Ancient fish fossils reveal origin of the vertebrate skeleton

New X-ray images of ancient fish fossils have helped scientists solve a 160-year-old mastery about the origins of the vertebrate skeleton.

Heterostracans are a group of fossil fishes that lived 400 million years ago. The heterostracan fossil record has offered the oldest evidence of mineralized skeletons among vertebrates. But scientists have struggled to determine what type of tissue heterostracan skeleton's were made of.

Bone, cartilage, dentine and enamel all mineralize as they develop, gaining strength and rigidity. But millions of years later, these fossilized tissues are difficult to distinguish -- until now.

Scientists at the universities of Manchester and Bristol used CT scanning technology, featuring high energy X-rays, to image the internal structure of heterostracan skeletons. The ancient fish built their skeletons using an entirely unique tissue.

"Heterostracan skeletons are made of a really strange tissue called aspidin," Manchester researcher Joseph Keating said in a news release. "It is crisscrossed by tiny tubes and does not closely resemble any of the tissues found in vertebrates today. For a 160 years, scientists have wondered if aspidin is a transitional stage in the evolution of mineralized tissues."

The hi-def images -- detailed in the journal Nature Ecology and Evolution -- suggest the aspidin skeleton's tiny tubes were once filled with bundles of collagen fibers.

"These findings change our view on the evolution of the skeleton," said Bristol researcher Phil Donoghue. "Aspidin was once thought to be the precursor of vertebrate mineralized tissues. We show that it is, in fact, a type of bone, and that all these tissues must have evolved millions of years earlier."

Related Links
Explore The Early Earth at TerraDaily.com

Tweet

Thanks for being there;
We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain.

With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords.

Our news coverage takes time and effort to publish 365 days a year.

If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.

SpaceDaily Monthly Supporter
$5+ Billed Monthly

paypal only

SpaceDaily Contributor
$5 Billed Once

credit card or paypal

Paleontologists discover largest dinosaur foot to date
Washington DC (SPX) Jul 30, 2018
As it turns out, "Bigfoot" was a dinosaur - a giant, plant-eating one. A new study based on fossils excavated in Wyoming reveals the largest dinosaur foot ever found and identifies it as a brachiosaur, a type of sauropod dinosaur that was among the largest land animals on Earth. The work, published today in the journal PeerJ, also confirms that 150 million years ago brachiosaurs called a huge swath of North America home. "There are tracks and other incomplete skeletons from Australia and Argentina ... read more