NEWSLETTER 12/2013 17.12.2013

Please acknowledge use of the database www.shark-references.com in your publications, and cite: 

Pollerspöck, J. 2013, Bibliography database of living/fossil sharks, rays and chimaeras (Chondrichtyes: Elasmobranchii, Holocephali), www.shark-references.com, World Wide Web electronic publication, Version 2013

I wish you and your family marry Christmas and a happy new year!


¡Feliz Navidad y próspero año nuevo!
Buon Natale e felice anno nuovo!

Feliz Natal e próspero ano novo

Frohe Weihnachen und ein glücklichen neues Jahr!

Joyeux Noël et bonne année!
Glædelig jul og godt nytår!



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New images at shark-references:

Many thanks to the following persons for the permission to use their images:
Please support shark-references and send your images to: info@shark-references.com

Missing papers:

Many thanks to all friends of shark-references, who send me some missing papers last month!

Shark-References would kindly like to ask you for your contribution to this project.

Please support www.shark-references.com and send missing papers (not listed papers or papers without the infosymbol) to juergen.pollerspoeck@shark-references.com.




Northeast Pacific Shark Symposium

Saturday, March 22, 2014 8am-5pm

Join us for a series of 5–15-minute “lightning talks” on current Northeast Pacific shark research.

Event background:

Since 2004 the Seattle Aquarium has hosted biennial cowshark conservation workshops to gather shark biologists to share knowledge about these little-known species. Over the years the meeting has increased in size and scope. In December of 2011 the first Pacific Shark Workshop was held in Vancouver, B.C. Because of the success of this meeting and the growth of the cowshark meeting, the Aquarium, in collaboration with the Pacific Shark Research Center at Moss Landing Marine Labs, California and the IUCN Shark Specialist Group Northeast Regional working group, is launching the Northeast Pacific Shark Symposium.

Reservation cost is $40 per person. Click here to register.


The KwaZulu-Natal Sharks Board is pleased to confirm that the second Sharks International symposium will be held in Durban, South Africa on 2-6 June 2014. This is a sequel to the highly successful inaugural Sharks International meeting in Cairns, Australia in June 2010. The meeting will comprise four full days of presentations, commencing Monday 2 June and ending Friday 6 June, with Wednesday 4 June set aside for a variety of exciting mid-conference excursions.
The aim of this conference is to provide a forum for the world’s leading shark and ray researchers, along with students and early career scientists to meet, share ideas, update information and report on the progress of their most recent scientific studies. We would encourage any researchers and students with a general interest in the marine environment to also attend as networking opportunities at a conference of this nature and size are enormous.
For further information please visit the Symposium’s web page at:
Any queries regarding the symposium can also be sent to the organising committee at:

News from shark-references:

in preparation (spring 2014):

Papers of the year 2013


Host - Parasites List and with new (!) Parasite - Hosts List Version 2

Please send missing/not used papers to juergen.pollerspoeck@shark-references.com

New book:

Deep–sea Cartilaginous Fishes of the Indian Ocean. Volume 1. Sharks
D.A. Ebert, 2013.

Deep–sea Cartilaginous Fishes of the Indian Ocean. Volume 1. Sharks
This volume is a comprehensive, fully illustrated Catalogue of the Deep–sea Sharks of the Indian Ocean, encompassing FAO Fishing Areas 51 and 57, and that portion of Area 47 off South Africa from about 18°42’E to 30°00’E. The present volume includes 8 orders, 23 families, 46 genera, and 117 species of shark–like fishes occurring in the Indian Ocean deep–sea.

free download: http://www.fao.org/docrep/019/i3477e/i3477e.pdf

This volume is a comprehensive, fully illustrated Catalogue of the Deep–sea Sharks of the Indian Ocean, encompassing FAO Fishing Areas 51 and 57, and that portion of Area 47 off South Africa from about 18°42’E to 30°00’E. The present volume includes 8 orders, 23 families, 46 genera, and 117 species of shark–like fishes occurring in the Indian Ocean deep–sea. It provides accounts for all orders, families, and genera and all keys to taxa are fully illustrated. A species representative account of each genus is also provided and includes: valid modern names and original citation of the species; synonyms; the English, French, and Spanish FAO names for the species; a lateral view and often other useful illustrations; field marks; diagnostic features; distribution, including a GIS map; habitat; biology; size; interest to fisheries and human impact; local names when available; a remarks sections; and literature. The volume is fully indexed and also includes sections on terminology and measurements for sharks including an extensive glossary, and a dedicated bibliography.

