A Tribute to Prof.Farish Jenkins

Farish Jenkins, who has died aged 72, was a showman professor at Harvard whose teaching technique owed as much to Hollywood as to the halls of academe.
Photo: Boston Globe

Photo: Boston Globe

Although his disciplines were biology and zoology, Jenkins was never constrained by rigid scholastic boundaries and considered himself something of a hybrid. He made his name as a vertebrate paleontologist, combining field work in fossils with laboratory research on living creatures to help us understand how the earliest animals lived and moved. He made important discoveries about bird flight and respiratory physiology, as well as elucidating the evolutionary transition from reptiles to mammals .

His lectures had the feel of a performance, not least on account of his old-world charm and gentlemanly air. Particularly memorable were his celebrated “Moby Dick” anatomy lectures, in which Jenkins, strapping on a peg leg, would demonstrate the elements of human locomotion by declaiming passages from Melville’s novel while stumping around like Captain Ahab on the deck of the Pequod. His observations on gait showed students that a peg leg has no arch tendon to absorb shock.

Jenkins was also a talented artist, and would spend hours producing variously hued anatomical drawings on the blackboard for the next day’s lecture, even using a pencil sharpener on his chalk to execute the finer points of detail. Often he would make chalk marks on his dark bespoke suit to illustrate the bones of the body.

Away from the classroom, Jenkins’s work in the field took him to East Africa (where he was once charged by a black rhino), Greenland, Canada and the American West, often in extreme conditions. In the Canadian Arctic, he and his colleagues discovered Tiktaalik roseae, the 375-million-year-old fossil of a fishlike creature which they were sure represented the missing link between fish and four-legged animals on land.

Another major find was what Jenkins called the “ugliest animal in the world”, a 210-million-year-old armoured marine creature which opened its mouth by raising its upper jaw.

For these trips Jenkins would exchange his crisp, tailored shirt and immaculately knotted tie for a rabbit-fur hat, pocket-watch, flask of vodka and a high-powered rifle, an eccentric jumble of kit that caused his students to cast him as a real-life Indiana Jones. “In fact,” noted a colleague, “someone out in Montana who met him for the first time would have thought he was a cowboy or rancher rather than a Harvard professor.”

The eldest of three sons of a marketing executive, Farish Alston Jenkins Jr was born on May 19 1940 in New York City and grew up with his grandmother in Colorado while his father served in the Second World War.

After attending the Taft School at Watertown, Connecticut, Jenkins studied Geology at Princeton University, and from 1961 served nearly four years in the US Marine Corps, including spells in Japan and the Philippines, an experience that taught him to swear “without repeating myself” . After graduating from Yale, he worked at Columbia University before moving to Harvard in 1971.

Disdainful of academic bickering, he instinctively ignored official rebukes, such as those forthcoming when assorted furry creatures ran riot in his office, with results that reached, by his own admission, “circus-like” proportions. “Tree shrews ricocheted across my desk,” he once recalled.

More soberly, he created moving pictures from X-ray plates to give his students insights into how animals walk, trot, gallop, fly and (in the case of monkeys) swing through trees.

In a Harvard career spanning more than 40 years, Jenkins was variously professor of biology, Alexander Agassiz Professor of Zoology and curator of vertebrate palaeontology at the University’s Museum of Comparative Zoology.

His wife, Eleanor, whom he met while he was a student at Princeton, survives him with their son and daughter.

Farish Jenkins, born May 19 1940, died November 11 2012

Source: Article From The telegraph.

New Measurement of Crocodilian Nerves Could Help Scientists Understand Ancient Animals

Crocodilians have nerves on their faces that are so sensitive, they can detect a change in a pond when a single drop hits the water surface several feet away. Alligators and crocodiles use these “invisible whiskers” to detect prey when hunting. Now, a new study from the University of Missouri has measured the nerves responsible for this function, which will help biologists understand how today’s animals, as well as dinosaurs and crocodiles that lived millions of years ago, interact with the environment around them.

Crocodilian facial nerves are much more sensitive than humans. This allows the crocodile to detect minute disruptions in water as they hunt for prey or search for a mate. (Credit: University of Missouri)

Crocodilian facial nerves are much more sensitive than humans. This allows the crocodile to detect minute disruptions in water as they hunt for prey or search for a mate. (Credit: University of Missouri)

“The trigeminal nerve is the nerve responsible for detection of sensations of the face,” said Casey Holliday, assistant professor of anatomy in the MU School of Medicine. “While we’ve known about these sensitive nerves in crocodiles, we’ve never measured the size of the nerve bundle, or ganglion, in their skulls, until now. When compared to humans, this trigeminal nerve in crocodiles is huge.”

