WFS

Formation of sedimentary layers of white clay, Tamilnadu, India

Fossil site for wood fossils, Tamilnadu, India

Fossil site in Kerala, India

Fossil wood park maintained by geological survey of India at Tamilnadu

Cretaceous fossil sites india

Fossils in rack:-Cyad

Fossils in rack:-echiniderms

Fossils in rack:-Rastellum sp

Pre-historic seabed, Cretaceous period

Quantifying Rates of Evolutionary Adaptation in Response to Ocean Acidification

October 14th, 2012

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The global acidification of the earth’s oceans is predicted to impact biodiversity via physiological effects impacting growth, survival, reproduction, and immunology, leading to changes in species abundances and global distributions. However, the degree to which these changes will play out critically depends on the evolutionary rate at which populations will respond to natural selection imposed by ocean acidification, which remains largely unquantified. Here we measure the potential for an evolutionary response to ocean acidification in larval development rate in two coastal invertebrates using a full-factorial breeding design. We show that the sea urchin species Strongylocentrotus franciscanushas vastly greater levels of phenotypic and genetic variation for larval size in future CO₂conditions compared to the mussel species Mytilus trossulus. Using these measures we demonstrate that S. franciscanus may have faster evolutionary responses within 50 years of the onset of predicted year-2100 CO₂ conditions despite having lower population turnover rates. Our comparisons suggest that information on genetic variation, phenotypic variation, and key demographic parameters, may lend valuable insight into relative evolutionary potentials across a large number of species.

Jennifer M. Sunday¹^*, Ryan N. Crim², Christopher D. G. Harley², Michael W. Hart¹

1 Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada, 2 Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada

“Thunder Thighs” Dinosaur Thrashed Predators to Death?

October 13th, 2012

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A newfound dinosaur species that used its “exceptionally powerful” thighs to kick predators likely had a bad temper to boot, one expert says.

The 46-foot-long (14-meter-long) Brontomerus mcintoshi had an immense blade on its hipbones where strong muscles would have attached, according to a new study.

“These things don’t happen by accident—this is something that’s clearly functional,” said study co-author Mathew Wedel.

The team suspects the dinosaur—a type of sauropod, or plant-eating, four-legged lumberer—used its massive legs to either maneuver over hilly ground or deliver “good, hard” kicks to predators, said Wedel, assistant professor of anatomy at Western University of Health Sciences in Pomona, California.

Brontomerus

Brontomerus—”thunder thighs” in Greek—may have even attacked like a modern-day chicken, relentlessly kicking and stomping pursuers to death, he added.

“I could only imagine how ill-tempered these sauropods would have been,” Wedel said—as are most birds, dinosaurs’ modern-day descendants.

In both cases, “you’ve got a little brain, you’re permanently paranoid about all these meat-eaters around, and you’re trying to protect your young.”

“Extreme” Dinosaur Roamed Prehistoric Serengeti

Thunder thighs’ bones were first found in 1994, when scientists rescued two partial skeletons of the then unidentified dinosaur from a fossil quarry that had otherwise been looted in eastern Utah.

When Wedel and colleagues examined the bones in 2007, they realized they’d found a new species—and an “extreme” one at that, Wedel said. For instance, the shapes of the newfound species’ bones showed it had the largest leg muscles of any sauropod yet found.

B. mcintoshi likely needed such extreme defenses to fight off “terrifying” predators such as Deinonychus (picture) and Utahraptor (picture), raptors that lived alongside the plant-eater about 110 million years ago in the earlyCretaceous period, he said.

The prehistoric animals roamed a landscape that would have resembled Africa’s Serengeti, laced with rivers and mudholes and distinguished by vast, dry upland areas, Wedel noted. Herds of cowlike plant-eaters called Tenontosauruswould have dotted the plains.

“If I could shoot you back in a time machine, it would have been like going on safari, except you’d want something more robust than a Land Rover—maybe a tank,” he said.

“The sauropods were probably beautiful animals if you were a long way away with binoculars,” he added.

