beavers, suggesting that it was used for swimming with an undulating movement, probably giving it a powerful swimming ability as a predator on fish.

Because this species was probably still tied to the land, spread from south Asia to South America would have been via a coastal route to southern Africa then across the South Atlantic at a time when the distance between Africa and South America was half what it is today. This means that within about 10 million years of the earliest whales evolving, they had dispersed all around the world into available niches in Earth's oceans.

Once more we see creationism, and the claims on which it's based, refuted by the simple device of discovering the facts.


Reference:
Olivier Lambert,Giovanni Bianucci,Rodolfo Salas-Gismondi,Claudio Di Celma,Etienne Steurbaut,Mario Urbina,Christian de Muizon
An Amphibious Whale from the Middle Eocene of Peru Reveals Early South Pacific Dispersal of Quadrupedal Cetaceans
Current Biology
(2019) doi: 10.1016/j.cub.2019.02.050







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