The key to this measurement is a specific hole in the skull. The trigeminal nerve is rooted inside the skull, but must travel through a large hole before it branches out to reach the crocodile’s skin on its face. By examining how the skull size, brain size and ganglion size relate to each other, scientists can estimate how sensitive the face is. Eventually, Holliday hopes to measure this nerve in other ancient and contemporary species to learn more about animal behavior.

“Currently, we rely on alligators, crocodiles and birds to provide us with information about how ancient reptiles, such as pre-historic crocodiles and dinosaurs, functioned,” said Holliday, who co-authored the study with doctoral student Ian George. “However, the first thing we have to do is to understand how the living animals function.”

When comparing the size of the hole for the trigeminal nerve found in alligators to that of certain dinosaurs, George says that the hole in the much-larger dinosaur skull is very similar in size or even smaller, which could give scientists more information about how well dinosaurs could detect small sensations on the face. From there, the scientists can start to trace the evolution of this nerve and the mechanism used by crocodiles.

“Some species of ancient crocodiles lived on land and they probably wouldn’t have a use for a sensitive face that can detect disturbances in the water,” George said. “So our next step is to trace back and determine when the nerve got bigger and see how that might have paralleled the animals’ ecology.”

Holliday says that this information will aid future research, including when his team will examine skulls of ancient crocodiles. Understanding this nerve and its functions could also lead to better understanding of the anatomical basis for behavior in many living animals, including fish, electric eels, platypi and humans.

“The same way that we would look at the size of the visual cortex in the brain to understand how well an animal might see, we can now look at the trigeminal nerve in animals to determine how sensitive their skin on their faces is,” Holliday said.

Dwarf Whale Survived Well Into Ice Age

Research from New Zealand’s University of Otago detailing the fossil of a dwarf baleen whale from Northern California reveals that it avoided extinction far longer than previously thought.

Otago Department of Geology PhD student Robert Boessenecker has found that the fossil of the 4-5 meter long Herpetocetus, thought to be the last survivor of the primitive baleen whale family called cetotheres, may be as young as 700,000 years old.

Mr Boessenecker says the previously youngest-known fossils of this whale were from the pre-Ice Age Pliocene epoch; approximately 3 million years ago, a time before many modern marine mammals appeared. Baleen whales of this type were most common much earlier, about 10-15 million years ago.

 

Research detailing the fossil of a dwarf baleen whale, Herpetocetus, from Northern California reveals that it avoided extinction far longer than previously thought. The 4-5 metre long whale, thought to be the last survivor of the primitive baleen whale family called cetotheres, may be as young as 700,000 years old. The previously youngest-known fossils of this whale were from the pre-Ice Age Pliocene epoch; approximately 3 million years ago, a time before many modern marine mammals appeared. Baleen whales of this type were most common much earlier, about 10-15 million years ago. This graphic shows the geologic ages of Herpetocetus and various well known marine and land mammals from California, with a life restoration of Herpetocetus. (Credit: R.W. Boessenecker)

Research detailing the fossil of a dwarf baleen whale, Herpetocetus, from Northern California reveals that it avoided extinction far longer than previously thought. The 4-5 metre long whale, thought to be the last survivor of the primitive baleen whale family called cetotheres, may be as young as 700,000 years old. The previously youngest-known fossils of this whale were from the pre-Ice Age Pliocene epoch; approximately 3 million years ago, a time before many modern marine mammals appeared. Baleen whales of this type were most common much earlier, about 10-15 million years ago. This graphic shows the geologic ages of Herpetocetus and various well known marine and land mammals from California, with a life restoration of Herpetocetus. (Credit: R.W. Boessenecker)

“That this whale survived the great climatic and ecological upheavals of the Ice Age and almost into the modern era is very surprising as nearly all fossil marine mammals found after the end of the Pliocene appear identical to modern species.

“Other baleen whales underwent extreme body size increases in response to the new environment, but this dwarf whale must have still had a niche to inhabit which has only recently disappeared,” he says.

The find indicates that the emergence of the modern marine mammals during the Ice Age may have happened more gradually than currently thought, he says.