“But up close, [they were] probably a nightmare.”

Taken From : Article of Christine Dell’Amore National Geographic News

The thunder thighs dinosaur is described in the most recent issue of the journalActa Palaeontologica Polonica.

Illustration courtesy Francisco Gascó, Mike Taylor, and Matt Wedel

Paleotemperature Proxies from Leaf Fossils Reinterpreted in Light of Evolutionary History

October 12th, 2012

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Present-day correlations between leaf physiognomic traits (shape and size) and climate are widely used to estimate paleoclimate using fossil floras. For example, leaf-margin analysis estimates paleotemperature using the modern relation of mean annual temperature (MAT) and the site-proportion of untoothed-leaf species (NT). This uniformitarian approach should provide accurate paleoclimate reconstructions under the core assumption that leaf-trait variation principally results from adaptive environmental convergence, and because variation is thus largely independent of phylogeny it should be constant through geologic time. Although much research acknowledges and investigates possible pitfalls in paleoclimate estimation based on leaf physiognomy, the core assumption has never been explicitly tested in a phylogenetic comparative framework. Combining an extant dataset of 21 leaf traits and temperature with a phylogenetic hypothesis for 569 species-site pairs at 17 sites, we found varying amounts of non-random phylogenetic signal in all traits. Phylogenetic vs. standard regressions generally support prevailing ideas that leaf-traits are adaptively responding to temperature, but wider confidence intervals, and shifts in slope and intercept, indicate an overall reduced ability to predict climate precisely due to the non-random phylogenetic signal. Notably, the modern-day relation of proportion of untoothed taxa with mean annual temperature (NT-MAT), central in paleotemperature inference, was greatly modified and reduced, indicating that the modern correlation primarily results from biogeographic history. Importantly, some tooth traits, such as number of teeth, had similar or steeper slopes after taking phylogeny into account, suggesting that leaf teeth display a pattern of exaptive evolution in higher latitudes. This study shows that the assumption of convergence required for precise, quantitative temperature estimates using present-day leaf traits is not supported by empirical evidence, and thus we have very low confidence in previously published, numerical paleotemperature estimates. However, interpreting qualitative changes in paleotemperature remains warranted, given certain conditions such as stratigraphically closely-spaced samples with floristic continuity.

Stefan A. Little¹^,²^*, Steven W. Kembel³, Peter Wilf¹

1 Department of Geosciences, Pennsylvania State University, University Park, Pennsylvania, United States of America, 2 Department of Plant Sciences, University of California Davis, Davis, California, United States of America, 3Center for Ecology and Evolutionary Biology, University of Oregon, Eugene, Oregon, United States of America

New Fossils Suggest Ancient Origins of Modern-Day Deep-Sea Animals

October 11th, 2012

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A collection of fossil animals discovered off the coast of Florida suggests that present day deep-sea fauna like sea urchins, starfish and sea cucumbers may have evolved earlier than previously believed and survived periods of mass extinctions similar to those that wiped out the dinosaurs.

The full results are published Oct. 10 in the open access journal PLOS ONE by Ben Thuy and colleagues from the University of Göttingen, Germany.

deep sea fauna

Previously, researchers believed that these present-day animals evolved in the relatively recent past, following at least two periods of mass extinction caused by changes in their oceanic environment. The new fossil collection described in this study predates the oldest known records of the present-day fauna. “We were amazed to see that a 114 million year old deep-sea assemblage was so strikingly similar to the modern equivalents,” says lead author Ben Thuy.

According to the authors, this evidence shows that the ancestors of modern deep-sea animals have lived in these deep waters for much longer than previously thought. That this collection of fossils appears to have survived several drastic changes in oceanic climates also suggests that deep-sea biodiversity may be more resilient than shallow-water life forms, and more resistant to extinction events than previously thought.

Marine Worms Reveal the Deepest Evolutionary Patterns

October 10th, 2012

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Scientists from the universities of Bath and Lincoln have revealed new findings on the evolutionary relationships and structure of priapulids — a group of carnivorous mud-dwelling worms living in shallow marine waters.

