Monday, 29 September 2014

New fossil discovery.



Hello all sorry for the massive break in between posts I have been really busy with work and volunteering and time has rather evaded me ! I hope you have all had a good summer especially with the weather  continuing to surpass expectations. I recently read about a fascinating new fossil discovery which makes up the content of this post. I hope you enjoy the blog.

First insect fossils recorded in Late Kimmeridgian marine limestones.

Field studies taking place between 2012 and 2013 led by French researchers and aided by two teams of amateur scientists the Société des Naturalistes et Archéologues de l'Ain and the Group 'Sympetrum Recherche et Protection des Libellules' in Orbagnoux, France on the Late Kimmeridgian marine limestone’s have recorded a historical first recent publications have revealed. The marine limestones are well known for their abundance of fish and terrestrial fauna. There had however only been one previous terrestrial based discovery before the findings of this latest research came to light, when plant remains had been found to of been transported in lagoons. As a result, this is the first occasion where insects and evidence of insect activity have been recorded in the area.
The discovery of a 6mm specimen of the species now known as Gallomesovelia grioti of the basal mesoveliidae family comprising of water treaders make it the oldest record to date of gerromorpha bugs . Modern water treaders have a predatory nature, living in humid locations with either a terrestrial or freshwater lifestyle. It has been theorised that Gallomesovelia grioti potentially could have lived in the near proximity of sea margins or as some modern species of mesoveliidae can in brackish parts of lagoons. Characteristics of gerromorpha species include large compound eyes and a rounded head not conversed transversely.
Also discovered was evidence of damage to zamite leaves as a result of insect feeding behaviour. Evidence of this activity in the fossil record in the late Jurassic is rare in comparison to records from the Triassic and Lower Cretaceous period and as such every recording is particularly welcomed. Signs of insect activity on zamite leaves illustrate there would have been a significant level of insect diversity and insect fauna it would appear was not restricted to aquatic or subaquatic bugs. Fossil evidence found in the limestone provides evidence of terrestrial insects utilising emerged lands with Jurassic lagoons in close proximity. The majority of the fieldworks findings however consisted of ammonites, bivalvia, shrimps, isopods and fish. These recent studies it would suggest show evidence of close terrestrial biota.
As a result of the excellent preservation of the recovered fossils, it appears likely the Kimmeridgian limestones are going to prove invaluable in increasing knowledge of the insect diversity of the Upper Jurassic, due to the superior quality of fossil preservation in comparison to those from the Bavarian lithographic limestone. This period proved to be an important time for the transition of evolution in terrestrial environments as the diversifying of flowering plants in the Lower Cretaceous period approached.
Source

Nel A, Nel P, Krieg-Jacquier R, Pouillon J, Garrouste R. (2014) Exceptionally preserved insect fossils in the Late Jurassic lagoon of Orbagnoux (Rhône Valley, France) PeerJ 2:e510 http://dx.doi.org/10.7717/peerj.510

That is all for this time I plan to get back into the habit of posting on a weekly basis so keep an eye out for it !
Thanks for reading George.