The discovery also lends indirect support to a hypothesis about the modern pygmy right whale (Caperea marginata) recently published by Mr Boessenecker’s colleagues Professor Ewan Fordyce and Dr Felix Marx. The pair posited that this enigmatic Southern Ocean whale is not a true right whale but actually a member of the cetothere family and one of the closest relatives of Herpetocetus.

“If their hypothesis is correct, this latest discovery indicates that other close relatives of the pygmy right whale nearly survived to modern times within the Northern Hemisphere.

“In this light, Herpetocetus can be viewed as a Northern Hemisphere equivalent of the pygmy right whale: both are small-bodied with peculiar anatomy, possibly closely related, with feeding habits that are seemingly divergent from other baleen whales.”

All baleen whales lack teeth and instead use baleen to strain small prey like krill and fish from seawater. Many whales, such as humpback and blue whales, gulp enormous amounts of water during lunges, while others such as gray whales filter prey from mud on the seafloor.

Owing to a strange jaw joint, Herpetocetus could not open its mouth more than 35 degrees, unlike any modern baleen whale.

Estimating Impact Forces of Tail Club Strikes by Ankylosaurid Dinosaurs

It has been assumed that the unusual tail club of ankylosaurid dinosaurs was used actively as a weapon, but the biological feasibility of this behaviour has not been examined in detail. Ankylosaurid tail clubs are composed of interlocking vertebrae, which form the handle, and large terminal osteoderms, which form the knob.

 

Methodology/Principal Findings

Computed tomographic (CT) scans of several ankylosaurid tail clubs referred to Dyoplosaurus and Euoplocephalus, combined with measurements of free caudal vertebrae, provide information used to estimate the impact force of tail clubs of various sizes. Ankylosaurid tails are modeled as a series of segments for which mass, muscle cross-sectional area, torque, and angular acceleration are calculated. Free caudal vertebrae segments had limited vertical flexibility, but the tail could have swung through approximately 100° laterally. Muscle scars on the pelvis record the presence of a large M. longissimus caudae, and ossified tendons alongside the handle represent M. spinalis. CT scans showed that knob osteoderms were predominantly cancellous, which would have lowered the rotational inertia of the tail club and made it easier to wield as a weapon.

Ankylosaurid tail reconstructed from ROM 784; ROM 784 lacks the transitional caudal vertebra and the anterior portion of the pelvis. Scale bar equals 1 m. Modified from Arbour et al. (in press). doi:10.1371/journal.pone.0006738.g001

Ankylosaurid tail reconstructed from ROM 784; ROM 784 lacks the transitional caudal vertebra and the anterior portion of the pelvis. Scale bar equals 1 m. Modified from Arbour et al. (in press).
doi:10.1371/journal.pone.0006738.g001

 

Morphology of ankylosaurid tail clubs.  A) UALVP 47273, dorsal view. B) ROM 784 dorsal view and C) posterior view, D) UALVP 16247 dorsal view, E) AMNH 5245 dorsal view, and F) ROM 788 ventral view. doi:10.1371/journal.pone.0006738.g002

Morphology of ankylosaurid tail clubs.
A) UALVP 47273, dorsal view. B) ROM 784 dorsal view and C) posterior view, D) UALVP 16247 dorsal view, E) AMNH 5245 dorsal view, and F) ROM 788 ventral view.
doi:10.1371/journal.pone.0006738.g002

Origins of tail muscles on the pelvis.  A) AMNH 5409 (Euoplocephalus) pelvis, posterior right dorsolateral view. M. ischiocaudalis originates at the distal terminus of the ischium. The origin of M. longissimus caudae is marked by a long, pronounced ridge and rugose area on the lateral aspect of the ilium. The posterior terminus of the ilium is partially reconstructed. B) AMNH 5337 (Euoplocephalus) pelvis, dorsal view, anterior up, showing the posterior terminus of the left ilium. M. iliocaudalis originates from a large knob. C) AMNH 5409, same view as (A), with reconstructed musculature. The muscles are cut posteriorly to show their relationships in cross-section. M. caudofemoralis longus originates on the transverse processes of the free caudal vertebrae, and inserts on the fourth trochanter of the femur (not shown). M. transversospinalis originates and inserts on the neural spines. Scale bars equal 10 cm. Abbreviations are as follows: ca = M. caudofemoralis longus, il = M. iliocaudalis, is = M. ischiocaudalis, lo = M. longissimus caudae, tr = M. transversospinalis. doi:10.1371/journal.pone.0006738.g008

