Benson R.B.J.,University of Oxford |
Evans M.,New Walk Museum and Art Gallery |
Smith A.S.,Nottingham Natural History Museum |
Sassoon J.,University of Bristol |
And 3 more authors.
PLoS ONE | Year: 2013
Pliosaurids were a long-lived and cosmopolitan group of marine predators that spanned 110 million years and occupied the upper tiers of marine ecosystems from the Middle Jurassic until the early Late Cretaceous. A well-preserved giant pliosaurid skull from the Late Jurassic Kimmeridge Clay Formation of Dorset, United Kingdom, represents a new species, Pliosaurus kevani. This specimen is described in detail, and the taxonomy and systematics of Late Jurassic pliosaurids is revised. We name two additional new species, Pliosaurus carpenteri and Pliosaurus westburyensis, based on previously described relatively complete, well-preserved remains. Most or all Late Jurassic pliosaurids represent a globally distributed monophyletic group (the genus Pliosaurus, excluding 'Pliosaurus' andrewsi). Despite its high species diversity, and geographically widespread, temporally extensive occurrence, Pliosaurus shows relatively less morphological and ecological variation than is seen in earlier, multi-genus pliosaurid assemblages such as that of the Middle Jurassic Oxford Clay Formation. It also shows less ecological variation than the pliosaurid-like Cretaceous clade Polycotylidae. Species of Pliosaurus had robust skulls, large body sizes (with skull lengths of 1.7-2.1 metres), and trihedral or subtrihedral teeth suggesting macropredaceous habits. Our data support a trend of decreasing length of the mandibular symphysis through Late Jurassic time, as previously suggested. This may be correlated with increasing adaptation to feeding on large prey. Maximum body size of pliosaurids increased from their first appearance in the Early Jurassic until the Early Cretaceous (skull lengths up to 2360 mm). However, some reduction occurred before their final extinction in the early Late Cretaceous (skull lengths up to 1750 mm). © 2013 Benson et al.
Smith A.S.,Nottingham Natural History Museum
Palaeontologia Electronica | Year: 2015
The holotype specimen of ‘Plesiosaurus’ megacephalus Stutchbury, 1846 (BRSMG Cb 2335) was destroyed in an air raid on Bristol during WWII. The specimen comprised a complete skeleton from the Triassic-Jurassic boundary of Street-on-the- Fosse, Somerset, UK. Plaster casts of the skull and right forelimb produced prior to its destruction, in conjunction with historical photographs and original descriptions, provide three-dimensional anatomical data for a modern systematic diagnosis of the taxon. A previously proposed neotype specimen (LEICS G221.1851) is therefore regarded as a referred specimen. Detailed comparison with other Lower Jurassic plesiosaurians demonstrates that ‘Plesiosaurus’ megacephalus is a distinct taxon, separate from Rhomaleosaurus sensu stricto and Eurycleidus arcuatus, and so a new genus is erected to accommodate it: Atychodracon gen. nov. The clarification and description of Atychodracon megacephalus is a vital step towards understanding the diversity and resolving the systematics of large-bodied plesiosaurians from the Triassic- Jurassic boundary. © Palaeontological Association April 2015.
Prs-Jones R.P.,Bird Group |
Russell D.G.D.,Bird Group |
Wright S.,Nottingham Natural History Museum
Bulletin of the British Ornithologists' Club | Year: 2015
The two syntypes of California Quail Tetrao californicus Shaw, 1798, were deposited in the British Museum in the 1790s, but were last documented as present in the late 1860s and had subsequently been presumed no longer extant. In 2004, they were re-discovered in Nottingham Natural History Museum, to which they must have been inadvertently passed as 'duplicates' in the late 1800s, and have now been returned to the Natural History Museum, Tring, on extended renewable loan. During research regarding these Archibald Menzies specimens, new insight was gained into hitherto confusing reference details on the label of his type specimen of California Condor Vultur californianus Shaw, 1797.
Liu S.,Georgia Institute of Technology |
Smith A.S.,Nottingham Natural History Museum |
Gu Y.,Georgia Institute of Technology |
Tan J.,Georgia Institute of Technology |
And 2 more authors.
PLoS Computational Biology | Year: 2015
Plesiosaurians are an extinct group of highly derived Mesozoic marine reptiles with a global distribution that spans 135 million years from the Early Jurassic to the Late Cretaceous. During their long evolutionary history they maintained a unique body plan with two pairs of large wing-like flippers, but their locomotion has been a topic of debate for almost 200 years. Key areas of controversy have concerned the most efficient biologically possible limb stroke, e.g. whether it consisted of rowing, underwater flight, or modified underwater flight, and how the four limbs moved in relation to each other: did they move in or out of phase? Previous studies have investigated plesiosaur swimming using a variety of methods, including skeletal analysis, human swimmers, and robotics. We adopt a novel approach using a digital, three-dimensional, articulated, free-swimming plesiosaur in a simulated fluid. We generated a large number of simulations under various joint degrees of freedom to investigate how the locomotory repertoire changes under different parameters. Within the biologically possible range of limb motion, the simulated plesiosaur swims primarily with its forelimbs using an unmodified underwater flight stroke, essentially the same as turtles and penguins. In contrast, the hindlimbs provide relatively weak thrust in all simulations. We conclude that plesiosaurs were forelimb-dominated swimmers that used their hind limbs mainly for maneuverability and stability. © 2015 Liu et al.
PubMed | Georgia Institute of Technology and Nottingham Natural History Museum
Type: Journal Article | Journal: PLoS computational biology | Year: 2015
Plesiosaurians are an extinct group of highly derived Mesozoic marine reptiles with a global distribution that spans 135 million years from the Early Jurassic to the Late Cretaceous. During their long evolutionary history they maintained a unique body plan with two pairs of large wing-like flippers, but their locomotion has been a topic of debate for almost 200 years. Key areas of controversy have concerned the most efficient biologically possible limb stroke, e.g. whether it consisted of rowing, underwater flight, or modified underwater flight, and how the four limbs moved in relation to each other: did they move in or out of phase? Previous studies have investigated plesiosaur swimming using a variety of methods, including skeletal analysis, human swimmers, and robotics. We adopt a novel approach using a digital, three-dimensional, articulated, free-swimming plesiosaur in a simulated fluid. We generated a large number of simulations under various joint degrees of freedom to investigate how the locomotory repertoire changes under different parameters. Within the biologically possible range of limb motion, the simulated plesiosaur swims primarily with its forelimbs using an unmodified underwater flight stroke, essentially the same as turtles and penguins. In contrast, the hindlimbs provide relatively weak thrust in all simulations. We conclude that plesiosaurs were forelimb-dominated swimmers that used their hind limbs mainly for maneuverability and stability.
News Article | December 17, 2015
A replica of the Plesiosaur "Tuarangisaurus Cabazai" made from polyurethane foam is pictured on display at the Argentine Natural Sciences Museum in Buenos Aires in this file photo from July 1, 2013. REUTERS/Enrique Marcarian/Files More WASHINGTON (Reuters) - Plesiosaurs, marine reptiles that thrived in the world's seas when dinosaurs ruled the land, swam much like penguins by using their flippers to "fly" underwater, scientists said on Thursday, resolving a debate that began nearly two centuries ago. Plesiosaurs had four large flippers, and many had remarkably long necks. They lived from about 200 million years ago to 66 million years ago, disappearing in the same mass extinction that doomed the dinosaurs. Nessie, Scotland's mythical Loch Ness monster, often is portrayed as looking like a plesiosaur. The researchers conducted a series of computer simulations based on the anatomy of a plesiosaur from 180 million years ago called Meyerasaurus to find the most effective swimming strategy for this body design. The method that produced the fastest forward speed was flapping the two front flippers up and down in an underwater flying motion similar to penguins and sea turtles. "What was unexpected was that no matter what motion we simulated for the back flippers, they could not substantially contribute to the plesiosaur's forward motion," said Georgia Institute of Technology computer science professor Greg Turk. The back flippers were probably used to steer and provide stability, said the researchers, whose work was published in the journal PLOS Computational Biology. Plesiosaurs, which ate fish and squid, came in various shapes and sizes, some with shorter necks and others with lengthy ones like Elasmosaurus, a creature about 46 feet (14 meters) long. Meyerasaurus, unearthed in Germany, measured 10 feet (3 meters) long. "The plesiosaurs were a highly successful group of large predatory creatures, yet we didn't know how they swam. Their body plan wasn't an isolated fluke, pardon the pun, because the history of plesiosaurs stretched over 135 million years and dozens of species," Turk said. Plesiosaur fossils were first described in 1824. Ever since, scientists have debated how they swam. "Plesiosaur swimming has remained a mystery for almost 200 years because it is difficult to determine how an extinct animal with a unique body plan moved," said paleontologist Adam Smith of Britain's Nottingham Natural History Museum. There have been some competing hypotheses, Smith added, with some researchers suggesting plesiosaurs moved their limbs mostly backwards and forwards, in a rowing motion. The underwater flying method is unusual because swimming creatures, including most fish and whales, tend to generate thrust using their tails, Smith said. "Plesiosaurs are truly weird and unique creatures," Smith said.
News Article | December 18, 2015
Ancient marine reptiles called plesiosaurs likely swam like penguins, relying on their front flippers for forward propulsion. More The ancient, four-flippered plesiosaur didn't swim like a fish, whale or even an otter — but instead like a penguin, a new study finds. Plesiosaurs, giant marine reptiles that lived during the dinosaur age, likely propelled themselves forward underwater by flapping their two front flippers, much like penguins do today, the researchers said. The paleo-giants probably didn't rely much on their back flippers for propulsion, as that movement would've only marginally increased their speed, computer simulations showed. "This is the first time plesiosaur locomotion has been simulated with computers, so our study provides exciting new information on how these unusual extinct animals may have swum," said study co-author Adam Smith, a curator of natural sciences at Wollaton Hall, Nottingham Natural History Museum in the United Kingdom. [Photos: Uncovering One of the Largest Plesiosaurs on Record] The study began when Jie Tan, a graduate student at the Georgia Institute of Technology, began creating computer models and simulations that captured the movements of modern animals. After designing virtual simulations of moving frogs, turtles, eels and manta rays, Tan turned to imaginary creatures. But he wanted another challenge, so he chose an extinct beast for his next project, said study senior author Greg Turk, a professor of computer science at Georgia Tech. Plesiosaur locomotion has puzzled scientists since the reptiles were first discovered in 1824, because there aren't any modern animals that look like them. Even marine turtles, which have two large front flippers, are no match, because unlike plesiosaurs, turtles have tiny back flippers."I did some poking around and found that plesiosaurs have this weird body plan," Turk said. "There isn't any agreement in the paleontology literature about how they swam." To investigate, the team of computer scientists and paleontologists built a computer model based on Meyerasaurus victor, an 11-foot-long (3.4 meters) plesiosaur discovered in a Lower Jurassic formation in Germany. The scientists placed pivot points on the model's legs wherever the real-life M. victor had joints, but they kept the model's neck and tail rigid, Turk said. "We weren't looking for what contribution the tail motion had," Turk told Live Science. "There are hints that some plesiosaurs might have had a little bit of a tail fin, but that's not something we looked into." The researchers ran about 2,000 simulations to identify the most efficient way the plesiosaur could have swum. In the end, they found that if plesiosaurs flapped their front flippers up and down, the animals could have efficiently propelled themselves forward with every up and down stroke. "Plesiosaurs flew underwater using their winglike flippers," Smith said. "The front flippers were the powerhouse providing most of the thrust, while the rear flippers provided less thrust and may have been used for stability and steering instead." This technique, if accurate, clearly worked for plesiosaurs; the reptiles reigned as marine apex predators for 135 million years, until the asteroid event wiped them out some 66 million years ago, the researchers said. The study was published online yesterday (Dec. 17) in the journal PLOS Computational Biology. Copyright 2015 LiveScience, a Purch company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.