New described species/Taxonomic News:


CAIRA, J.N. & RODRIGUEZ, N. & PICKERING, M. (2013) New African species of Echinobothrium (Cestoda: Diphyllidea) and implications for the identities of their skate hosts. Journal of Parasitology, 99 (5): 781-788

New species: Echinobothrium mercedesae, Echinobothrium yiae

Abstract: Two new species of diphyllidean cestodes of the genus Echinobothrium, each hosted by a different skate species in the Raja miraletus complex, are described. Echinobothrium mercedesae n. sp. is described from R. cf. miraletus 2 off Senegal. Echinobothrium yiae n. sp. is described from R. cf. miraletus 1 off South Africa. Both species are small worms that differ from their 29 described congeners in the combination of number of cephalic peduncle spines per column, hook formula, number and arrangement of testes, and arrangement of vitelline follicles. They are easily distinguished from one another in that whereas the vitelline follicles of E. yiae n. sp. are circumcortical, they are lateral in E. mercedesae n. sp., and also in number of cephalic peduncle spines per column (14-17 vs. 10-12). Echinobothrium yiae n. sp. is also unusual in that the cephalic peduncle spines stop short of the anterior margin of the peduncle. In addition, although the paucity of available material precluded their formal description, evidence of 2 additional new species parasitizing R. miraletus also from Senegal is presented. In combination these worms provide support for the interpretation that what is currently recognized as Raja miraletus actually consists of a complex of geographically restricted species, rather than a polymorphic species of multiple parapatric or allopatrically distributed populations. This interpretation is not only supported by previously published molecular data, but also by newly collected morphological data involving differences in the color patterns of disc ocelli among host specimens of the 3 forms available as a result of digital efforts to ensure the accuracy of host identifications, which are also presented here.



BATCHELOR, T.J. (2013) A new species of Vectiselachos (Chondrichthyes, Selachii) from the Early Cretaceous of southern England. Proceedings of the Geologists' Association, 124 (6): 967–972

New species: Vectiselachos gosslingi

Abstract: Teeth of a new species of hybodont shark Vectiselachos (Chondrichthyes: Lonchidiidae) are described from the late Aptian (Early Cretaceous) of southern England. Vectiselachos gosslingi sp. nov. has very distinctive coarse striations that form raised ridges over the occlusal surfaces of the crown.

IVANOV, A.O. (2013) Chondrichthyans from the early/late Carboniferous boundary beds of the Gissar Mountains, Uzbekistan. New Mexico Museum of Natural History and Science, Bulletin, 60: 143-151

New species: Gissarodus flabellatus
New genus: Gissarodus 

Abstract: Chondrichthyan microremains are described from the Late Serpukhovian-Early Bashkirian of the Aksu sections, Surkhantau Range, southwestern Gissar Mountains, Uzbekistan. The fauna contains an assemblage including diverse symmoriiforms, Denaea cf. D. williamsi Ginter and Hansen, Denaea sp., Stethacanthulus decorus (Ivanov), S. meccaensis (Williams), a euselachian, Gissarodus flabellatus gen. et sp. nov, and various chondrichthyan denticles and scales.