Origins of tail muscles on the pelvis.
A) AMNH 5409 (Euoplocephalus) pelvis, posterior right dorsolateral view. M. ischiocaudalis originates at the distal terminus of the ischium. The origin of M. longissimus caudae is marked by a long, pronounced ridge and rugose area on the lateral aspect of the ilium. The posterior terminus of the ilium is partially reconstructed. B) AMNH 5337 (Euoplocephalus) pelvis, dorsal view, anterior up, showing the posterior terminus of the left ilium. M. iliocaudalis originates from a large knob. C) AMNH 5409, same view as (A), with reconstructed musculature. The muscles are cut posteriorly to show their relationships in cross-section. M. caudofemoralis longus originates on the transverse processes of the free caudal vertebrae, and inserts on the fourth trochanter of the femur (not shown). M. transversospinalis originates and inserts on the neural spines. Scale bars equal 10 cm. Abbreviations are as follows: ca = M. caudofemoralis longus, il = M. iliocaudalis, is = M. ischiocaudalis, lo = M. longissimus caudae, tr = M. transversospinalis.
doi:10.1371/journal.pone.0006738.g008

 

 

Conclusions/Significance

Large knobs could generate sufficient force to break bone during impacts, but average and small knobs could not. Tail swinging behaviour is feasible in ankylosaurids, but it remains unknown whether the tail was used for interspecific defense, intraspecific combat, or both.

Citation: Arbour VM (2009) Estimating Impact Forces of Tail Club Strikes by Ankylosaurid Dinosaurs. PLoS ONE 4(8): e6738. doi:10.1371/journal.pone.0006738

Editor: Andrew Allen Farke, Raymond M. Alf Museum of Paleontology, United States of America

New Evidence Ancient Asteroid Caused Global Firestorm On Earth

A new look at conditions after a Manhattan-sized asteroid slammed into a region of Mexico in the dinosaur days indicates the event could have triggered a global firestorm that would have burned every twig, bush and tree on Earth and led to the extinction of 80 percent of all Earth’s species, says a new University of Colorado Boulder study.

Led by Douglas Robertson of the Cooperative Institute for Research in Environmental Sciences, or CIRES, the team used models that show the collision would have vaporized huge amounts of rock that were then blown high above Earth’s atmosphere. The re-entering ejected material would have heated the upper atmosphere enough to glow red for several hours at roughly 2,700 degrees Fahrenheit — about the temperature of an oven broiler element — killing every living thing not sheltered underground or underwater.

A new CU-Boulder study shows that an asteroid believed to have smacked Earth some 66 million years ago likely caused a global firestorm that led to extensive plant and animal extinctions. (Credit: Illustration courtesy NASA/JPL)

A new CU-Boulder study shows that an asteroid believed to have smacked Earth some 66 million years ago likely caused a global firestorm that led to extensive plant and animal extinctions. (Credit: Illustration courtesy NASA/JPL)

The CU-led team developed an alternate explanation for the fact that there is little charcoal found at the Cretaceous-Paleogene, or K-Pg, boundary some 66 million years ago when the asteroid struck Earth and the cataclysmic fires are believed to have occurred. The CU researchers found that similar studies had corrected their data for changing sedimentation rates. When the charcoal data were corrected for the same changing sedimentation rates they show an excess of charcoal, not a deficiency, Robertson said.

“Our data show the conditions back then are consistent with widespread fires across the planet,” said Robertson, a research scientist at CIRES, which is a joint institute of CU-Boulder and the National Oceanic and Atmospheric Administration. “Those conditions resulted in 100 percent extinction rates for about 80 percent of all life on Earth.”

A paper on the subject was published online this week in the Journal of Geophysical Research-Biogeosciences, a publication of the American Geophysical Union. Co-authors on the study include CIRES Interim Director William Lewis, CU Professor Brian Toon of the atmospheric and oceanic sciences department and the Laboratory for Atmospheric and Space Physics and Peter Sheehan of the Milwaukee Public Museum in Wisconsin.

Geological evidence indicates the asteroid collided with Earth about 66 million years ago and carved the Chicxulub crater in Mexico’s Yucatan Peninsula that is more than 110 miles in diameter. In 2010, experts from 33 institutions worldwide issued a report that concluded the impact at Chicxulub triggered mass extinctions, including dinosaurs, at the K-Pg boundary.

