Ontogenetic progression of tesserate chondrification and mineralization in chondrichthyans

Project Leads:

Cyrena Riley (Université du Québec à Rimouski) - Principal Investigator

Richard Cloutier (Université du Québec à Rimouski)

Eileen Grogan (St-Joseph’s University)

Project Status:

In Progress

Type of Initiative:

Ph. D. Research Project

Project Location:

Université du Québec à Rimouski

For which Shark Species:

Thorny skate (Amblyraja radiata), St-Lawrence river

Smooth skate (Malacoraja senta), St-Lawrence river

Black dogfish (Centroscyllium fabricii), St-Lawrence river

Elephant shark (Callorhinchus milii), New Zealand

Project Description:

Conservational efforts towards chondrichthyan populations usually focus on adults; however, early life stages are also susceptible to be influenced by internal and external environmental factors, and thus must also be considered. It is important to thoroughly understand their development in order to identify developmental changes taking place during their ontogeny which may have a potential impact on their survival. An example of a process taking place during larval and juvenile development is the initiation of tesserate mineralization, consisting of small calcified tiles forming on the surface of cartilaginous endoskeletal elements to stiffen them, and which is linked to activities such as feeding and locomotion. A better understanding of the developmental pattern of mineralization in species from all three different groups (sharks, batoids and chimaerids) could also clarify their evolutionary history. Therefore the aim of this research is to describe the progression of endoskeletal chondrification and mineralization in chondrichthyans. Specimens are double cleared and stained to observe the endoskeletal condition. Preliminary results from skates and the chimaera show that anatomical systems (e.g. fins, cranium, vertebral column) and their constituants mineralize following a specific order. Furthermore, each constituant mineralization follows a specific direction, and can partially or completely cover the element (catenated, crustal).

Previous Work:

Riley, C., Cloutier, R. and E. Grogan. 2011. Ontogenetic pattern of mineralization in the thorny skate (Amblyraja radiata). Oral presentation at the American Elasmobranch Society meeting, Minneapolis, Minnesota, USA.

Riley, C., Grogan, E. and R. Cloutier. 2011. Endoskeletal development in extant and extinct chimaerids (Chondrichthyes). Oral presentation at the Early Vertebrate Symposium, Dallas, Texas, USA.

Riley, C., Parent, S. and N. Le François. 2009. Captive Breeding of the Barndoor Skate (Dipturus laevis) and Work on Early-Life Stages. Poster presentation at the American Elasmobranch Society meeting, Portland, Oregon, USA.

Contact Information:

Cyrena Riley <«^–^–<
Ph. D. candidate
Chaire de Recherche en Paléontologie et Biologie Évolutive,
Université du Québec à Rimouski (UQAR),
Office: (418) 723-1986 ext.1724
Laboratory: (418) 723-1986 ext.1438

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