New Paper


Recent Papers:

ALATORRE-RAMIREZ, V.G. & GALVAN-MAGAÑA, F. & TORRES-ROJAS, Y.E. (2013) Trophic habitat of the Pacific sharpnose shark, Rhizoprionodon longurio, in the Mexican Pacific. Journal of the Marine Biological Association of the United Kingdom, 93 (8): 2217-2224  http://dx.doi.org/10.1017/S0025315413000957
AWRUCH, C.A. (2013) Reproductive endocrinology in chondrichthyans: The present and the future. General and Comparative Endocrinology, 192: 60-70 http://dx.doi.org/10.1016/j.ygcen.2013.05.021
BARNETT, A. & YICK, J.L. & ABRANTES, K.G. & AWRUCH, C.A. (2013) Trophic ecology of an abundant predator and its relationship with fisheries. Marine Ecology Progress Series, 494: 241-248  http://dx.doi.org/10.3354/meps10577
BLACK, M.P. & GROBER, M. & SCHREIBER, C. & COCO, C. & DOVE, A. (2013)Whale shark (Rhincodon typus) behavior: A multi-year analysis of individuals at Georgia Aquarium. Abstract. PeerJ PrePrints, 1: e88v1 http://dx.doi.org/10.7287/peerj.preprints.88v1
BLUEMEL, J.K. & FRENCH, G.C. & ROWAT, D. (2013) An aerial view: Insights into the effects of ecotourism on the behavior of whale sharks (Rhincodon typus) in Seychelles. Abstract. PeerJ PrePrints, 1:e103v1 http://dx.doi.org/10.7287/peerj.preprints.103v1
CERUTTI-PEREYRA, F. & THUMS, M. & AUSTIN, C.M. & BRADSHAW, C.J.A. & STEVENS, J.D. & BABCOCK, R.C. & PILLANS, R.D. & MEEKAN, M.G. (2013)Restricted movements of juvenile rays in the lagoon of Ningaloo Reef, Western Australia – evidence for the existence of a nursery. Environmental Biology of Fishes, in press  http://dx.doi.org/10.1007/s10641-013-0158-y
COUTURIER, L.I.E. & ROHNER, C.A. & RICHARDSON, A.J. & MARSHALL, A.D. & JAINE, F.R.A. & BENNETT, M.B. & TOWNSEND, K.A. & WEEKS, S.J. & NICHOLS, P.D. (2013) Stable Isotope and Signature Fatty Acid Analyses Suggest Reef Manta Rays Feed on Demersal Zooplankton. PLoS ONE, 8 (10): e77152 http://dx.doi.org/10.1371/journal.pone.0077152
DALE, J.J. & DRAZEN, J.C. & HOLLAND, K.N. (2013) Stingray life history trade-offs associated with nursery habitat use inferred from a bioenergetics model. Marine Biology, 160 (12): 3181-3192  http://dx.doi.org/10.1007/s00227-013-2305-6
DE LA PARRA, R. & DOVE, A.D. & GALVÁN, B. (2013) Whale shark behaviors observed in northeastern Quintana Roo, Mexico. Abstract. PeerJ PrePrints, 1:e132v1 http://dx.doi.org/10.7287/peerj.preprints.132v1
EBERT, D.A. (2013) Deep-sea Cartilaginous Fishes of the Indian Ocean. Volume 1. Sharks FAO Species Catalogue for Fishery Purposes. No. 8, Vol. 1. Rome, FAO. 256 pp.
ECHWIKHI, K. & SAIDI, B. & BRADAI, M.N. (2013) Elasmobranchs longline fisheries in the Gulf of Gabès (southern Tunisia). Journal of the Marine Biological Association of the United Kingdom, in press  http://dx.doi.org/10.1017/S0025315413000726
EKSTROM, L.J. & KAJIURA, S.M. (2013) Pelvic girdle shape predicts locomotion and phylogeny in batoids. Journal of Morphology, in press http://dx.doi.org/10.1002/jmor.20201
FARRELL, E.D. & O'SULLIVAN, N. & SACCHI, C. & MARIANI, S. (2013) Multiple paternity in the starry smooth-hound shark Mustelus asterias (Carcharhiniformes: Triakidae). Biological Journal of the Linnean Society, in press http://dx.doi.org/10.1111/bij.12179