The research, carried out by evolutionary biologists Dr Matthew Wills, Dr Sylvain Gerber, Mr Martin Hughes (all University of Bath) and Dr Marcello Ruta (University of Lincoln), features in the October issue of Journal of Evolutionary Biology.

Priapulid. (Credit: Bruno Vellutini, Sars Centre, Bergen Norway)

Dr Wills first pioneered a study on existing and extinct priapulids in 1998. Fourteen years on, the team looked at a new and expanded data set of anatomical features to see how knowledge of these worms has been affected by new fossil finds.

He explained: “The fossils from the Cambrian period can cause a real headache for evolutionary biologists. Instinct tells us to expect simple organisms evolving over time to become increasingly more complex. However during the Cambrian period there was an apparent explosion of different major groups of animals, all appearing simultaneously in the fossil record. We looked at priapulid worms, which were among the first ever predators. What’s remarkable is that they had already evolved into a diverse array of forms — comparable to the morphological variety of their living cousins — when we first encounter them in the Cambrian fossil record. It’s precisely this apparent explosion of anatomical diversity that vexed Darwin and famously attracted the attention of Harvard biologist Stephen Jay Gould.”

Dr Ruta, from the School of Life Sciences at the University of Lincoln, continued: “Our work has shown that despite many new fossil finds, including many from China in the last decade, the picture remains largely unchanged. This is really important because the fossil record is notoriously incomplete. It is often difficult to know whether a pattern is just an artifact of this incompleteness, or biologically meaningful. Our study resolutely confirms the latter. Priapulids are fascinating animals with much potential in evolutionary studies. They have a long history, with the earliest known species being 505 million years old, and with some of their extinct relatives being even older. They were important components of ancient bottom-dwelling marine invertebrate communities, and their predatory habits are well documented in the fossil record. However, for all their abundance and diversity, priapulids are a remarkable and often cited example of a morphologically conservative group, their overall shape and proportions having changed relatively little during their history. This research will help us to understand evolutionary patterns in ‘deep time’. This is looking at the tempo (evolutionary rates) and mode (the study of the way, manner or pattern of evolution) to uncover the ancient events when organisms first began to diversify and break from one another. For example, what makes a mammal a mammal and so on.”

The research gives prominence to the importance of an adequate and unbiased inclusion of data, where possible, from both fossil and living species in assembling evolutionary family trees. Fossils inform our understanding of evolutionary patterns and processes, and show unique morphological traits that are no longer observed in living species.

Dr Ruta added: “Detailed scrutiny of other groups of organisms is needed, in order to decipher the rate at which structural, functional and ecological changes occur and how acquisition of new traits impact on group diversification. Ultimately, combined results from these investigations will offer a solid framework for understanding the very roots of Life’s grandeur and the astounding variety of species alive today.”

Unique Ancient Spider Attack Preserved in Amber

October 9th, 2012

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Researchers have found what they say is the only fossil ever discovered of a spider attack on prey caught in its web — a 100 million-year-old snapshot of an engagement frozen in time.

spider attack

The extraordinarily rare fossils are in a piece of amber that preserved this event in remarkable detail, an action that took place in the Hukawng Valley of Myanmar in the Early Cretaceous between 97-110 million years ago, almost certainly with dinosaurs wandering nearby.

Aside from showing the first and only fossil evidence of a spider attacking prey in its web, the piece of amber also contains the body of a male spider in the same web. This provides the oldest evidence of social behavior in spiders, which still exists in some species but is fairly rare. Most spiders have solitary, often cannibalistic lives, and males will not hesitate to attack immature species in the same web.

“This juvenile spider was going to make a meal out of a tiny parasitic wasp, but never quite got to it,” said George Poinar, Jr., a professor emeritus of zoology at Oregon State University and world expert on insects trapped in amber. He outlined the findings in a new publication in the journal Historical Biology.

