One of the dolphin, but looks like a killer whale

One of the dolphin, but looks like a killer whale

The extermination of the bones of extinct giant dolphin (Ankylorhiza tiedemani)

Ankylorhiza tiedemani specimen

Scientists have discovered the near-complete skeleton of the first extinct large dolphin in South Carolina. This 15-foot-long dolphin (Ankylorhiza tiedemani specimen) living in the Oligocene period (about 25 million years ago), it was previously known only from a fossil of the snout.

The results were recently published in Current Biology. Ankylorhiza was the first Odontocete predator that could eat both small- and large-bodied prey and swim faster than other whales. This indicates for the first time that it was one of the few extinct cetaceans to fulfill an ecological position similar to that of killer whales.

Parallel evolution

Multiple evidence, from skull anatomy, teeth to fins, and spines suggest that the Ankylorhiza was the largest dolphin in order of odontocete. The researchers said it was the top predator in the community. They said that many of the features of the dolphin’s postcranial bones also suggest that modern minke whales must have evolved similar features independently, driven by the parallel evolution of their very similar aquatic habitats.

“We were surprised that the whales and dolphins independently achieved the same overall swimming fitness level, and that they did not evolve from the common ancestors of the two populations.” “Some features include narrowing of the tail bone, an increase in the number of tail vertebrae, and a shortening of the fin limb tibia (upper arm bone),” said Robert Boessenecker of Charleston College in South Carolina. “

“This is not obvious in different seal and sea lion pedigrees, for example, they evolved into different ways of swimming and the postcranial bones look very different.” He added,” It appears that the locking of the extra finger bones and elbows on the fins has led the two main cetaceans to a similar evolutionary path in motion. “

Picture credit: A. Gennaro

The large dolphin was first discovered from skull fragments during a 1880s phosphate excavation, but its first skeleton was discovered in the 1970s by Albert Sanders, curator of natural history at the Charleston Museum. The nearly complete bones described in the new study were discovered in the 1990s. Mark Havenstein, a commercial paleontologist, discovered it at a residential construction site in South Carolina. It was then donated to the Mays Brown Museum of Natural History for research.

Although there is much to know about this fossil specimen, the current findings suggest that Ankylorhiza is an “ecological expert.” The researchers say the species is very obvious about preying on large animals, such as killer whales.

More findings of Ankylorhiza

Another exciting aspect, according to the researchers, was that Ankylorhiza was the first whale to become a top predator by echolocation. It had giant teeth with thick roots.  They explained that when Ankylorhiza became extinct about 23 million years ago, killer sperm whales and shark-toothed whales evolved and regained the position of top predator sat in 5 million years. After the extinction of the last giant killer sperm whale about 5 million years ago, the ecological niche remained vacant until the Ice Age, when killer whales began to evolve about 1 million or 2 million years ago.

“Whales and dolphins have a complex and long evolutionary history, and at first glance you probably wouldn’t get that impression from modern species.” “The fossil record shows this long and tortuous evolutionary path, and fossils like Ankylorhiza help show how this happened,” Boessenecker said. “

Boessenecker noted that more Ankylorhiza fossils are awaiting study, including the second species and the Ankylorhiza larvae, which could help understand the growth of the dolphin. He says there’s still much to learn from the fossils of dolphins and minke whales in South Carolina.

“There are many other unique and strange early seas in the new rocks of Charleston, South Carolina. Guinea Cisse and minke whale. “Because the neophyte was the first evolution of filtering and echolocation, and because there were few marine mammals around the world during that period, the Charleston fossils provide a complete window into the early evolution of these groups, providing unparalleled evolutionary insights.”

More readings :

http://oceanfacts.net/really-fragrant-operation-sperm-whale-what-kind-of-incense-do-you-say/

http://oceanfacts.net/musician-hiding-in-the-sea-part-1/

http://oceanfacts.net/marine-elves-face-a-crisis-of-survival/

http://oceanfacts.net/major-research-shows-that-the-earths-ecology-may-collapse-one-by-one-in-the-next-10-years-the-tropical-sea-bears-the-brunt/

http://oceanfacts.net/sperm-whale-spice-maker-for-the-ocean/

Reference:

Boessenecker, R.W., Churchill, M., Buchholtz, E.A., Beatty, B.L. and Geisler, J.H., 2020. Convergent Evolution of Swimming Adaptations in Modern Whales Revealed by a Large Macrophagous Dolphin from the Oligocene of South Carolina. Current Biology.

Rajitha Dissanayake

Researcher in the field of Marine Mammals and Bio-acoustic

I'm a Master’s student in marine mammals and bio-acoustic laboratory, Institute of Deep-Sea Science and Engineering (IDSSE), Chinese Academy of Sciences (CAS) and focusing on the sustainable environmental application, conservation, and exploring all aspects of the ecology and behavior of marine mammals.

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