FRENCH, G.C. & BLUEMEL, J.K. & ROWAT, D. (2013) Developing appropriate conservation measures for the seasonal whale shark feeding aggregation in Seychelles using ecological modeling tools. Abstract. PeerJ PrePrints, 1:e125v1 http://dx.doi.org/10.7287/peerj.preprints.125v1
GALVAN, B.E. & FOX, S. & DE LA PARRA, R. (2013) Whale shark regional research collaboration between Utila, Honduras and Isla Mujeres, México. Abstract. PeerJ PrePrints, 1:e133v1  http://dx.doi.org/10.7287/peerj.preprints.133v1
GUIDA, L. & WALKER, T.I. & REINA, R.D. (2013) First record of a bicephalic chondrichthyan found in Australian waters; the southern fiddler ray, Trygonorrhina dumerilii (Chondrichthyes: Rhinobatidae). Marine and Freshwater Research, in press http://dx.doi.org/10.1071/MF13198
HAMMERSCHLAG, N. & GALLAGHER, A.J. & CARLSON, J.K. (2013) A revised estimate of daily ration in the tiger shark with implication for assessing ecosystem impacts of apex predators. Functional Ecology, 27 (5): 1273-1274 http://dx.doi.org/10.1111/1365-2435.12157
KADRI, H. & MAROUANI, S. & SAÏDI, B. & BRADAI, M.N. & BOUAÏN, A. & MORIZE, E. (2014) Age, growth, sexual maturity and reproduction of the thornback ray, Raja clavata (L.), of the Gulf of Gabès (south-central Mediterranean Sea). Marine Biology Research, 10 (4): 416-425  http://dx.doi.org/10.1080/17451000.2013.797584
KILADZE, A.B. & CHERNOVA, O.F. (2013) Biology of the brownbanded bamboo shark Chiloscyllium punctatum Muller et Henle, 1838: mode of the species.РЫБОВОДСТВО И РЫБНОЕ ХОЗЯЙСТВО, 1: 49-52
LIU, S.-Y.V. & CHAN, C.-L.C. & LIN, O. & HU, C.-S. & CHEN, C.A. (2013) DNA Barcoding of Shark Meats Identify Species Composition and CITES-Listed Species from the Markets in Taiwan. PLoS ONE, 8 (11): e79373 http://dx.doi.org/10.1371/journal.pone.0079373
LYONS, K. & LOWE, C.G. (2013) Mechanisms of maternal transfer of organochlorine contaminants and mercury in the common thresher shark (Alopias vulpinus). Canadian Journal of Fisheries and Aquatic Sciences, 70 (12): 1667-1672 http://dx.doi.org/10.1139/cjfas-2013-0222
MCKINNEY, J. & HOFFMAYER, E.R. & HOLMBERG, J. & GRAHAM, R. & DE LA PARRA, R. & GALVAN PASTORIZA, B. & FOX, S. & PIERCE, S. & DOVE, A.D.M. (2013) Regional connectivity of whale sharks demonstrated using photo-identification – Western Atlantic, 1999 - 2013. Abstract. PeerJ PrePrints, 1: e98v1 http://dx.doi.org/10.7287/peerj.preprints.98v1
MCKINNEY, J.A. & HOFFMAYER, E.R. & FRANKS, J.S. & HENDON, J.M. & DRIGGERS, W.B. (2013) Seasonal habitat use of whale sharks in the northern Gulf of Mexico, USA 2003 - 2013. Abstract. PeerJ PrePrints, 1: e93v1 http://dx.doi.org/10.7287/peerj.preprints.93v1
MOORE, A.B.M. (2013) Shark nursery identification on a shoestring without getting wet: evidence for the regional importance of the threatened Tigris-Euphrates system to bull sharks. Abstract. In: Progrtamm and Abstracts, 17. European Elasmobranch Association Conference (EEA), Plymouth