The conditions leading to the global firestorm were set up by the vaporization of rock following the impact, which condensed into sand-grain-sized spheres as they rose above the atmosphere. As the ejected material re-entered Earth’s atmosphere, it dumped enough heat in the upper atmosphere to trigger an infrared “heat pulse” so hot it caused the sky to glow red for several hours, even though part of the radiation was blocked from Earth by the falling material, he said.

But there was enough infrared radiation from the upper atmosphere that reached Earth’s surface to create searing conditions that likely ignited tinder, including dead leaves and pine needles. If a person was on Earth back then, it would have been like sitting in a broiler oven for two or three hours, said Robertson.

The amount of energy created by the infrared radiation the day of the asteroid-Earth collision is mind-boggling, said Robertson. “It’s likely that the total amount of infrared heat was equal to a 1 megaton bomb exploding every four miles over the entire Earth.”

A 1-megaton hydrogen bomb has about the same explosive power as 80 Hiroshima-type nuclear bombs, he said. The asteroid-Earth collision is thought to have generated about 100 million megatons of energy, said Robertson.

Some researchers have suggested that a layer of soot found at the K-Pg boundary layer roughly 66 million years ago was created by the impact itself. But Robertson and his colleagues calculated that the amount of soot was too high to have been created during the massive impact event and was consistent with the amount that would be expected from global fires.

Dusting for prints from a fossil fish to understand evolutionary change

In 370 million-year-old red sandstone deposits in a highway roadcut, scientists have discovered a new species of armored fish in north central Pennsylvania.

 

Fossils of armored fishes like this one, a phyllolepid placoderm, are known for the distinctive ornamentation of ridges on their exterior plates. As with many such fossils, scientists often find the remains of these species as impressions in stone, not as three-dimensional versions of their skeletons. Therefore, in the process of studying and describing this fish’s anatomy, scientists took advantage of a technique that may look a lot like it was stolen from crime scene investigators.

This is a dorsal view of the dermal armor of the newly identified fossil fish species, Phyllolepis thomsoni. - Academy of Natural Sciences of Drexel University

This is a dorsal view of the dermal armor of the newly identified fossil fish species, Phyllolepis thomsoni. – Academy of Natural Sciences of Drexel University

 

In the video (available at http://youtu.be/l7GwvrAaB4U), Dr. Ted Daeschler shows the fossil and a rubber cast made by pouring latex into its natural impression in the rock. Once the latex hardened, Daeschler peeled it out and dusted its surface with a fine powder to better show the edges of the bony plates and the shapes of fine ridges on the fish’s bony armor – a lot like dusting for fingerprints to show minute ridges left on a surface. With this clearer view, Daeschler and colleagues were better able to prepare a detailed scientific description of the new species.

 

This placoderm, named Phyllolepis thomsoni, is one of two new Devonian fish species described by Daeschler in the Bicentennial issue of the Proceedings of the Academy of Natural Sciences of Philadelphia, with different co-authors. The other new species is a lobe-finned fish discovered in northern Canada. This discovery is described at http://drexel.edu/now/news-media/releases/archive/2013/March/Fossil-Species-from-Fish-Eat-Fish-World/.

 

Both the Pennsylvania placoderm and the Canadian lobe-finned fish species are from the late Devonian period, at a time long before dinosaurs walked the Earth – but, geologically speaking, not long before the very first species began to walk on land. Daeschler studies Devonian species in particular to help describe the evolutionary setting that gave rise to the first vertebrate species with limbs. He has dug for Devonian species in Pennsylvania since 1993, and in northern Canada since 1999.

 

Honoring A Rich History of Pennsylvania Paleontology

 

Daeschler, a vice president and associate curator at the Academy of Natural Sciences of Drexel University, and an associate professor in Drexel’s College of Arts and Sciences, and co-author Dr. John A. Long, a leading authority on placoderms from Flinders University in Australia, named the species in honor of Dr. Keith S. Thomson.

 

Thomson, the Executive Officer of the American Philosophical Society, has been a mentor and colleague to many Devonian fossil researchers, including Daeschler. Thomson has formerly held positions including President and CEO of the Academy of Natural Sciences, Director of the Oxford University Museum, and Dean of the Graduate School of Arts and Sciences at Yale University.

