Oldest species of a marine mollusc discovered

Feb 22, 2011
These are two specimen of Polyconites hadriani. Credit: Eulàlia Gili et al.

An international research team, with Spanish participation, has discovered a new species of mollusc, Polyconites hadriani, in various parts of the Iberian Peninsula. The researchers say this species, which is the oldest in its genus, adapted to the acidification of the oceans that took place while it was in existence. This process could now determine the evolution of modern marine systems.

The new Polyconites hadriani, which was discovered in 2007, has been crowned the oldest in the Polyconites genus of the family Polyconitidae (rudists), a kind of extinct sea mollusc. To date, scientists had thought that the oldest mollusc in this genus was Polyconites verneuili.

"P. hadriani is similar in shape to P. verneuili, but it is smaller (with a 30mm smaller diameter), and with a thinner layer to its shell (around 3mm difference)", Eulàlia Gili, one of the authors of the study and a researcher at the Department of Geology of the Autonomous University of Barcelona (UAB), tells SINC.

The new species was found in several parts of the – in the Maestrat basin, the Vasco-Cantábrica basin, to the south of the Lusitania basin and in the Cordillera Prebética mountain range, "where it accumulated in dense conglomerations along the banks of the carbonate marine platforms of the Lower Aptian period (114 million years ago)", says Gili.

"This recognition of P. hadriani resolves the lengthy uncertainty about the identity of these polyconitids of the Lower Aptian", the researcher says in the study, which has been published in the Turkish Journal of Earth Sciences.

Adaptation to acidification of the oceans

Gili says the Lower Aptian was a convulsive period, during which significant climate change took place. P. hadriani existed at the time when the first oceanic anoxic event of the Cretaceous took place (between 135 and 65 million years ago). This event was characterised by a "lack of oxygen on the seabed, which led to the mass burial of organic carbon and climate cooling".

"The thicker calcite layer of the shell of this new species compared with that of its predecessor (of the Horiopleura genus), could have helped it adapt better to life in colder waters, which were more acidic due to the increased solubility of atmospheric CO2", the geologist explains.

The researcher adds: "The response of these rudists to acidification could apply to the future of today's marine ecosystems, above all among those kinds of organisms that form their shells or skeletons from calcium carbonate".

Explore further: Unique entry complex discovered at Herodian Hilltop Palace

More information: Peter W. Skelton, Eulàlia Gili, Telm Bover-Arnal, Ramon Salas, Josep Anton Moreno-Edmar. "A New Species of Polyconites from the Lower Aptian of Iberia and the Early Evolution of Polyconitid Rudists". Turkish Journal of Earth Sciences, Vol. 19, 2010. doi:10.3906/yer-0901-7

Provided by FECYT - Spanish Foundation for Science and Technology

3.5 /5 (2 votes)
add to favorites email to friend print save as pdf

Related Stories

Oldest fossils found in Cordillera Betica mountain range

Dec 13, 2010

Spanish researchers have found fossils of Ordovician conodonts dating to between 446 and 444 million years ago for the first time in the western Mediterranean. The discovery of these very primitive marine ...

Two new plants discovered in Spain

Feb 15, 2011

Just when everyone thought that almost every plant species on the Iberian Peninsula had been discovered, Spanish researchers have discovered Taraxacum decastroi and Taraxacum lacianense, two dandelions fr ...

Ocean acidification threatens cold-water coral ecosystems

Apr 03, 2006

Corals don't only occur in warm, sun-drenched, tropical seas; some species are found at depths of three miles or more in cold, dark waters throughout the world's oceans. Some cold-water coral reefs are home to more than 1,300 ...

Extinct rodent species discovered

Jul 28, 2009

An international team of scientists has discovered an extinct rodent species, based on fossil tooth remains found in Alborache, Valencia. Eomyops noeliae, from the Eomyidae family, represents the oldest fi ...

Recommended for you

Ancient clay seals may shed light on biblical era

Dec 20, 2014

Impressions from ancient clay seals found at a small site in Israel east of Gaza are signs of government in an area thought to be entirely rural during the 10th century B.C., says Mississippi State University archaeologist ...

Digging up the 'Spanish Vikings'

Dec 19, 2014

The fearsome reputation of the Vikings has made them the subject of countless exhibitions, books and films - however, surprisingly little is known about their more southerly exploits in Spain.

Short-necked Triassic marine reptile discovered in China

Dec 17, 2014

A new species of short-necked marine reptile from the Triassic period has been discovered in China, according to a study published December 17, 2014 in the open-access journal PLOS ONE by Xiao-hong Chen f ...

User comments : 0

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.