NIELSEN, J. & HEDEHOLM, R.B. & SIMON, M. & STEFFENSEN, J.F. (2013)Distribution and feeding ecology of the Greenland shark (Somniosus microcephalus) in Greenland waters. Polar Biology, in press  http://dx.doi.org/10.1007/s00300-013-1408-3
OLIN, J.A. & BEAUDRY, M. & FISK, A.T. & PATERSON, G. (2014) Age-related Polychlorinated Biphenyl Dynamics in Immature Bull Sharks (Carcharhinus leucas).Environmental Toxicology and Chemistry, 33 (1): in press http://dx.doi.org/10.1002/etc.2402
OLIN, J.A. & HUSSEY, N.E. & GRGICAK-MANNION, A. & FRITTS, M.W. & WINTNER, S.P. & FISK, A.T. (2013) Variable delta N-15 Diet-Tissue Discrimination Factors among Sharks: Implications for Trophic Position, Diet and Food Web Models.PLoS ONE, 8 (10): e77567  http://dx.doi.org/10.1371/journal.pone.0077567
PASSEROTTI, M. & ANDREWS, A. & CARLSON, J. & WINTNER, S. & GOLDMAN, K. & NATANSON, L. (2013) Maximum age and missing time in the vertebrae of sand tiger shark (Carcharias taurus): validated lifespan from bomb radiocarbon dating in the western North Atlantic and southwestern Indian Oceans. Marine & Freshwater Research, in press
PAVAN-KUMAR, A. & GIREESH-BABU, P. & SURESH BABU, P.P. & JAISWAR, A.K. & HARI KRISHNA, V. & PANI PRASASD, K. & APARNA CHAUDHARI & RAJE, S.G. & CHAKRABORTY, S.K. & GOPAL KRISHNA & LAKRA, W.S. (2013) Molecular phylogeny of elasmobranchs inferred from mitochondrial and nuclear markers.Molecular Biology Reports, in press  http://dx.doi.org/10.1007/s11033-013-2879-6
RITTER, E.K. & AMIN, R. (2013) Are Caribbean reef sharks, Carcharhinus perezi, able to perceive human body orientation? Animal Cognition, in press http://dx.doi.org/10.1007/s10071-013-0706-z
ROBBINS, R. & BRUCE, B. & FOX, A. (2013) First reports of proliferative lesions in the great white shark, Carcharodon carcharias L., and bronze whaler shark, Carcharhinus brachyurus Günther. Journal of Fish Diseases, in press http://dx.doi.org/10.1111/jfd.12203
ROHNER, C.A. & COUTURIER, L.I.E. & RICHARDSON, A.J. & PIERCE, S.J. & PREBBLE, C.E.M. & GIBBONS, M.J. & NICHOLS, P.D. (2013) Diet of whale sharks Rhincodon typus inferred from stomach content and signature fatty acid analyses.Marine Ecology Progress Series, 493:219-235  http://dx.doi.org/10.3354/meps10500
SMITH, W.D. & MILLER, J.A. & HEPPELL, S.S. (2013) Elemental Markers in Elasmobranchs: Effects of Environmental History and Growth on Vertebral Chemistry.PLoS ONE, 8 (10): e62423  http://dx.doi.org/10.1371/journal.pone.0062423
TORRES-ROJAS, Y.E. & OSUNA, F.P. & HERNÁNDEZ-HERRERA, A. & GALVÁN-MAGAÑA, F. & GARCIA, S.A. & VILLALOBOS-ORTIZ, H. & SAMPSON, L. (2013)Feeding grounds of juvenile scalloped hammerhead sharks (Sphyrna lewini) in the south-eastern Gulf of California. Hydrobiologia, in press http://dx.doi.org/10.1007/s10750-013-1753-9
WERRY, J.M. & CLUA, E. (2013) Sex-based spatial segregation of adult bull sharks, Carcharhinus leucas, in the New Caledonian great lagoon. Aquatic Living Resources, in press  http://dx.doi.org/10.1051/alr/2013063
WHEELER, S. & ROBBINS, W.D. & MCILLWAIN, J. (2013) Reef sharks clean up with a novel inshore mutualistic interaction. Coral Reefs, 32 (4): 1089 http://dx.doi.org/10.1007/s00338-013-1068-3