“This was a male wasp that suddenly found itself trapped in a spider web,” Poinar said. “This was the wasp’s worst nightmare, and it never ended. The wasp was watching the spider just as it was about to be attacked, when tree resin flowed over and captured both of them.”

Spiders are ancient invertebrates that researchers believe date back some 200 million years, but the oldest fossil evidence ever found of a spider web is only about 130 million years old. An actual attack such as this between a spider and its prey caught in the web has never before been documented as a fossil, the researchers said.

The tree resin that forms amber is renowned for its ability to flow over insects, small plants and other life forms, preserving them in near perfection before it later turns into a semi-precious stone. It often gives scientists a look into the biology of the distant past. This spider, which may have been waiting patiently for hours to capture some prey, was smothered in resin just a split second before its attack.

This type of wasp, Poinar said, belongs to a group that is known today to parasitize spider and insect eggs. In that context, the attack by the spider, an orb-weaver, might be considered payback.

Both the spider and the wasp belong to extinct genera and are described in the paper. At least 15 unbroken strands of spider silk run through the amber piece, and on some of these the wasp was ensnared.

Its large and probably terrified eyes now stare for eternity at its attacker, moving in for the kill.

Which Came First, Shells or No Shells? Contrary Story of Ancient Mollusk

October 8th, 2012

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fossil unearthed in Great Britain may end a long-running debate about the mollusks, one of life’s most diverse invertebrate groups: Which evolved first, shelled forms like clams and snails, or their shell-less, worm-like relatives?

The small new fossil, found in marine rocks along the English-Welsh border, provides the best fossil evidence yet that the simpler worm-like mollusks evolved from their more anatomically complex shelled brethren, rather than the other way around.

A small new fossil found in Great Britain provides the best fossil evidence yet that simpler worm-like mollusks evolved from their more anatomically complex shelled brethren, rather than the other way around.Scientists have discovered a rare fossil called Kulindroplax, the missing link between two mollusc groups, which is revealed in a 3D computer model. (Credit: Image courtesy of Imperial College LondonImage courtesy of Yale University)

The discovery reinforces previous findings from molecular sequencing studies and helps clarify the evolutionary relationships of mollusks, a broad category that includes not only oysters and mussels but also slugs, squids and octopuses.

“This is a kind of missing link with a worm-like body, bearing a series of shells like those of a chiton or coat-of-mail shell,” said Derek E. G. Briggs, director of the Yale Peabody Museum of Natural History and one of the paleontologists who studied the new fossil, Kulindroplax perissokomos. The researchers report their findings online Oct. 3 in the journal Nature.

The evolutionary relationships of worm-like mollusks, known as Aplacophora, has been a subject of controversy. Previously thought to be a product of the explosion of diversity during the early Cambrian period, they are now shown to have evolved probably 40-50 million years ago by losing shells like those onKulindroplax.

Kulindroplax represents the first mollusk with an unambiguous combination of valves, or exterior shells, and a worm-like body, said Mark D. Sutton of Imperial College London, the paper’s lead-author.

The researchers found the specimen of Kulindroplax more than 10 years ago in the Herefordshire fossil deposit, a rich assemblage of ancient marine life forms more than 400 million years old. About 2 cm wide and 4 cm long, Kulindroplax was buried in volcanic ash deposited on the sea floor. The researchers later reconstructed its three-dimensional shape using computer software, revealing both form and structure in fine detail. In addition to its seven shells, Kulindroplax had a dense covering of spicules over the rest of the body, which it probably used to gain purchase as it crawled on the muddy sea bed.

Kulindroplax is coined from the Greek words for a cylinder and a plate, referring to the rounded body with its series of shells.

The other authors of the paper are David J. Siveter of the University of Leicester, Derek J. Siveter of the University of Oxford and Julia D. Sigwart of Queen’s University, Belfast.

Support for the research was provided by the Natural Environmental Research Council.

