PRESS RELEASE - Teeny Teeth Indicate Ancient Shark Nurseries

September 9, 2011
DEERFIELD, IL (September 9, 2011) – Fuelled by Hollywood and its vision of Jaws, sharks conjure images of fearsome predators patrolling our seas in search of their next unfortunate victim. It is therefore hard to imagine sharks as relatively small, harmless fishes living in lakes and rivers, as many species were more than 200 million years ago. Some scientists have suggested that these ancient sharks bred in the shallows of freshwater lakes, forming nurseries for their hatchlings. Reporting in the most recent issue of the Journal of Vertebrate Paleontology, a team of German paleontologists support this claim with spectacular 230 million-year-old fossil egg capsules and tiny teeth from Kyrgyzstan.



Figure 2
The Madygen Formation in southwestern Kyrgyzstan is well known to paleontologists for its exquisite preservation of insects and plants from the Late Triassic – a time when the earliest dinosaurs walked the earth. “Today, this amazing fossil site is one of the farthest points on land from any sea – quite similar to the situation during the Late Triassic,” said Sebastian Voigt, one of the authors of the study. It was therefore something of a surprise when fossil shark eggs and babies were recently discovered in this area. Lead author of the study, Jan Fischer of the Geologisches Institut, TU Bergakademie Freiberg, remarked that “the chemistry of the tooth enamel indicates that the Madygen nursery was unequivocally created in freshwater, which is in sharp contrast to all modern egg laying sharks, which spawn exclusively in the sea.” 



 Figure 3
The team found the tips of dozens of tiny teeth together with egg capsules representing two different species of shark. One species is based on both teeth and egg capsules and is considered to be member of a family of sharks called hybodontids. The second species is based solely on egg capsules and probably is a type of shark known as a xenacanthid. The hybodontids became extinct at about the same time as the dinosaurs (65 million years ago), while the xenacanthids failed to survive beyond the Triassic, 200 million years ago.



Figure 4
Fossil sharks are generally rather rare. This is partly due to their cartilaginous skeleton, which usually is not preserved as a fossil. Consequently, painstaking searches of large quantities of rock often yield very little reward. As Michael Buchwitz, another author of the report, noted, “The fossil record of sharks is no laughing matter; a spine here, a tooth there, or three miniscule denticles [small spines of the skin] picked from a 10 kilogram sample. Therefore, dozens of egg capsules alongside juvenile teeth in one deposit is a dream come true!"


Almost all of the tiny teeth represent small juveniles. Only a very small number of adult teeth have been discovered. This suggests that just like modern sharks, these freshwater cousins spawned in shallow waters. The young sharks lived in these more protected areas before moving away from the lake shoreline as they matured. However, where the adults went after spawning is another matter. Voigt is “curious to know if the adult sharks permanently lived in nearby freshwaters or perhaps migrated hundreds of kilometers from the sea upstream for the purpose of breeding.” Such a breeding style would make these ancient sharks similar to modern-day salmon, which undertake a similarly long trek for breeding. For the time being that is a question that even the remarkable Madygen deposits cannot answer.


About the Society of Vertebrate Paleontology
Founded in 1940 by thirty-four paleontologists, the Society now has more than 2,300 members representing professionals, students, artists, preparators and others interested in Vertebrate Paleontology. It is organized exclusively for educational and scientific purposes, with the object of advancing the science of vertebrate paleontology.

Journal of Vertebrate Paleontology
The Journal of Vertebrate Paleontology (JVP) is the leading journal of professional vertebrate paleontology and the flagship publication of the Society. It was founded in 1980 by Dr. Jiri Zidek and publishes contributions on all aspects of vertebrate paleontology.

For complimentary access to the full article beginning Sept. 10, 2011, visit

The article appears in the Journal of Vertebrate Paleontology 31(5), published by Taylor and Francis.


Journal website: Society of Vertebrate Paleontology:

Jan Fischer
Geologisches Institut
TU Bergakademie Freiberg
Bernhard-von-Cotta Strasse 2
09599 Freiberg
Tel: +49-176-22306394
Tel: +49-3731-393812

Dr. Sebastian Voigt
Geologisches Institut
TU Bergakademie Freiberg
Bernhard-von-Cotta Strasse 2
09599 Freiberg
Tel: +49-3731-392038

Prof. Joerg W. Schneider
Geologisches Institut
TU Bergakademie Freiberg
Bernhard-von-Cotta Strasse 2
09599 Freiberg
Tel: +49-3731-392856

Michael Buchwitz, MSc
Geologisches Institut
TU Bergakademie Freiberg
Bernhard-von-Cotta Strasse 2
09599 Freiberg
Tel: +49 3731-393499

Silke Voigt 
Goethe Universität Frankfurt am Main
Institut für Geowissenschaften
Altenhöferallee 1
60438 Frankfurt
Tel: +49 69-798-40190

Other Experts Not Associated with this Study

John Long   
900 Exposition Boulevard
Los Angeles, CA 90007
Tel: +1-213-763-3367

Ronald Böttcher  
Stattliches Museum für Naturkunde
Rosenstein 1
70191 Stuttgart
Tel: +49 711-8936-145

Catalina Pimiento  
Biology Graduate Student
Florida Museum of Natural History
University of Florida
and Smithsonian Tropical Research Institute
Center of Paleoecology and Archaeology
Tel: +1-352-273-1931

Andrew B. Heckert  
Department of Geology
Appalachian State University
ASU Box 32067
Boone, NC 28608-2067
Tel: +1-828-262-7609

Gilles Cuny    
The Natural History Museum of Denmark
Oster Voldgade 5-7
1350 Copenhagen K
Tel: +45 3532-2364


Figure 1: Photo of the Madygen area in southwestern Kyrgyzstan, Central Asia (Copyright by Sebastian Voigt).

Figure 2: Fossilized egg capsules (known as Palaeoxyris alterna) of the hybodont shark Lonchidion ferganensis. From left to right: uncompressed preservation, compressed preservation with typical cone-like appearance, and life reconstruction.

Figure 3: Fossilized egg capsules (known as Fayolia sharovi) probably from a xenacanthid shark. From left to right: uncompressed preservation, compressed preservation, and life reconstruction.

Figure 4: A tiny juvenile tooth of Lonchidion ferganensis from the nursery, and a life reconstruction of the 30–40 cm long adult hybodont shark (Life reconstruction copyright by Frederik Spindler).