CAIRA, J.N. & RODRIGUEZ, N. & PICKERING, M. (2013) New African species of Echinobothrium (Cestoda: Diphyllidea) and implications for the identities of their skate hosts. Journal of Parasitology, 99 (5): 781-788  http://dx.doi.org/10.1645/13-198.1
PURIVIROJKUL, W. (2013) Cestodes of the brown-banded bamboo shark Chiloscyllium punctatum (Elasmobranchii: Hemiscylliidae) from the Gulf of Thailand.Walailak Journal of Science and Technology, 10 (6): 591-596



BATCHELOR, T.J. (2013) A new species of Vectiselachos (Chondrichthyes, Selachii) from the Early Cretaceous of southern England. Proceedings of the Geologists' Association, 124 (6): 967–972
GUINOT, G. (2013) Late Cretaceous elasmobranch palaeoecology in NW Europe.Palaeogeography, Palaeoclimatology, Palaeoecology, 388: 23–41 http://dx.doi.org/10.1016/j.palaeo.2013.07.027
IVANOV, A.O. (2013) Chondrichthyans from the early/late Carboniferous boundary beds of the Gissar Mountains, Uzbekistan. New Mexico Museum of Natural History and Science, Bulletin, 60: 143-151
IVANOV, A.O. (2013) New findings of the Early Permian shark endoskeleton. In: Palaeontological and geological monuments and collections: significance of museums for their study and preservation: Collection of scientific articles
IVANOV, A.O. & NESTELL, G.P. & NESTELL, M.K. (2013) Fish assemblage from the Capitanian (Middle Permian) of the Apache Mountains, West Texas, USA. New Mexico Museum of Natural History and Science, Bulletin, 60: 152-160


Researching manta ray brains: Csilla Ari at TEDxTampaBay

Dr. Csilla Ari is a researcher at the University of South Florida College of Medicine, Molecular Pharmacology & Physiology. Csilla found some unique features of manta ray brains which inspired her to start experiments on their cognitive abilities, with a grant from the Save Our Seas Foundation. During these experiments she had some accidental discoveries that might change manta ray research worldwide. She will also talk about new approaches for manta ray conservation. In addition to being a principal investigator for the Foundation for Oceans of the Future and the Director of the Manta Pacific Research Foundation, Dr. Ari's research has been featured in the National Geographic Magazine (Hungary)

Link to the video: http://www.youtube.com/watch?v=SCfsweIsqdA&list=PLsRNoUx8w3rOZIU1x1qyIXKA_eHcvVkMR

source: http://www.isciencetimes.com/articles/4765/20130325/2-headed-shark-fetus-caught-florida-keys.htm?utm_source=twitterfeed&utm_medium=twitter


2-Headed Shark Fetus Caught Off Florida Keys: See Photos Of First Two-Headed Bull Shark Ever Recorded

By Staff Reporter on March 25, 2013 5:52 PM EDT



2-headed bull shark fetus (Photo: Journal of Fish Biology)
2-headed bull shark fetus (Photo: Journal of Fish Biology)

A rare 2-headed shark fetus was discovered by a fisherman just off the Florida Keys coast. According to reports, the fisherman caught a bull shark and discovered the shark possessed a live fetus with two heads!

According to scientists, the odd 2-headed specimen would not have lived very long in the wild. Michigan State University researcher Michael Wagner shared his thoughts on the creature:

"When you're a predator that needs to move fast to catch other fast-moving fish... that'd be nearly impossible with this mutation."

The fisherman shared his rare discovery with scientists. On March 25, the research team finally published the study online via the Journal of Fish Biology. According to records, only six 2-headed sharks have ever been studied. In fact, the latest specimen is the first bull shark with the bizarre characteristic.

