Domestic cats sometimes disappear days before that, in general, they become safe and healthy. But this relatively brief disappearance is nothing compared to the “cat gap” – a period in the fossil record from about 25 million to 18.5 million years ago when cats and feline-like species appear to have disappeared. “disappeared” from North America for almost 7 years. millions of years.
So, what is the reason for this gap? It’s just another example of cat’s confused behaviorsuch as their inclination sit in the box or run around at random explosive speed without the slightest provocation? Are they bored of North America? Could it all be a misunderstanding?
Various theories have been put forward, from cats and feline species moving away from North America in search of better places to hunt, to being affected by global cooling from volcanic eruptions. (caused the mass extinction event at different time intervals) to conditions at the time not suitable for fossilization.
However, according to Carlo Meloro, a vertebrate paleontologist at Liverpool John Moores University in the UK, only so much can be concluded based on current knowledge and evidence. As for those ideas, they shouldn’t be seen as anything other than conjecture, according to Meloro.
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“It’s all conjecture,” he said. “If specific geological activities preclude cats from being found in North America in deposits during this period, that doesn’t necessarily mean they weren’t there.” Meloro emphasized that “a combination of factors may have created the cat gap,” which could include “climate changecompetition with other species and ecological displacement. “
David Polly, a paleontologist at Indiana University Bloomington, agrees. “The absence of cats cannot be explained by [the] However, Polly believes there may be a clearer explanation, and it is an explanation supported by Meloro.
Polly told Live Science: “The exclusion of cats from North America is, to some extent, simply a coincidence related to the extinction of one cat breed group and the inability of another group to invade. enter North America. In other words, the “gap” can be real.
Note the distance
Before the feline gap, Meloro explained, there are three taxonomic families of cats: Nimravidae, Barbourofelidae, and Felidae, all of which fall under the taxon Carnivora.
The Nimravidae, commonly known as the “false-toothed cats”, and the cat-like carnivores Barbourofelidae, both now extinct, shared features similar to those of the modern domestic cat. Although biologically similar, they were not directly related to today’s cats. Felidae, on the other hand, are.
Polly said: “A true cat, which is a species closely related to or ancestral to living felts, including cats, lion, Many tigers and services. ”
These three taxa, although similar in appearance and genetic makeup, did not all inhabit the same regions at the same time. According to both Meloro and Polly, this point is important for understanding cat distance.
“In North America, the family Nimravidae can be found during the Oligocene and 28.7 million years ago, so they appear to have disappeared just before the cat gap,” Meloro said. “Barbourofelidae, meanwhile, arrived in North America after the cat gap, with members of the genus Barbourofelis appear between 11.5 [million] and 9.8 million years ago. “
The demise of the nimravids, according to Polly, “determined the beginning of the feline gap.” He went on to suggest that the species’ extinction was the result of North American ecosystems shifting towards becoming “difficult to function as a super carnivore.” Polly added that, during this time, herbivores – probable prey of the nimravids – had developed “specializations for moving faster over great distances,” which would have made animals super eating meat is much harder to find food.
So, according to Meloro, one “cat-like” species was already extinct at the time of the cat’s isolation, and another had yet to migrate to North America. But what about the Felidae, the real relatives of today’s cats?
“The migration of bugs to North America requires a land connection with Eurasia and the ecosystems where cats can thrive,” Polly said. “Sea levels rise and fall during the Miocene [23.03 million to 5.3 million years ago]and cats may have crossed North America after that, possibly across Siberia to Alaska.
Meloro added: “The availability and viability of the land bridge requires both low sea levels and appropriate ecosystems within the land bridge area. This may also be how Barbourofelidae came to reside in North America.
As a result, very few fossils of cats or feline-like species have been discovered in North America during the “cat gap”, Polly believes, because there simply haven’t been any fossils to be found.
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However, even if there are North American cat fossils from the “cat gap” that are ready and waiting to be discovered, there is no guarantee they will be found in large numbers, according to one expert. other family.
David Martill, a paleontologist from the University of Portsmouth in the UK, has suggested that the lack of Felidae fossils from this period could be the result of very few people trying to find them. “How many people are out hunting for cat fossils?” he say.
Martill also points out that such fossil gaps are common. “The fossil record is extremely patchy,” he said. “Stratigraphy [rock layer] The record fills the time gap. Indeed, there are more gaps than there are records. “
Polly admits that, in theory, the lack of fossil hunters could explain the feline gap.
“The fossil record does not uniformly sample all of North America, so it is possible that nimravids existed as late as 23 million years in some corners of the continent, or that felids arrived in some areas before 17 million years,” he said. prior to”.
However, he was not entirely convinced.
“The fossil record of mammals, including carnivores, is very good in North America during the male cat era,” Polly said. “We have hundreds to thousands of fossil sites in that time period, with tens of thousands to perhaps millions of fossils.”
Originally published on Live Science.
https://www.livescience.com/why-cat-gap-north-america-fossils Did cats really disappear from North America for 7 million years?