NEWSLETTER 2/2009 20.Novermber.2009
# Dana Ehret, Florida Museum of Natural History, University of Florida, Gainesville
- 09.11.2009: 38 new data, 126 new analysed papers
- 25.10.2009: 165 new data, 110 new analysed papers
- 10.10.2009: 241 new data, 142 new analysed papers
Sunday, 22. November 2009 (22:00)
New function of the website:
In the list of species now you can find the name of the author of first description and the valid name of species (see "info-box").
EHRET, D.J. & MACFADDEN, B.J. & SALAS-GISMONDI, R. (2009)
Caught in the act: trophic interactions between a 4-million-year-old white shark Carcharodon) and mysticete whale from Peru. Palaios, 24: 329-333 (Keywords: Neogen Pliozän; Südamerika Peru; Carcharodon sp.)
EHRET, D. & HUBBELL, G. & MACFADDEN, B. (2009)
Exceptional preservation of the white shark Carcharodon (Lamniformes, Lamnidae) from the early Pliocene of Peru. Journal of Vertebrate Paleontology, 29 (1): 1-13 (Keywords: Neogen Pliozän; Südamerika Peru; Carcharodon sp., Carcharodon carcharias)
IVANOV, A. & LUCAS, S.G. & KRAINER, K. (2009)
Pennsylvanian fishes from the Sandia Formation, Socorro County, New Mexico. New Mexico Geological Society Guidebook, 60th Field Conference, Geology of the Chupadera Mesa Region: 243-248 (Keywords: Karbon Oberkarbon; Nordamerika New Mexico; Stethacanthus sp., Bythiacanthus sp., Petalodus cf. P. acuminatus, Peripristis cf. P. semicircularis)
LUCAS, S.G. & SPIELMANN, J.A. (2009)
Low diversity selachian assemblage from the upper cretaceous Greenhorn Limestone, Socorro County, New Mexico. New Mexico Geological Society Guidebook, 60th Field Conference, Geology of the Chupadera Mesa Region: 311-314 (Keywords: Kreide Oberkreide; Nordamerika New Mexico;Ptychodus anonymous, Ptychodus whipplei, Ptychodus occidentalis, Squalicorax sp.)
SPIELMANN, J.A. & PENCE, R. & LUCAS, S.G. (2009)
A nearshore vertebrate assemblage from the late cretaceous (Turonian) Atarque Sandstone, Socorro County, New Mexico. New Mexico Geological Society Guidebook, 60th Field Conference, Geology of the Chupadera Mesa Region: 315-320 (Keywords: Kreide Oberkreide; Nordamerika New Mexico; Hybodus sp., Ptychodus cf. P. mammillaris, Ptychodus whipplei, Chlioscyllium greeni, Leptostyrax sp., Scapanorhynchus raphiodon, Cretodus semplicatus, Cretolamna appendiculata, Squalicorax falcatus, Ischyrhiza mira, Ptychotrygon triangularis, Paranomotodon sp., Rhinobatos sp., Pseudohypolophus mcnultyi, Ischyrhiza schneideri Chondrichthyes indet., Odontaspidae indet.)
KRIWET, J. & KIESSLING, W. & KLUG, S. (2009)
Diversification trajectories and evolutionary life-history traits in early sharks and batoids. Proceedings of the Royal Society, Biological Series, 276: 945-951 (Keywords: Jura Unterjura)
KLUG, S. & KRIWET, J. & BÖTTCHER, R. & SCHWEIGERT, G. & DIETL, G. (2009)
Skeletal anatomy of the extinct shark Paraorthacodus jurensis (Chondrichthyes; Palaeospinacidae), with comments on synechodontiform and palaeospinacid monophyly. Zoological Journal of the Linnean Society, 157: 107-134 (Keywords: Jura Oberjura; Europa Deutschland; Paraorthacodus jurensis)
KLUG, S. (2009)
Monophyly, Phylogeny and Systematic Position of the Synechodontiformes (Chondrichthyes, Neoselachii). Zoologica Scripta doi: 10.1111/j.463-6409.2009.00399.x (Keywords: Jura Kreide Paläozän; Paraorthacodus jurensis, Macrourogaleus hassei, Palidiplospinax enniskilleni, Synechodus sp., Sphenodus macer; Paraorthacodontidae; Paraorthacodontidae)
JAMES, K.C. & EBERT, D.A. & LONG, D.J. & DIDIER, D.A. (2009)
A new species of chimaera, Hydrolagus melanophasma sp. nov. (Chondrichthyes: Chimaeriformes: Chimaeridae), from the eastern North Pacific. Zootaxa, 2218: 59-68 (Keywords: rezent; Hydrolagus melanophasma)
JEONG, C.-H. & NAKABO, T. (2009)
Hongeo, a new skate genus (Chondrichthyes: Rajidae), with redescription of the type specie. Ichthyological Research, 56: 140-155; (Keywords: rezent; Hongeo koreana)
Shark Teeth Provide Key To North Sea’s Climatic Past
ScienceDaily (Oct. 20, 2009) — A team of German and British scientists have used fossilised shark teeth to reconstruct the climate of the North Sea during the Palaeogene period, between 40 and 60 million years ago. The results suggest that the North Sea was for a brief period isolated from surrounding oceans, resulting in surface-water freshening and a significant reduction in the diversity of life.
