Prehistoric whales advanced massive brains sooner than as soon as thought whereas retaining sense of scent

Friday, July 25, 2025

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In the desert simply west of Faiyum, Egypt, is the world’s largest focus of
prehistoric whale fossils, a UNESCO World Heritage web site referred to as Wadi Al-Hitan — Whale
Valley.

Abdullah Gohar, a Ph.D. pupil in anatomy and vertebrate paleontology at OSU Center for Health Sciences, grew up in Faiyum and now research how whales advanced from prehistoric land mammals
to dwelling totally in water. 

“It has hundreds of complete whale skeletons all over the place,” Gohar mentioned. “The
earliest whale fossils got here from the Eocene epoch, which is principally from round
55 million years in the past till 33 million years in the past. This is the golden age of whales
as a result of they began there and proceed immediately.”

At OSU-CHS, Gohar research beneath paleontologist Holly Woodward Ballard, PhD., a professor
of anatomy specializing in paleohistology.

He can also be certainly one of a number of co-authors from universities in Germany, Italy, Egypt and
Oklahoma whose analysis into the evolution of whale brains was recently published in the scientific journal Evolution.

The researchers studied high-resolution CT scans of the cranium fossils of two early
whales: Protocetus, which lived about 43 million years in the past, and Aegyptocetus, which
lived about 41 million years in the past. 

Both had been semi-aquatic whales, that means they frolicked on land in addition to in water,
primarily based on the olfactory bulbs and canals and different components of their anatomy and morphology.

Gohar mentioned they’d a fancy ethmoid bone, which separates the nasal cavity from
the mind. 

“If you will have well-developed ethmoid bones, this implies you will have a fancy sense of
scent,” he mentioned. “The dwelling whales immediately have both a very lowered sense of scent,
like in baleen whales or a totally absent sense of scent, like in dolphins or toothed
whales. But terrestrial mammals, as a result of they want this on land, they’ve a well-developed
sense of scent.”

This additional helps the proof that Aegyptocetus and Protocetus had been midpoint
species within the evolution of whales from terrestrial to totally aquatic mammals, Gohar
mentioned. 

Using the CT scans of the inside of the cranium fossils, the workforce was additionally capable of
examine the mind circumstances to find out the mind measurement relative to the general measurement of
each animals.

“Cetaceans immediately — whales, dolphins, porpoises — have one of many largest brains relative
to their physique measurement. I believe they arrive second after primates. Scientists all the time believed
that this occurred after they grew to become totally aquatic. The adaptation to be totally aquatic
triggered them to have a really massive mind measurement relative to their physique measurement,” he mentioned.

But finding out the mind circumstances of Protocetus and Aegyptocetus, Gohar mentioned the analysis
workforce discovered that wasn’t the case with these semi-aquatic whales, which had been roughly
10 to 13 toes lengthy.

“They usually are not totally aquatic but, however they nonetheless have this massive mind measurement relative
to their physique measurement,” he mentioned. “This implies that Protocetus not solely has a giant mind
measurement relative to its physique measurement but additionally has a well-developed sense of scent. This
sense of scent isn’t necessary when they’re diving underwater, nevertheless it’s really
essential on land.” 

Gohar mentioned early whales remained on this semi-aquatic state for a very long time, about
seven to 10 million years, earlier than turning into totally aquatic.

“It was actually necessary for them to chill down as a result of the Eocene epoch, the time
of the origin of whales, it was a very, actually sizzling time. They skilled vital
international warming at the moment,” he mentioned. “This is among the hypotheses of why they
went into the water within the first place, to chill down and seek for meals, as a result of
there weren’t quite a lot of animals dwelling on land at the moment due to the new climate.”

Woodward Ballard mentioned that figuring out that these semi-aquatic whales had massive mind
sizes and a well-developed sense of scent concurrently hundreds of thousands of years in the past can
assist us perceive animals immediately.

“The paper’s authors present that mind enlargement started whereas whales nonetheless relied on
terrestrial environments, suggesting it was a pre-adaptive trait that supported their
shift to a completely aquatic ecology,” she mentioned. “Understanding this sequence of trait
acquisitions additionally helps predict how trendy amphibious mammals like seals and otters
may evolve.”

Gohar can also be a part of a analysis workforce led by Egyptian paleontologist Hesham Sallam,
a professor on the American University in Cairo and founding father of the Mansoura University
Vertebrate Paleontology Center in Mansoura, Egypt.

Sallam, who can also be a co-author on the examine, mentioned it’s an thrilling time to be a paleontologist
finding out these fossils present in Egypt.

“Egyptian fossils stay a goldmine for understanding main evolutionary transitions,
such because the evolution of whales. Studying the mind anatomy of those historical whales
presents us a novel window into the second when whales started to cognitively diverge
from life on land whereas nonetheless retaining their ancestral sensory ties to it,” he mentioned.

Gohar mentioned he’ll proceed to review the evolution of whales earlier than he graduates from
OSU-CHS in a number of years. Then, he plans to return to Egypt to proceed his analysis
and move on what he has discovered to others.

“The very first thing I wish to do is switch the data. The Ph.D. college students from Dr.
Sallam’s lab, like me, who now reside within the United States or elsewhere, are giving
digital lectures to the following era of undergrads and even main faculty or secondary
faculty college students who’re captivated with fossils or dinosaurs,” he mentioned. “After I
end my Ph.D., I wish to return to Egypt and switch all of the scientific data
I’ve about whale evolution to the following era.”