 

Asked for comment on the discovery named in his honor, Thomson noted his long professional connection with the Devonian fossil beds in Pennsylvania that Daeschler studies:

 

“The Devonian beds around Renovo PA were worked extensively by my old professor at Harvard, Alfred Sherwood Romer and his associates, in the 1950s. They got some very good material of fishes but gave up on the site as a potential source of the very earliest four-legged vertebrates. In 1965 Romer suggested that I have a go but there had been no major erosion on the sites and therefore nothing much new had become exposed. I moved on to other things, but [in 1993] when Ted asked about possible projects in PA I gave him all the old notebooks, including mine, and off he went. In the intervening period there had been some major roadwork, new exposures were made, and on the Sunday evening of his very first weekend trip Ted came to the house and showed me a part of the shoulder of a tetrapod. Once we had looked at every which way and decided there was no other explanation, he causally reached into his bag and said “in that case, I have another one.” The rest is history — a history of very hard, careful, work, a whole team of collectors, some local, and brilliant discoveries of superb material particularly of fishes of every kind. So I am delighted by the success of this work over the past twenty years and flattered to become associated with it by having a species named after me. (There is a certain symmetry to this as long ago I named one of the species that had been collected by Romer after my wife!)”

 

Note: This story has been adapted from a news release issued by the Drexel University

Massive Extinction Fueled Rise of Crocodiles

A massive extinction between the Triassic and Jurassic eras paved the way for the rise of the crocodiles, new research suggests.

The researchers, who detail their work today (March 26) in the journal Biology Letters, found that although nearly all the crocodilelike archosaurs, known as pseudosuchia, died off about 201 million years ago, the one lineage that survived soon diversified to occupy land and sea. The lineage included the ancestors of all modern crocodiles and alligators.

“Even though almost all the lineages except for one was extinct, the remaining survivors still did well in terms of morphology and body plans and the whole morphological diversity,” said study co-author Olja Toljagic, an evolutionary biology researcher who was at the Ludwig Maximilian University of Munich at the time of the study.

Understanding the traits that allowed certain lineages to thrive could one day help paleontologists untangle one of the greatest mysteries: how dinosaurs survived the extinction unscathed and took over Earth. [Mysterious Earth: 50 Amazing Facts]

Dinosaur counterparts

During the Triassic period, two lines of archosaurs lived in the same environment, which included dinosaurs, and the pseudosuchians, a large group of crocodilelike creatures that had short necks, long snouts and massive skulls.

But around 201 million years ago, volcanic activity or a meteor killed off half the known species on Earth. Just one lineage of pseudosuchians, called the crocodylomorphs, survived. That branch would ultimately give rise to modern-day crocodiles and alligators.

Crocodile line

In order to find out what happened to the pseudosuchians during the mass extinction, Toljagic and her colleague Richard Butler analyzed previous research data on pseudosuchians’ skull characteristics, which could provide details about species diversity.

After doing a systematic analysis, the team found that the single surviving branch not only survived the extinction, but showed great diversity within a few million years after the extinction. These diversified crocodilelike creatures fanned out into different environments–such as swamps, rivers and oceans–during the Triassic period.

Ecological opportunity

The findings suggest that the extinction allowed crocodiles to flourish, said Stephen Brusatte, a paleontologist at the University of Edinburgh, who was not involved in the study.

“That extinction seems to have had a major effect by knocking off many species and then giving new species a chance,” Brusatte told LiveScience.

The next step is to try to piece together a similarly detailed picture for dinosaurs around the same time in order to understand how dinosaurs survived the extinction, he said.

source: article by

Fossil Hunter :Evangelos Matheau-Raven

Evangelos Matheau-Raven is a professional palaeontologist and fossil hunter; who has discovered new species himself. He discovered 4 new chimaera (close relatives of sharks) species found in the Peterborough area  of Callovian, Jurassic age. This discovery had announced inPalAss conference held in Dublin during December 2012. He took his graduation from the University of Hull.

Evangelos hunting for Cretaceous sea urchins at Weybourne, Norfolk

Evangelos hunting for Cretaceous sea urchins at Weybourne, Norfolk

www.fossiliferous.co.uk  is one of the UK’s leading internet fossil dealers. It is run by Evangelos.There are over 1000 different fossil species for sale of high quality and low cost from around the world. . The services and communications  provided by Evangelos are second to none and the feedback on his website is justifying its testimony . As a professional paleontologist ,His 18 years fossil hunting experience is glorified with the membership in Association Of Applied Paleontological Sciences.

