Phallus-shaped fossil pushes record of enteropneusts back 200 million years

Related Articles

Related Articles

Two individuals of Harrimania planktophilus, a modern enteropneust (harrimaniid) worm. Proboscis to the left. Total length of a relaxed and uncoiled animal is approximately 32 mm. Photo: C.B. Cameron, Université de Montréal

Christopher Cameron of the University of Montreal’s Department of Biological Sciences and his colleagues have unearthed a major scientific discovery – a strange phallus-shaped creature they found in Canada’s Burgess Shale fossil beds, located in Yoho National Park. The fossils were found in an area of shale beds that are 505 million years old.

Their study, to be published online in the journal Nature on March 13, 2013, confirms Spartobranchus tenuis is a member of the acorn worms group which are seldom-seen animals that thrive today in the fine sands and mud of shallow and deeper waters.  Acorn worms are themselves part of the hemichordates, a group of marine animals closely related to today’s sea stars and sea urchins. “Unlike animals with hard parts including teeth, scales and bones, these worms were soft-bodied, so their fossil record is extremely rare,” said author Dr. Chris Cameron of the University of Montreal.  “Our description of Spartobranchus tenuis, a creature previously unknown to science, pushes the fossil record of the enteropneusts back 200 million years to the Cambrian period, fundamentally changing our understanding of biodiversity from this period.”

 

Since their discovery in the 19th-century, some of the biggest questions in hemichordate evolution have focused on the group’s origins and the relationship between its two main branches: the enteropneusts and the pterobranchs, including graptolites. “One of the big punchlines from my graduate work, was molecular evidence that enteropneusts and pterobranchs are closely related” said Cameron, a specialist on the taxonomy, evolution and biogeography of hemichordates.

“It’s astonishing how similar Spartobranchus tenuis fossils are to modern day acorn worms, except that they also formed fibrous tubes.”  The tubes provide a key missing link that connects the two main hemichordate groups. “The explosive radiation of graptolites in the Paleozoic planktonic ecosystems is known only from the diversity of their tubes. Our findings suggest that the tubes were lost in the lineage leading to modern day enteropneusts, but elaborated on in graptolites and retained to the present day in pterobranchs” added Cameron.

Hemichordates also share many of the same characteristics as chordates – a group of animals that includes humans – with the name hemichordate roughly translating to ‘half a chordate.’

 “Work from my lab has shown that enteropneusts filter feed using a pharynx perforated with gill slits, just like the invertebrate chordates” added Cameron. Spartobranchus tenuisprobably fed on small particles of matter filtered from the seawater. “There are thousands of specimens at the Walcott Quarry in Yoho National Park, so it’s possible Spartobranchus tenuis may have played an important role in moving carbon from the water column to the sediment in the early Burgess Shale environment” said Cameron.

Detailed analysis suggests Spartobranchus tenuis had a flexible body consisting of a short proboscis, collar and narrow elongate trunk terminating in a bulbous structure, which may have served as an anchor. The largest complete specimens examined were 10 centimetres long with the proboscis accounting for about half a centimetre. A large proportion of these worms was preserved in tubes, of which some were branched, suggesting the tubes were used as a dwelling structure.

Other members of the Spartobranchus tenuis research team are lead author Jean-Bernard Caron of the Royal Ontario Museum and Simon Conway Morris of the University of Cambridge.

Contributing Source : Université de Montréal

HeritageDaily : Archaeology News : Archaeology Press Releases

Download the HeritageDaily mobile application on iOS and Android

More on this topic

LATEST NEWS

Ancient Mosaic Criticises Christianity

An ancient mosaic from a 4th-century house in the centre of the ancient city of Paphos in Cyprus, was a 'pictorial' criticism of Christianity according to experts.

Geoscience: Cosmic Diamonds Formed During Gigantic Planetary Collisions

It is estimated that over 10 million asteroids are circling the Earth in the asteroid belt. They are relics from the early days of our solar system, when our planets formed out of a large cloud of gas and dust rotating around the sun.

Vettuvan Koil – The Temple of the Slayer

Vettuvan Koil is a rock-cut temple, located in Kalugumalai, a panchayat town on the ancient trade routes from Kovilpatti to courtallam, in the southern Indian state of Tamil Nadu.

The Testimony of Trees: How Volcanic Eruptions Shaped 2000 Years of World History

Researchers have shown that over the past two thousand years, volcanoes have played a larger role in natural temperature variability than previously thought, and their climatic effects may have contributed to past societal and economic change.

Sentinels of Ocean Acidification Impacts Survived Earth’s Last Mass Extinction

Two groups of tiny, delicate marine organisms, sea butterflies and sea angels, were found to be surprisingly resilient--having survived dramatic global climate change and Earth's most recent mass extinction event 66 million years ago.

The Venerable Ensign Wasp, Killing Cockroaches For 25 million Years

An Oregon State University study has identified four new species of parasitic, cockroach-killing ensign wasps that became encased in tree resin 25 million years ago and were preserved as the resin fossilized into amber.

Modern Humans Reached Westernmost Europe 5,000 Years Earlier Than Previously Known

Modern humans arrived in the westernmost part of Europe 41,000 - 38,000 years ago, about 5,000 years earlier than previously known, according to Jonathan Haws, Ph.D., professor and chair of the Department of Anthropology at the University of Louisville, and an international team of researchers.

Akrotiri – The Ancient Town Buried by a Volcano

Akrotiri is an archaeological site and a Cycladic Bronze Age town, located on the Greek island of Santorini (Thera) near the present-day village of Akrotiri (for which the prehistoric site is named).

Popular stories

The Secret Hellfire Club and the Hellfire Caves

The Hellfire Club was an exclusive membership-based organisation for high-society rakes, that was first founded in London in 1718, by Philip, Duke of Wharton, and several of society's elites.

Port Royal – The Sodom of the New World

Port Royal, originally named Cagway was an English harbour town and base of operations for buccaneers and privateers (pirates) until the great earthquake of 1692.

Matthew Hopkins – The Real Witch-Hunter

Matthew Hopkins was an infamous witch-hunter during the 17th century, who published “The Discovery of Witches” in 1647, and whose witch-hunting methods were applied during the notorious Salem Witch Trials in colonial Massachusetts.

Did Corn Fuel Cahokia’s Rise?

A new study suggests that corn was the staple subsistence crop that allowed the pre-Columbian city of Cahokia to rise to prominence and flourish for nearly 300 years.