The 2-headed deformity is technically known as "axial bifurcation." Scientists explain that the deformity occurs when the embryo fails to split two separate organisms, or twins, completely. This is a very rare mutation that occurs in a number of animals, including humans. "Halfway through the process of forming twins, the embryo stops dividing," Wagner explains.

Michael Wagner and his team of researchers hope the information learned from the deformed shark can allow scientists to one day better understand deformities that arise in sharks.

2-headed bull shark fetus (Photo: Journal of Fish Biology)
2-headed bull shark fetus (Photo: Journal of Fish Biology)
2-headed bull shark fetus (Photo: Journal of Fish Biology)
2-headed bull shark fetus (Photo: Journal of Fish Biology)

source: http://blog.luminescentlabs.org/post/44894948334/chain-catshark-you-dont-have-to-get-out-of-the

Chain catshark! 

You don’t have to get out of the water—these sharks (Scyliorhinus retifer) are very small. The catshark was first witnessed to be fluorescent during an August 2005 research cruise in the Gulf of Mexico, but no photos were taken. This is one of the first images to capture this shark’s biofluorescence! Captured by David Gruber, Vincent Pieribone and John Sparks.

source: http://ocean.si.edu/ocean-news/great-white-shark-evolution#.Uq1bPgpzza4.facebook

Shark Teeth Tell Great White Shark Evolution Story

Credit: Jeff Gage/Florida Museum of Natural History


For the last 150 years, paleontologists have debated the origins of the great white shark. Many believe that they descended from the 50-foot megalodon, also known as the megatooth shark (Carcharocles megalodon), which is often imagined to be a vastly inflated great white. But after the discovery of a new fossil species, announced in November 2012, the consensus seems to be shifting. Instead, great white sharks may be more closely related to mako sharks.

The presumed close relation between the megalodon and great white is based on similarities in tooth structure, as both have saw-like edges on their teeth. This may seem like flimsy evidence for such a grand association, but the only evidence that the megalodon lived at all is their enormous teeth, as a cartilage skeleton has never been found.

The new shark fossil (Carcharodon hubbelli), however, is far more complete: it includes several vertebrae and a full jaw with teeth intact. These teeth, like those of the great white and megalodon, are saw-like—but they aren’t as sharp. Instead, they appear to be something in-between the teeth of the mako shark ancestor (Carcharodon hastalis), which are smooth for efficient fish-eating, and the sharp and jagged seal-munching teeth of the great white shark. The hybrid teeth of this new shark fossil provides evidence that this species is the great white shark ancestor, not the megalodon.

In addition, the new fossil shark lived 6.5 million years ago, placing it at a good time to be an intermediate species between the mako shark ancestor and the great white. This combination of evidence supports the hypothesis that great white sharks are a mammal-eating variation on the mako shark, instead of a shrunken-down version of the megalodon.

Reference: DJ Ehret et al. 2012. Origin of the white shark Carcharodon (Lamniformes: Lamnidae) based on recalibration of the Upper Neogene Pisco Formation of Peru. Palaeontology 55 (6): 1139–1153.


source: http://www.latimes.com/science/sciencenow/la-sci-sn-lemon-sharks-return-to-place-of-birth-20131205,0,7264761.story#ixzz2nehJTD3X


17-year study shows sharks return to give birth where their moms did

There’s no place like home – especially for lemon sharks about to give birth.

Despite absences as long as 17 years, the pregnant sharks returned to the exact spot in the Bahamas where they were born when they were ready to become mothers, according to scientists who have been tracking the creatures since Bill Clinton was in the White House.

Researchers have long suspected that sharks returned to their birthplaces to give birth themselves – a phenomenon known as natal philopatry. Salmon do it. Species that take longer to mature, such as sea turtles, return to the general area of their birthplaces but may be off by hundreds or thousands of kilometers. (Researchers think this may be because animals use the geomagnetic field to home to their birthplace, and that field can change over many years.)

