The Evolution of Seals

in the northern reaches of Canada North American river otters withstand the cold and snow in order to take advantage of the good fishing spots found here 23 million years ago another small aquatic mammalian Carnival was living the same lifestyle of fishing in the chilling Canadian rivers and walking across the frozen ground to get to other waterways however although this creature looked and lived just like an otter its skull was a different shape and they had foreign sizes instead of the Otters sex these features among others out at it's true grouping it was called pure yellow Darwin eye and is the oldest known seal seals scientifically known as pinnipeds Arcana forms which are mammalian carnivores that are more closely related to dogs than the Artic at their closest relatives in this group are actually not otters otters are just another separate lineage of aquatic mammal than a more closely related to badges and weasels the closest relative of seals are actually bears and they probably diverged from each other over 40 million years ago in the Eocene period that Darwin I is the oldest known pinniped who was actually probably more developed to an aquatic life style than otters are and most likely swam in a different way they had very large hands and long fingers for their body size meaning it is highly likely that they were webbed however their tails don't seem to have made any specializations for swimming this means they probably propelled themselves through the water using their limbs or as otters use their flat tails this makes sense seeing as modern species of seal use their fins to swim rather than their tail like otters and whales do this is a method of propulsion that seems to be rarer in terrestrial animals that have evolved to live in the water and seals share this trait with plesiosaur marine reptiles there was another freshwater otter like seal called protein aetherium meaning riverbeast that is known from France and Germany showing that these freshwater legs seals were successful spreading throughout the northern hemisphere the first ocean-going seal that resembled how they look today appeared about 23 million years ago in the early Maya scene but the freshwater river beasts lived on until about ten million years ago the existence of the otter like seals and the sea or lake seals overlapped for a very long time and the river beasts were their own distinct stem group of animals living their own lives it's just the ocean-going seals are the only ones that survived into the present the first seal that took to the ocean was called NLE Octus that would have swum on the west coast of america it had a short tail and short legs that could probably be referred to as fins meaning that this was the first seal that started to really look like seals as we know them today but his femur was still almost twice as long as living seals meaning its hind legs would still be noticeable and their femur would eventually shrink down to the point where it was almost like a joint bone Annalee arctos used its hind and front limb to propel itself in the water which has actually resolved a dispute between scientists about the living seal families the three living seal families are known as fossa day which contains the most arrived seals and have no ears as well as most Antarctic seals like leopard seals or elephant seals Otara day which contains seals like sea lions and oda been a day which has only one living member the walrus and all of these animals use different methods of propulsion in the water making many scientists conclude that seals descended from to terrestrial lineages no Terra dare use their four limbs to move in the water whereas folks today used their hind limbs and Waris used both if NLE arctos was the common ancestor of all the modern seal groups then it would just be the case that our Terra de stopped using their hind limbs in movement and folks today stopped using their forelimbs and waris's may have separated from these two groups early on and just retained using all their fins to swim solving the mystery despite the fact that an early arctas had many specializations making it more adapted for swimming it probably would have been more tied to the shore with in current day seals this is because their teeth were more similar to terrestrial carnivores like bears and were more adapted for slicing than piercing this would mean that they would need to return to the shore with their prey before cutting it up and digesting it a seal called IO Tarija krypter that lived about 16 million years ago possessed the beginnings of what was the modern seal jaw and shows a transition between the bear like teeth and the modern seal teeth freeing them up from the coast and allowing them to swim for longer periods of time in the late oolagah scene and Maya seen the oceans ecosystems were changing and beginning the process where they would take on their current forms there was a drastic increase in the amount of baleen whale species penguins had spread throughout the southern hemisphere echolocating dolphins first appeared and now seals had entered the seas as well the first dolphins like Kent Rhea Don may have presented fishing competition with seals and there is reason to believe that they could have been better predators as they had echolocation and dolphins are nearly always faster than seals however seals have very bendy spines and although slower are often more agile and so may have been better adapted at eating slower and more maneuverable fish and this bendy spine is seen in seals as early as an early arctos another benefit that seal have not shared by toothed whales is that they can go onto land this is useful for escaping predators but also can be used to catch prey leopard seals are one of the only seals that has adapted to eating larger animals and fish and unlike orcas is able to hunt penguins in the water but also on land seals and these other new ocean-going animals that appeared in the Maya scene would have offered new feeding opportunities for larger predators as well most notably a new group of large predatory whales known as the raptorial sperm whales so they were relatives of modern sperm whales who were not specialized squid eaters and instead would have eaten vertebrate prey like seals sperm whales have a feeding mechanism that is largely dominated by them sucking in their prey that will be crushed once the whale has swallowed them and their teeth are only on the bottom jaw and are only really used to grapple onto the animal to help with this process the macro raptorial sperm whales on the other hand have very clear evidence showing that they did not feed in this way they had strong and larger muscles in their jaws and had much larger teeth that were on their bottom and top jaw there were far too sharp and specialised for grappling they would have used these to cut and tear animals and we could have easily crushed through a seal it is traditionally thought the macro raptorial sperm whales adapted in response to the dramatic increase in baleen whale diversity that occurred in the Maya scene and although this is almost certainly true it is likely that the appearance of seals played a big part in this as well whereas large sperm whales were probably specialized whale hunters small wrapped orioles like a crow fighter were only about four meters long and so were probably too small to hunt whales however still possess the sharp teeth of other wraps for eels so could have been big seal hunters as recently as four million years ago baleen whales started approaching their gargantuan sizes that they are today and decreased in diversity which was probably a big factor in the extinction of Megalodon and the large raptorial sperm whales with the era of super predators over the newer smaller apex predators of the ocean killer whales and great whites change their attention to seals becoming seal eating specialists so seals may have created selective pressures that change the oceans apex predators so seals don't just represent another amazing transformation from a terrestrial animal to an aquatic one for a drove the evolution of other creatures and were adamant in oceanic ecosystems taking on their current forms thank you for watching if you would like to be notified of future content then consider subscribing a massive thanks to my patrons for supporting me especially green fools and a fossil worth if you would like to support me as well then you can go to patreon and make a pledge you

Channel: Moth Light Media

Views: 177,426

Rating: 4.9595118 out of 5

Keywords: Seal, Evolution of Seals, Puijila, Potamotherium, Eneliarctos, Walrus, Seal Evolution, evolution, aquatic mammal, sea mammal, river seals, otter, evolution of otters, moth light media, paleontology, biology

Id: aAOsf004FqQ

Length: 8min 2sec (482 seconds)

Published: Thu Dec 19 2019

Reddit Comments

[u/satsumapen619]

I love this kind of stuff. So amazing to see how things evolve and change.