 

hunting for Triassic verEvangelos hunting for Triassic vertebrates at Blue Anchor, Somerset

Evangelos hunting for Triassic vertebrates at Blue Anchor, Somerset

For all enquiries and  orders, contact Evangelos on his email at pangaea39@aol.com.

 

The placodonts are fellow Europeans

For around 50 million years, placodonts populated the flat coastal regions of the Tethys Ocean, in modern day Europe and China. The most distinctive feature of these dinosaurs was their teeth: The upper jaw had two rows of flattened teeth – one on the palate and one on the jawbone – while the lower jaw only had one set of teeth ideal for crushing shellfish and crustaceans.

The evolutionary origins of these placodonts remained unclear. However, a new find in a 246-million-year-old sediment layer now sheds light on the origin and phylogenetic development of the placodonts. As the Swiss and German team headed by Torsten Scheyer, a paleontologist at the University of Zurich, reveals the skull found in Winterswijk (Netherlands) is the earliest form of all known placodonts. The juvenile animal lived 246 million years ago. At around two centimeters in size, the skull is exceptionally well preserved and its characteristics set it apart from previous placodont discoveries.

Double row of pointed teeth

The basal-most known placodonts to date have the group’s trademark double row of crushing teeth in the upper jaw. The flattened teeth that give these animals their name only appear in more derived placodonts. “Unlike all the other placodonts discovered to date, the Winterswijk specimen has conical, pointed teeth instead of flattened or ball-shaped crushing ones,” explains Scheyer, “which means the pointed teeth on the lower jaw slotted precisely into the gap between the palate and upper-jawbone teeth when biting.”

This image shows a reconstruction of the juvenile placodont Palatodonta bleekeri. The teeth are striking compared to other placodonts. - Picture: Reconstruction by Jaime Chirinos

This image shows a reconstruction of the juvenile placodont Palatodonta bleekeri. The teeth are striking compared to other placodonts. – Picture: Reconstruction by Jaime Chirinos

The group’s trademark double row of teeth in the upper jaw is proof that the new find is actually a placodont. According to the researchers, the teeth of Palatodonta bleekeri, the scientific name given to the Winterswijk specimen, were specialized in gripping and piercing soft prey. “The double row of teeth in the new find combined with its considerable age lead us to conclude that it is a very early placodont, from which the later forms developed,” says Scheyer. The formation of crushing teeth and the specialization of a diet of shellfish and crustaceans thus developed later within placodont evolution.

European origin confirmed

The small Palatodonta bleekeri skull sheds new light on the ongoing debate on where the placodonts originated: Previous finds suggested origins in the shelf sea areas of either present-day China or Europe. Due to the considerable age of the new Dutch find and its basal form, however, the European origin of the placodonts is deemed confirmed. Scheyer and his colleagues are hoping for further exciting finds in Winterswijk to discover more about the evolution of the placodonts.

Note: This story has been adapted from a news release issued by the University of Zurich

General Patterns of Diversity in Major Marine Microeukaryote Lineages

Microeukaryotes have vital roles for the functioning of marine ecosystems, but still some general characteristics of their current diversity and phylogeny remain unclear. Here we investigated both aspects in major oceanic microeukaryote lineages using 18S rDNA (V4–V5 hypervariable regions) sequences from public databases that derive from various marine environmental surveys. A very carefully and manually curated dataset of 8291 Sanger sequences was generated and subsequently split into 65 taxonomic groups (roughly to Class level based on KeyDNATools) prior to downstream analyses. First, we calculated genetic distances and clustered sequences into Operational Taxonomic Units (OTUs) using different distance cut-off levels. We found that most taxonomic groups had a maximum pairwise genetic distance of 0.25. Second, we used phylogenetic trees to study general evolutionary patterns. These trees confirmed our taxonomic classification and served to run Lineage Through Time (LTT) plots. LTT results indicated different cladogenesis dynamics across groups, with some displaying an early diversification and others a more recent one. Overall, our study provides an improved description of the microeukaryote diversity in the oceans in terms of genetic differentiation within groups as well as in the general phylogenetic structure. These results will be important to interpret the large amount of sequence data that is currently generated by High Throughput Sequencing technologies.

Citation: Pernice MC, Logares R, Guillou L, Massana R (2013) General Patterns of Diversity in Major Marine Microeukaryote Lineages. PLoS ONE 8(2): e57170. doi:10.1371/journal.pone.0057170

Editor: Jonathan H. Badger, J. Craig Venter Institute, United States of America