The evolution of mammals is redefined by a 280 million-year-old saber-toothed predator fossil.
By extending therapsid origins by millions of years, the discovery of the earliest therapsid
fossil in Mallorca changes our view of animal evolution.
During the middle to late Permian epoch, therapsids—the ancient progenitors of mammals—
were essential to the ecosystems of Earth.
Although their origins have long remained a mystery, these animals eventually gave rise
to mammals in the early Mesozoic.
Important new information on the evolutionary timeline of mammals and their ancient cousins
has been revealed by a ground-breaking discovery made in Mallorca, Spain.
The oldest known gorgonopsian, a kind of therapsid, and potentially the earliest therapsid ever
found is a recently discovered fossil from Mallorca.
The discovery of this fragmentary skeleton on the Mediterranean island has been dated to
between 270 and 280 million years ago, which is tens of millions of years earlier than the
gorgonopsians' original date.
Josep Fortuny, senior author of the study and leader of the Computational Biomechanics and
Evolution of Life History group at the Institut Català de Paleontologia Miquel Crusafont, said,
"It is most likely the oldest gorgonopsian on the globe."
Modern mammals are the only extant members of the varied tetrapod group known as therapsids.
They had a significant impact on terrestrial ecosystems in the late Paleozoic, which is when their
evolutionary roots were established.
Raranimus dashankouensis, which dates to the Roadian stage of the Permian, some 265 million
years ago, is still the earliest known therapsid.
Nonetheless, it has long been hypothesized by phylogenetic analyses that therapsids split off
from its nearest relatives, the sphenacodontid synapsids, some 320 million years ago during
the Pennsylvanian epoch.
This suggested a "ghost lineage," or 40 million years, in the fossil record.
This gap is somewhat filled by the discovery made in Mallorca.
Fossil remains were discovered from a region that was formerly a component of the Permian
supercontinent Pangaea. These remains included pieces of skulls, vertebrae, ribs,
and a well-preserved femur.
Rafel Matamales, the study's primary author and curator of the Museu Balear de Ciències
Naturals, remarks, "The enormous amount of bone remains is astonishing."
"We never imagined that we would discover so many remnants of an animal of this kind
in Mallorca when we began this dig."
The gorgonopsian that was found in Mallorca was a saber-toothed predator
that looked very different from a medium-sized dog but had a similar structure.
Co-author of the study and Field Museum curator Ken Angielczyk says,
"If you saw this animal going down the street, it might seem a little bit like a husky,
but it wouldn’t be exactly right."
"It possessed long, blade-like canine teeth, yet it lacked fur and dog-like ears."
The gorgonopsian's position as a top predator in its environment is demonstrated by these
saber teeth. Long-held beliefs on the rate and location of therapsid evolution are called
into question by this discovery, which also adds to the known timeframe of gorgonopsians.
In fewer than 10 million years after Olson's Extinction, a lesser-known mega
extinction event that came before the Permian-Triassic extinction,
the fossil indicates that key therapsid families underwent fast diversification.
The early history of therapsids has often been masked by biases in geographic sampling.
The Cis-Urals of southern Africa and Russia,
which correspond to northern and southern paleotemperate latitudes, are where the majority
of Permian therapsid fossils have been discovered.
Conversely, there are not many conclusive therapsid fossils from the early Permian deposits
of North America and Europe, which correlate to paleotropical habitats.
A vital connection between these areas is made possible by the discovery in Mallorca,
which also sheds light on the spatiotemporal dynamics of therapsid evolution.
Therapsids' distinctive anatomical traits, which unite reptiles and mammals, are what give
them evolutionary relevance.
Early therapsids had traits including jawbone features that would eventually develop into
the middle ear bones of mammals and a hole on the sides of their heads for the attachment
of jaw muscles.
Angielczyk observes that "gorgonopsians are more closely linked to mammals than to any
other living species."
Gorgonopsians are closely linked to the species that eventually gave rise to mammals,
while not being their direct ancestors.
The discovery in Mallorca serves as a reminder of the Permian therapsids' quick diversification.
Researchers are now able to establish a more accurate date for therapsid development thanks
\to emerging statistical models like relaxed clock models.
According to these scenarios, therapsids underwent an evolutionary radiation following
Olson's Extinction, which resulted in the creation of all major therapsid clades in an exceptionally
brief amount of time.
This discovery is very important for comprehending the origins of mammals.
According to Angielczyk, "there existed an age of ancient mammal ancestors before the time of
dinosaurs."
"Compared to what we currently conceive of as mammals, the majority of those ancient mammal
relatives appeared very different.
However, they were incredibly varied and served a wide range of ecological functions.
Findings such as the one in Mallorca contribute to the completion of the puzzle that
is the fossil record.
The gorgonopsian fossil highlights the significance of paleotropical areas in early Permian
ecosystems in addition to extending the known history of therapsids.
Our knowledge of the evolutionary processes leading to modern mammals will only increase
as scientists investigate these areas further and use more sophisticated statistical methods.
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