Sharks are considered late-maturing animals, but there have been signs that they practice natal philopatry. For instance, researchers have noticed that sister blacktip reef sharks use the same nursery sites in French Polynesia. Also, analysis of mitochondrial DNA – which is passed directly from mothers to their children – has shown that sharks in different families give birth in different places.

PHOTOS: Tracking lemon sharks for nearly 20 years

But for hard proof, scientists would have to track an individual shark from birth to motherhood. That would be a huge undertaking, but a group of researchers from the U.S., Canada, the Bahamas and Saudi Arabia rose to the challenge. Their initial findings were published online Thursday in the journal Molecular Ecology.

The international team focused on lemon sharks in the Bimini islands of the Bahamas because they are known to spend their first three years in very confined nursery areas before gradually swimming further and further away. Tagged females have been observed giving birth in the same place multiple times, though the birthplaces of those mothers wasn’t known.

So the scientists began tagging baby and toddler lemon sharks in 1995, including a few that were 1 or 2 years old at the time. Each shark was fitted with a transponder, and a tissue sample was removed from a fin for genetic analysis. The researchers returned to the same site for the next 17 years to tag sharks in subsequent birth cohorts. (You can see photos of their work here.)

By 2008, the scientists figured the oldest sharks in their study would be ready to give birth, and they kept their eyes peeled for pregnant sharks returning to the nursery. They used nets and ropes to capture these mothers-to-be and took DNA samples to see whether they were study participants. (Some sharks still had their transponders, but others had lost them over the years.)

After much effort, the researchers captured two sharks. One of them had been enrolled in the study in 1995, when she was estimated to be 2 years old. A few months later, they captured a baby shark that DNA showed to be her offspring. The baby was captured less than 2.5 miles from where the mother had been tagged 13 years earlier.

Study lead author Kevin Feldheim of the Field Museum of Natural History in Chicago said he was “excited and anxious” when the team set out to make their first catches.

“We knew that starting in '08/'09 we should start seeing some females return (if in fact we were correct about our hunch that this was a relatively common phenomenon),” he said in an email. “When we realized we found the first female come back to give birth, we were all relieved.”

The second shark still had the transponder she got in 1997, when she was a newborn. The scientists didn’t find any offspring of hers in 2008, but four of her children were identified in 2012.

Capturing pregnant sharks turned out to be “extremely labor intensive,” so after that first year they simplified things by checking the DNA of baby sharks to see whether their mothers had been tagged in the early days of the study. This method turned up four more cases of mothers returning to their former nursery to give birth.

PHOTOS: Weird sea creatures

In 2012, the most recent year included in the study, the team counted 15 mother sharks using the Bimini nursery. Nine had used the nursery before and were judged to be too old to have been tagged in the study’s early days. Among the six first-time mothers, three had been tagged as babies.

That would seem to nail things down, but the researchers added one more observation. Over the entire course of the study, 59 sharks gave birth in the waters off North Bimini island and six gave birth off South Bimini island – but none of the sharks used both. “Without exception, females were very faithful to one nursery site or the other,” they wrote (italics are theirs).

The evidence led the researchers to conclude that at least some female lemon sharks practice natal philopatry in the Bahamas. And that has “important implications for long-term sustainability of local nursery areas,” they wrote. “It is becoming increasingly clear that these imperiled predators have a complex population structure, and some species can benefit from investments in local conservation measures nested within broader international efforts.”

Feldheim said he felt "very fortunate" to have been part of such a long-term research project, which involved hundreds of student volunteers over the years.

"A study like this comes around once in a great while," he said. "As long as we can continue funding the field and lab work, I hope to keep going for another 20 years."

In addition to Feldheim, the research team included members from the Rosenstiel School of Marine and Atmospheric Science in Miami, the King Abdullah University of Science and Technology in Saudi Arabia, the Great Lakes Institute for Environmental Research in Windsor, Ontario, McGill University in Montreal, Stony Brook University in New York and theUniversity of Illinois at Chicago.