Evolution: origin of bats unknown (Evolution)

by David Turell , Wednesday, April 22, 2020, 00:17 (1675 days ago) @ David Turell

We've figured out whales series and turtles are being uncovered, but the source ob bats so far is a dead end:

https://www.smithsonianmag.com/science-nature/bats-evolution-history-180974610/?utm_sou...

"...bats are the only mammals to have evolved powered flight, and they’ve been flapping around for tens of millions of years. Where, then, did these flying oddities come from?

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"There are some differences between the oldest bats and their modern relatives. Based upon the ear anatomy of the better-preserved specimens, for example, scientists know that the first bats couldn’t echolocate. They relied on sight, smell and touch to find their meals. While modern bats have a claw only on the equivalent of our thumb, earlier bats kept some of the additional finger claws inherited from their ancestors. A fossil bat dating to about 52 million years ago, dubbed Onychonycteris finneryi in 2008, had claws on all five of its fingers. New technology has added a few details to the early bat story, too. A recent study of coloration in the fossil record found that two 48 million-year-old bats found in Germany were mostly brown.

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"The bats that modern scientists know best lived in places where rapid and delicate preservation entombed the tiny mammals. Some of the bones of Icaronycteris index, one of the earliest known bats and a neighbor of Onychonycteris, are as thin as a human hair. The only reason we know about these bats is that they lived around lakes that favored exceptional preservation; the fine sediment and oxygen-depleted water on the lake bottoms allowed fossils to be buried quickly in an environment scavengers and other decomposers couldn’t reach.

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"Refining our sense of what an early proto-bat might look like is also essential. The current record doesn’t offer many hints. Consider Onychonycteris, one of the oldest known bats featuring some of the most complete remains. While this mammal has more primitive limb proportions and claws on its fingers, says Royal Ontario Museum paleontologist Kevin Seymour, “it is still a bat.” The closest paleontologists can get to understanding this animal is looking at living mouse-tailed bats, Seymour notes, which use a combination of fluttering and gliding to move through the air.

"What came before is only speculative. Bats are mammals, and so the earliest bats were certainly furry. Based on finds such as Onychonycteris, it’s reasonable to propose that bats went through a gliding stage before powered flight, Seymour says, and the first bats probably were insectivores. But that’s about all scientists can say with confidence without a relatively complete fossil to fill in the gap “It will certainly require articulated material,” Seymour says, relatively complete fossils acting as keystones to the tiny fossils of Paleocene and Eocene mammals that may already be resting in museums drawers.

"While experts search for the relevant fossils, other mammals may offer a rough guide of what to expect. Bats may be the only mammals to evolve powered flapping flight, but other mammal species from flying squirrels to a lemur-like creature called the colugo can glide through the air on expanded membranes. The earliest bats probably evolved along a similar route, with some extra skin allowing them to move from tree to tree."

Comment: Probably came from gliding animals, but didn't require the changes whales had to have created. Whals stil defy reasonable Darwinian survival explanations.