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April 7, 2011
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Palaeontology  Seminar - Cranial morphology of fossil  hybodont sharks: new information from CT scan studies

Thursday - TODAY - 7th April, Neil Chalmers Seminar Room, DC2,  16:00

Dr.  Jennifer Lane, Bayerische Staatssammlung für Paläontologie und Geologie,  Munich

 

The  growing field of palaeontological CT scanning has only recently begun to be  applied to fossil chondrichthyan fishes (i.e., sharks, rays, and chimaeroids).  In recent years, CT scan-based studies have provided new information on  chondrichthyan cranial morphology, particularly regarding internal features such  as the interior surface of the braincase and the inner ear.

 

Many of these  features have turned out to be significant in shedding new light on patterns of  chondrichthyan evolution. Hybodonts, the sister group of modern sharks, are of  particular interest in what they can reveal about the evolutionary history of  their living relatives.

 

The inner ear of modern sharks (neoselachians) is highly  adapted toward low-frequency semi-directional sound detection (LFSDP). New  investigations of two fossil hybodonts (Tribodus limae and Egertonodus basanus) using  high-resolution CT scanning confirms that the structure of the inner ear in  these sharks was also adapted for LFSDP. However, this adaptation is absent in  earlier chondrichthyans (e.g., symmoriiforms, ctenacanths, Pucapampella), suggesting that it arose  only after the divergence of the hybodont/neoselachian lineage from these  earlier groups. Other features of evolutionary interest include.the loss of the  cranial fissures and elaboration of the vagal and glossopharyngeal nerve canals;  development of a medial capsular wall; and changes in patterns of cranial  arterial circulation.

 

In facilitating identification of key features such as  positions of nerve and blood vessel pathways and foramina, CT scanning and  digital reconstruction techniques may also pave the way for future developmental  studies (such as reconstructing the positions and growth patterns of the  embryonic cranial cartilages).

 

Contact: Greg Edgecombe  g.edgecombe@nhm.ac.uk

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Friday April 8th
Flett Theatre

 

11:30 am - 12:30 pm


Larval morphology  of the forensically important Muscidae of Europe


Andrzej  Grzywacz
Nicolaus Copernicus University, ToruÅ„,  Poland


The Muscidae is a large  dipteran family of some 4500 species and with a cosmopolitan distribution. Many  species exhibit various degrees of synanthropy, and some are important from a  medical and veterinary point of view, like those attracted to decaying organic  matter (e.g. decomposing bodies). Housefly species on decomposed bodies, both as  larvae and adults were found in carrion experiments and death investigations.  Application of methods  of Forensic Entomology requires proper species  identification of collected material.


The morphology of immature stages in  carrion visiting houseflies is unequally studied. In some species immature  stages are not described and in the others only some stages are known. On the  second hand characters used in some keys do not allow to easy species  identification. It results in serious problems with identification of immature  houseflies in forensic cases.


During an ongoing project morphological data  concerning the immature stages of all European species of Muscidae of forensic  importance will be revised. Results will be used to prepare an identification  key for the larvae of forensically important species. For this purpose results  obtained during this visit in Natural History Museum will be essential, as also  for the future research projects concerned on larval morphology of Muscidae and  Fanniidae.

 


Contact: Vladimir Blagoderov - vlab@nhm.ac.uk