Discovered to a greater extent than than one-half a century agone inwards Republic of Kenya as well as sitting inwards museum storage always since, the roughly 20-million-year-old fossil Propotto leakeyi was long classified every bit a fruit bat.
 |
| Fossilized fragments of primate jaws as well as teeth from Africa are changing what researchers thought they knew about when lemurs made it to Madagascar. Shown hither is 20-million-year-old Propotto leakeyi [Credit: Duke SMIF] |
In a written report published inwards the periodical Nature Communications, researchers accept re-examined Propotto's fossilized remains as well as suggest that the foreign creature wasn't a bat, but an ancient relative of the aye-aye, the bucktoothed nocturnal primate that represents i of the earliest branches of the lemur identify unit of measurement tree.
The reassessment challenges a long-held sentiment that today's 100-some lemur species descended from ancestors that made their agency to Republic of Madagascar inwards a unmarried moving ridge to a greater extent than than sixty 1000000 years ago, becoming some of the outset mammals to colonize the island.
Instead, the written report lends back upward to the thought that 2 lineages of lemurs split upward inwards Africa earlier coming to Madagascar. One lineage eventually led to the aye-aye, as well as the other to all other lemurs. There are no lemurs left on mainland Africa. These ancestors as well as then colonized Republic of Madagascar independently, as well as millions of years afterwards than in i trial believed.
"One implication is that lemurs accept had a much less extensive evolutionary history on Republic of Madagascar than was previously thought," said written report co-author Erik Seiffert, professor of anatomy at the University of Southern California.
When Propotto was outset described inwards the 1960s, experts didn't concord nearly what they were looking at. They didn't accept a lot to instruct on: but 3 lower jaw bones, each barely an inch long, as well as a handful of teeth less than 3 millimeters across.
 |
| These fossils could rewrite the source story of Madagascar’s lemurs. Plesiopithecus teras, left, lived 34 1000000 years ago in Egypt. Propotto leakeyi, right, lived twenty 1000000 years agone inwards Republic of Kenya [Credit: Duke SMIF] |
For nearly one-half a century the creature's identity appeared to accept been settled, until 2016, when some other paleontologist, the belatedly Gregg Gunnell of Duke University, began taking a fresh hold back at the fossil. To Gunnell's eye, the creature's hind teeth were to a greater extent than reminiscent of a primate than a bat. He also noted the stump of a broken front end tooth, but visible inwards cross section, which would accept jutted out from its oral cavity similar a dagger -- a trait exclusively known inwards aye-ayes, the exclusively living primates amongst rodent-like teeth.
"Gregg wrote to us as well as said, 'Tell me I'm crazy,'" Seiffert said.
To verify Propotto's identify inwards the primate identify unit of measurement tree, Seiffert as well as Steven Heritage of Duke's Division of Fossil Primates analyzed to a greater extent than than 395 anatomical features as well as 79 genes for 125 mammal species, living as well as extinct.
With assist from Doug Boyer, associate professor of evolutionary anthropology at Duke, the squad also compiled microCT scans of the lower molars of 42 living as well as extinct mammal groups, including bats, treeshrews as well as primates. They as well as then used a estimator plan to compare the bumps, pits as well as ridges on the scans of Propotto's teeth to those of other animals.
The researchers institute that Propotto shared a issue of features amongst a similarly buck-toothed primate that lived 34 1000000 years agone inwards Arab Republic of Egypt called Plesiopithecus, as well as that both were ancient relatives of the aye-aye.
 |
| New analysis shows that fossilized remains institute inwards Africa belonged to ancient relatives of the aye-aye [Credit: David Haring, Duke Lemur Center] |
The findings suggest they arrived around the same fourth dimension every bit other mammals, such every bit rodents, Malagasy mongooses as well as hedgehog- as well as shrew-like animals called tenrecs. Frogs, snakes as well as lizards may accept made the trip around the same time.
Lemurs can't swim, thus some scientists hypothesize that the small-bodied creatures crossed the 250-mile-wide channel that lies betwixt Africa as well as Republic of Madagascar after beingness swept out to body of body of water inwards a storm, past times belongings on to tree limbs or floating mats of vegetation earlier lastly washing ashore.
But if the arrival were to a greater extent than recent, they mightiness accept had a shorter distance to travel, thank you lot to lower body of body of water levels when the Antarctic H2O ice canvass was much larger.
"It's possible that lemurs weren't inwards Republic of Madagascar at all until perchance the Miocene," every bit late every bit 23 1000000 years ago, Boyer said.
"Some of the lowest body of body of water levels were also during this time," Heritage said.
Either way, "the fossils nation us something nosotros never could accept guessed from the deoxyribonucleic acid bear witness nearly the history of lemurs on Madagascar," Boyer said.
Author: Robin A. Smith | Source: Duke University [August 21, 2018]
Buat lebih berguna, kongsi:
