New Ostracod Species Discovered In Ancient Fossil Record
December 12, 2012

Scientists Discover Ancient Fossils Of A New Ostracod Species

Brett Smith for - Your Universe Online

A team of British and American scientists have discovered the fossils of a tiny new species of animal in 425-million-year-old rocks located along the England-Wales border, according to the their report published in the journal Proceedings of The Royal Society B.

The new species is an ostracod — a small crustacean related to crabs, lobsters and shrimps — and was exceptionally well preserved. Its fossil included a complete shell exterior as well as its interior soft parts, including the body, limbs, eyes, gills and alimentary system — a rare find in the fossil record.

"The two ostracod specimens discovered represent a genus and species new to science, named Pauline avibella,” said lead author David Siveter of the University of Leicester´s Department of Geology. “The genus is named in honor of a special person and avibella means 'beautiful bird', so-named because of the fancied resemblance of a prominent feature of the shell to the wing of a bird."

"Ostracods are the most abundant fossil arthropods, occurring ubiquitously as bivalved shells in rocks of the last 490 million years, and are common in most water environments today,” he added.

Siveter explained that the fossil is particularly important since it is one of only a few ostracod fossils ever recovered in which the soft tissue of the animal´s body was preserved during fossilization. Yet despite the exquisite preservation of the specimen, he says that the creature still presents a challenge for taxonomists trying to figure out how to classify the newly discovered species.

“Its assignment to a particular group of ostracods based on knowledge of its biology is at odds with its shell form, thus urging caution in interpreting the classification of fossil ostracods based on shell characters alone."

The scientists were able to create a virtual three-dimensional representation of the fossil by grinding the fossils down, layer by layer, and photographing it at each step in the process. The approximately 500 slices per specimen were then pieced together digitally to create a full computer rendering.

The modeling allowed the scientists to better understand the anatomy of the new species, which would have otherwise been difficult to do based only on the animal´s exterior.

"It is exciting to discover that a common group of fossils that we thought we knew a lot about may well have been hood-winking us as to their true identity, which we now realize because we have their beautifully fossilized soft-parts. A case of a 'wolf in sheep's clothing',” said Siveter.

"The preservation of soft-parts of animals is a very rare occurrence in the fossil record and allows unparalleled insight into the ancient biology, community structure and evolution of animals — key facts that that would otherwise be lost to science,” he added. “The fossils known from the Herefordshire site show soft-part preservation and are of global importance."

The rocks that contained the new ostracod fossil date back to the Silurian period of geological time. During this period, much of the U.K. was covered by ocean and the area itself was located in southerly, subtropical latitudes. The fossils of the sea creatures living there were created by a fall of volcanic soot and ash that preserved them for millions of years. According to the report, the ostracods were living between 150 and 200 meters below sea level when they were covered by the volcano.