The Palaeogene was a time when greenhouse conditions prevailed and mammals began to diversify in the wake of the mass extinction event that saw the demise of the dinosaurs, along with 65% of all species. It also featured a brief episode of global warming known as the Palaeocene-Eocene thermal maximum (PETM), a rapid climatic disturbance that saw temperatures rise by around six degrees in a 20,000 year period.
Whilst scientists already have a lot of information about the climate on land and in open water during the period, very little has previously been known about the climate of marginal seas like the North Sea. The researchers used oxygen isotope data obtained from shark teeth recovered from the London and Hampshire basins, as well as sites in Denmark, Belgium, the Netherlands and Sweden. They cover a 33 million year period during the Palaeocene-Eocene epochs, representing both shallow and deeper water depths.
Shark teeth are continually shed throughout their lives, so they are relatively abundant in the fossil record. Often they are the only part of a shark to be fossilised, with specimens from as far back as 450 million years ago having been discovered.
When the teeth grow, their oxygen isotope ratio mirrors that of the sea water they are in, so fossilised teeth can be used as a record of palaeo-temperatures. Warmer seas contain more of the heavier isotope, 18O, as it is easier for the lighter 16O to be vaporised. They are also used to indicate the salinity of water, as the water becomes more salty with increased water evaporation.
The results indicate that the North Sea was once far less salty than it is today. For a period of between 2 and 4 million years, the ratio of 18O to 16O was a substantially lower than the average for sea waters of that period, with the value lower even than some contemporary freshwater lakes.
The period of surface water freshening began close to the PETM. At this time, around 55 million years ago, relative sea-level fall, tectonic uplift and volcanic activity meant that the North Sea was temporarily isolated from surrounding oceans. Tectonic uplift raised Western Scotland by around 2-3 km, causing a land bridge to form between the Faeroe-Shetland and Roackall basins.
With circulation between the North Sea and the North Atlantic Ocean restricted, the waters of the North Sea became significantly fresher. This freshening was increased as rivers and precipitation flowed into the isolated North Sea. The result was a significant drop in the diversity of life in the North Sea, with the microorganism foraminifera being particularly affected.
The research is published in the latest issue of the Journal of the Geological Society, which appears online August 24.
Geological Society of London (2009, October 20). Shark Teeth Provide Key To North Sea’s
Tags Reveal White Sharks Have Neighborhoods In The North Pacific
ScienceDaily (Nov. 4, 2009) — The white shark may be the ultimate loner of the ocean, cruising thousands of miles in a solitary trek, but a team of researchers has discovered that the sharks have maintained such a consistent pattern of migration that over tens of thousands of years the white sharks in the northeastern Pacific Ocean have separated themselves into a population genetically distinct from sharks elsewhere in the world.
"White sharks are a large, highly mobile species," said Salvador Jorgensen, a postdoctoral scholar at Stanford's Hopkins Marine Station. "They can go just about anywhere they want in the ocean, so it's really surprising that their migratory behaviors lead to the formation of isolated populations."
Scientists with the Tagging of Pacific Predators (TOPP) program combined satellite tagging, passive acoustic monitoring and genetic tags to study white sharks (Carcharodon carcharias) -- popularly known as great white sharks -- in the North Pacific. The team consisted of researchers from Stanford University, University of California-Davis, Point Reyes Bird Observatory and the Pelagic Shark Research Foundation, and the details of their study are to be published online Nov. 3 by the Proceedings of the Royal Society B.
