Nearly 63% of Afro-Arabian mammalian species went extinct roughly 30 million years in the past (Oligocene epoch), after Earth’s local weather shifted from swampy to icy.
In a brand new research, University of Salford’s Dr. Dorien de Vries and colleagues checked out fossils of 5 mammal teams: (i) a gaggle of extinct carnivores referred to as hyaenodonts; two rodent teams: (ii) the anomalures (scaly-tail squirrels) and (iii) the hystricognaths (a gaggle that features porcupines and bare mole rats); and two primate teams: (iv) the strepsirrhines (lemurs and lorises) and (v) the anthropoids (apes and monkeys).
By gathering knowledge on a whole bunch of fossils from a number of websites in Africa, they had been capable of construct evolutionary timber for these teams, pinpointing when new lineages branched out and time-stamping every species’ first and final recognized appearances.
Their outcomes present that every one 5 mammal teams suffered large losses across the Eocene-Oligocene boundary.
“It was a real reset button. After a few million years, these groups start popping up again in the fossil record, but with a new look,” Dr. de Vries mentioned.
“The fossil species that re-appear later in the Oligocene, after the big extinction event, are not the same as those that were found before.”
“It’s very clear that there was a huge extinction event, and then a recovery period,” mentioned Dr. Steven Heritage, a researcher at Stony Brook University and the Duke Lemur Center Museum of Natural History.
The proof is within the enamel of those animals. Molar enamel can inform quite a bit about what a mammal eats, which in turns tells quite a bit about their setting.
The rodents and primates that reappeared after just a few million years had totally different enamel. These had been new species, who ate various things, and had totally different habitats.
“We see a huge loss in tooth diversity, and then a recovery period with new dental shapes and new adaptations,” Dr. de Vries mentioned.
“Extinction is interesting in that way. It kills things, but it also opens up new ecological opportunities for the lineages that survive into this new world,” mentioned Dr. Matt Borths, curator of the Duke Lemur Center Museum of Natural History.
This decline in variety adopted by a restoration confirms that the Eocene-Oligocene boundary acted as an evolutionary bottleneck: most lineages went extinct, however just a few survived.
Over the following a number of tens of millions of years, these surviving traces diversified.
“In our anthropoid ancestors, diversity bottoms out to almost nothing around 30 million years ago, leaving them with a single tooth type,” mentioned Professor Erik Seiffert, a researcher within the Keck School of Medicine on the University of Southern California, the Duke Lemur Center Museum of Natural History, and the Department of Mammalogy on the Natural History Museum of Los Angeles County.
“That ancestral tooth shape determined what was possible in terms of later dietary diversification.”
“There’s an interesting story about the role of that bottleneck in our own early evolutionary history.”
“We came pretty close to never existing, if our monkey-like ancestors had gone extinct 30 million years ago. Luckily they didn’t.”
The research was revealed within the journal Communications Biology.
D. de Vries et al. 2021. Widespread lack of mammalian lineage and dietary variety within the early Oligocene of Afro-Arabia. Commun Biol 4, 1172; doi: 10.1038/s42003-021-02707-9