Featured Research

from universities, journals, and other organizations

New fossil find pinpoints the origin of jaws in vertebrates

Date:
June 11, 2014
Source:
University of Cambridge
Summary:
A major fossil discovery in Canada sheds new light on the development of the earliest vertebrates, including the origin of jaws, the first time this feature has been seen so early in the fossil record.

Left: This is an illustration of Metaspriggina swimming. Drawing by: Marianne Collins. Conway Morris and Caron. Right: This is a fossil of Metaspriggina from Marble Canyon -- head to the left with two eyes, and branchial arches at the top. Photo by: Jean-Bernard Caron ROM.
Credit: Left: Drawing by Marianne Collins / Copyright Conway Morris and Caron. Right: Photo by Jean-Bernard Caron / Copyright ROM.

A major fossil discovery in Canada sheds new light on the development of the earliest vertebrates, including the origin of jaws, the first time this feature has been seen so early in the fossil record.

A key piece in the puzzle of the evolution of vertebrates has been identified, after the discovery of fossilised fish specimens, dating from the Cambrian period (around 505 million years old), in the Canadian Rockies. The fish, known as Metaspriggina, shows pairs of exceptionally well-preserved arches near the front of its body. The first of these pairs, closest to the head, eventually led to the evolution of jaws in vertebrates, the first time this feature has been seen so early in the fossil record.

Fish fossils from the Cambrian period are very rare and usually poorly preserved. This new discovery shows in unprecedented detail how some of the earliest vertebrates developed -- the starting point of a story which led to animals such as later fish species, but also dinosaurs and mammals such as horses and even ourselves. The findings are published in the 11 June edition of the journal Nature.

Fossils of Metaspriggina were recovered from several locations including the Burgess Shale site in Canada's Rocky Mountains, one of the richest Cambrian fossil deposits in the world. These fossils shed new light on the Cambrian 'explosion', a period of rapid evolution starting around 540 million years ago, when most major animal phyla originated.

Previously, only two incomplete specimens of Metaspriggina had been identified. During expeditions conducted by the Royal Ontario Museum in 2012, 44 new Burgess Shale fossils were collected near Marble Canyon in Kootenay National Park in British Columbia, which provide the basis for this study. Researchers from the University of Cambridge and the Royal Ontario Museum/University of Toronto used these fossils, along with several more specimens from the eastern United States, to reclassify Metaspriggina as one of the first vertebrates.

The fossils, which date from 505 million years ago, also show clearly for the first time how a series of rod-like structures, known as the gill or branchial arches, were arranged in the earliest vertebrates. These arches have long been known to have played a key role in the evolution of vertebrates, including the origin of jaws, and some of the tiny bones in the ear which transmit sound in mammals. Until now, however, a lack of quality fossils has meant that the arrangement of these arches in the first vertebrates had been hypothetical.

Vertebrates first appear in the fossil record slightly earlier than these finds, but pinpointing exactly how they developed is difficult. This is because fossils of such animals are rare, incomplete and open to varying interpretations, as they show soft tissues which are difficult to identify with complete certainty.

The new fossils of Metaspriggina are remarkably well-preserved. The arrangement of the muscles shows these fish were active swimmers, not unlike a trout, and the animals saw the world through a pair of large eyes and sensed their surrounding environment with nasal structures.

"The detail in this Metaspriggina fossil is stunning," said lead author Professor Simon Conway Morris of Cambridge's Department of Earth Sciences. "Even the eyes are beautifully preserved and clearly evident."

But it is the branchial arches which makes this discovery so important. Previously, they were thought to exist as a series of single arches, but Metaspriggina now shows that they in fact existed in pairs. The anteriormost pair of arches is also slightly thicker than the remainder, and this subtle distinction may be the very first step in an evolutionary transformation that in due course led to the appearance of the jaw. "Once the jaws have developed, the whole world opens," said Professor Conway Morris. "Having a hypothetical model swim into the fossil record like this is incredibly gratifying."


Story Source:

The above story is based on materials provided by University of Cambridge. The original story is licensed under a Creative Commons Licence. Note: Materials may be edited for content and length.


Journal Reference:

  1. Simon Conway Morris, Jean-Bernard Caron. A primitive fish from the Cambrian of North America. Nature, 2014; DOI: 10.1038/nature13414

Cite This Page:

University of Cambridge. "New fossil find pinpoints the origin of jaws in vertebrates." ScienceDaily. ScienceDaily, 11 June 2014. <www.sciencedaily.com/releases/2014/06/140611131743.htm>.
University of Cambridge. (2014, June 11). New fossil find pinpoints the origin of jaws in vertebrates. ScienceDaily. Retrieved July 30, 2014 from www.sciencedaily.com/releases/2014/06/140611131743.htm
University of Cambridge. "New fossil find pinpoints the origin of jaws in vertebrates." ScienceDaily. www.sciencedaily.com/releases/2014/06/140611131743.htm (accessed July 30, 2014).

Share This




More Fossils & Ruins News

Wednesday, July 30, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Rodents Rampant in Gardens Around Louvre

Rodents Rampant in Gardens Around Louvre

AP (July 29, 2014) Food scraps and other items left on the grounds by picnickers brings unwelcome visitors to the grounds of the world famous and popular Louvre Museum in Paris. (July 29) Video provided by AP
Powered by NewsLook.com
London's Famed 'Gherkin' Goes on Sale for 650 Mln

London's Famed 'Gherkin' Goes on Sale for 650 Mln

AFP (July 29, 2014) London's "Gherkin" office tower, one of the landmarks on the British capital's skyline, went on sale for about 650 million ($1.1 billion, 820 million euros) on Tuesday after being placed into receivership. Duration: 00:36 Video provided by AFP
Powered by NewsLook.com
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Tourists Disappointed to Find Rome Attractions Under Restoration

Tourists Disappointed to Find Rome Attractions Under Restoration

AFP (July 26, 2014) Tourists visiting Italy at the peak of the summer season are disappointed to find some of Rome's most famous attractions being restored and offering limited access. Duration: 01:01 Video provided by AFP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins