A study reports that crocodile ancestry adapted to life in the ocean and developed inner ear modifications also present in whales – only at an earlier time.
According to Reuters, the study that was published on Monday reveals that some 170 million years ago, some land crocodiles faced an unusual change in their habitat, forcing them to move to ocean environments.
The study shed light on marine crocodiles called ‘thalattosuchians,’ which appeared in the Early Jurrasic Period and went extinct during the Early Cretaceous Period. They belonged to the Neosuchian Clade, contrary to today’s crocodiles, which belong to Clade Eusuchia.
I am very happy to announce that my first PhD paper just got published in PNAS!!!????????
Check it out if you want to know how the #innerear changed as ancient crocodile relatives called #thalattosuchia became fully aquatic.@LeverhulmeTrust @GeosciencesEd https://t.co/ApVnvqU2XO pic.twitter.com/zzjonAOnId
— Julia Schwab (@Julia__Schwab) April 20, 2020
Survival of the fittest
Based on the study, these ancestors of today’s crocodiles could reach up to about 33 feet long and have split to different classes as not all of them were able to adapt to life in the open ocean.
Some of the thalattosuchians like the Teleosaurus and Machimosaurus remained semi-aquatic, only looking to prey on fish and smaller ocean creatures, while other members of the ancestry were able to completely adapt to the conditions of the open ocean and preyed on bigger fishes and other marine forms.
The aquatic ability of the thalattosuchians was seen through the physical changes that occurred in both of its semi-aquatic and fully-aquatic counterparts.
How the inner ear changed with respect to the marine beast’s environments
Julia Schwab, lead author of the published study, and other paleontologists from the University of Edinburgh studied the thalattosuchians’ skulls and found that it has adapted its inner ear parts as it shifted from its original habitat to the oceans.
Computerized axial tomography (CAT) scans showed changes in the inner ear’s vestibular system. It is found that the changes were more noticeable amongst fully-aquatic thalattosuchians. Similar to whales, their ear canals became fatter and smaller as it transitioned from its semi-aquatic to the fully-aquatic phase.
Reportedly, this narrowing of the ear canal made the thalattosuchian’s sensory system more suited to life in the oceans. This also enabled them to obtain the needed buoyancy, which kept them afloat during their time in the oceans.
The study concluded that both crocodiles and whales manifested similar changes despite living independently of each other at different eras.
The study marks a milestone in the study of evolution
Scientists lauded the group of researchers after having read their paper in the journal Proceedings of the National Academy of Sciences and cites that such discovery is of great importance and that knowledge on ancient animals’ sensory organs are “key” to understand how they lived. They add that this, together with other discoveries on other key areas such as astronomy and biology, will contribute to man’s holistic understanding of how things came to be – in Earth, and beyond.
— Mostly Mammoths (@MostlyMammoths) May 9, 2018
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