The fact that the northeastern Pacific white sharks undergo such a consistent, large-scale migration, and that they are all closely related and distinct from other known white shark populations, suggests that it is possible to conduct long-term population assessment and monitoring of these animals.
Barbara Block, professor of marine sciences at Stanford and a coauthor of the paper, said, "Catastrophic loss of large oceanic predators is occurring across many ecosystems. The white sharks' predictable movement patterns in the northeastern Pacific provide us with a super opportunity to establish the census numbers and monitor these unique populations. This can help us ensure their protection for future generations."
The researchers used a combination of satellite and acoustic tags to follow the migrations of 179 individual white sharks between 2000 and 2008. These sharks were adults or sub-adults that ranged in size up to 4,000 pounds, and were individually tagged at sites along the central California coast, including the Gulf of the Farallones, Tomales Bay and Año Nuevo. The electronic tags reveal that the sharks spend the majority of their time in three areas of the Pacific: the North American shelf waters of California; the slope and offshore waters around Hawaii; and an area called the "White Shark Café," located in the open ocean approximately halfway between the Baja Peninsula and the Hawaiian Islands.
"The thing we've learned about white sharks," said Scot Anderson, a marine biologist with the National Park Service, who has been involved in white shark research in Northern California for more than two decades, "is that they're not swimming around aimlessly -- they are very selective predators." Anderson is a coauthor of the paper.
Based on years of data demonstrating that the white sharks were homing with high fidelity back to California, the research team placed acoustic listening receivers on the ocean floor at sites thought to be high residency areas, or "hot spots."
By attaching 78 acoustic tags that create a unique "ping" or acoustic code for each tagged shark, the researchers were able to detect when the white sharks came within 250 meters (820 feet) of a receiver. This allowed the researchers to discern their pattern of coastal movements in high detail. The acoustic-tagged sharks spent time at four key sites along the central and northern California coast, each of which supports large colonies of seals and sea lions: Southeast Farallon Island, Tomales Point, Año Nuevo Island and Point Reyes. The tags revealed that often sharks had favorite sites where they would remain resident for up to 107 days, although they occasionally would make brief visits to the other nearshore hot spots.
"The sharks were detected frequently at their chosen site," Jorgensen said, "which means that they are patrolling around there nearly constantly, for long periods of time. They will occasionally visit one of the adjacent sites, but they always come back."
The team also was surprised to learn about new movements that the acoustic tags revealed in some nearshore locations. They found five white sharks were detected on acoustic receivers beneath the Golden Gate Bridge that originally were installed to listen for salmon, which migrate from the bay to the sea and back again. There are currently no detectors in San Francisco Bay, so there are no data to indicate how far or why the sharks crossed into the bay; however, seals and sea lions are in the region and could be potential prey for the large sharks. Five sharks also were acoustically detected close to shore in Hawaii off Waialua Bay and Kualoa Point on Oahu, and off the coast of Kona.
Genetics techniques were used to examine the relationships of the California sharks to all other white sharks examined globally. Studies of maternally inherited mitochondrial DNA sequences show that the populations are distinct, and suggest that the northeastern Pacific population may have been founded by a relatively small number of sharks in the late Pleistocene -- within the last 200,000 years or so. The other populations of white sharks are concentrated near Australia and South Africa.
Molecular geneticist Carol Reeb, a research associate at Stanford, said, "If you had asked us a few years ago, we would have said white sharks found in California probably migrated throughout the Pacific. Now, even though we know they travel great distances, their paths are surprisingly constrained to specific routes. This explains how a highly migratory marine species becomes a genetically isolated population. This also makes it much easier to appreciate how vulnerable the northeastern Pacific white shark population could become if too many individuals were taken as either catch or bycatch, since these sharks do not appear to interbreed with other shark populations."
Christopher Perle, a Stanford graduate student in biology, is also a coauthor of the paper. Other coauthors are A. Peter Klimley, an adjunct associate professor at UC-Davis; Taylor Chapple, a graduate student at UC-Davis; Sean Van Sommeran, executive director of the Pelagic Shark Research Foundation; Callaghan Fritz-Cope, operations director of the Pelagic Shark Research Foundation; and Adam C. Brown, of the Point Reyes Bird Observatory.