Violent Life of Monogenetic Volcanoes

October 7th, 2012

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A new study in the journal Geology is shedding light on the brief but violent lives of maar-diatreme volcanoes, which erupt when magma and water meet in an explosive marriage below the surface of Earth.

Maar-diatremes belong to a family of volcanoes known as monogenetic volcanoes. These erupt just once before dying, though some eruptions last for years. Though not particularly famous, monogenetic volcanoes are actually the most common form of land-based volcano on the planet.

Lunar Crater maar in Nevada, a maar-diatreme volcano. A new study is shedding light on the explosive mechanism of these volcanoes, which erupt just once before dying. (Credit: Greg

Despite their number, monogenetic volcanoes are poorly understood, said Greg A. Valentine, PhD, University at Buffalo geology professor.

He is lead author of the new Geologypaper, which provides a novel model for describing what happens underground when maar-diatremes erupt. The research appeared online Sept. 18.

“The hazards that are associated with these volcanoes tend to be localized, but they’re still significant,” Valentine said. “These volcanoes can send ash deposits into populated areas. They could easily produce the same effects that the one in Iceland did when it disrupted air travel, so what we’re trying to do is understand the way they behave.”

Previously, scientists theorized that maar-diatreme eruptions consisted, underground, of a series of explosions that took place as magma reacted violently with water. With each explosion, the subterranean water table would fall, driving the next explosion even deeper.

Taking into account new geological evidence, Valentine and volcanologist James D.L. White of New Zealand’s University of Otago revise this model.

In Geology, they propose that maar-diatreme eruptions consist not of ever-deepening explosions, but of explosions occurring simultaneously over a range of depths.

Under this new paradigm, deep explosions break up buried rock thousands of feet below ground and push it upward. Shallow explosions eject some of this debris from the volcano’s depths, but expel far larger quantities of shallow rock.

This model fits well with recent field studies that have uncovered large deposits of shallow rock ringing maar-diatreme volcanoes, with only small amounts of deeper rock present. This was the case, for example, at two sites that Valentine examined at the San Francisco Volcanic Field in Arizona.

White and Valentine’s description of the eruptive process also corresponds well with White’s investigations into the “plumbing” of maar-diatreme volcanoes, the conduits that carry magma toward the surface. These conduits become visible over time as a landscape erodes away, and the main “pipe” — called a diatreme — often shows evidence of explosions, including zones of broken-up rock, at a range of depths.

Such findings contradict the older model that White and Valentine argue against.

According to the old model, Valentine explained, ever-deepening explosions should cause shallow rocks to be ejected from the mouth of the volcano first, followed by deposits of deeper and deeper rock fragments. But this isn’t what scientists are finding when they analyze geological clues at volcanic sites.

The old model doesn’t account for the fact that even when scientists find deep rock fragments at maar-diatreme sites, these bits of rock are mixed mostly with shallow fragments. The old model also doesn’t match with White’s observations indicating that explosions occur at essentially every depth.

The new model uses the strengths of the old model but accounts for new data. The results give scientists a better basis for estimating the hazards associated with maar-diatreme volcanoes, Valentine said.

Flexibility along the Neck of the Neogene Terror Bird Andalgalornis steulleti (Aves Phorusrhacidae)

October 6th, 2012

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Neck length and neck posture are both relevant to give the appropriate position of the head during all kinds of behaviors . For activities such as mating or defense the neck has the ability to perform more complex movements linked to the cervical morphology. The head centre of gravity over the feet is deeply correlated with the erect posture on land and also depends on the movements of the neck. In normal stance birds (and all amniotes) maintain vertical its cervical column .

Size, morphology and number of vertebrae are three important variables involved in the motion of the neck . Birds have a highly variable number of cervical vertebrae (9–11 in some parrots, 23–25 in swans) but, whatever the number, their necks look shorter or longer depending on the neck-folding (Fig. 1). All birds have a flexible “S” shaped neck but the flexion capacity varies between them and for sure, the arrangement is a consequence of an intricate system made by muscles, ligaments and complex articulations. As flexion increases, the distance between the head and the thorax will be shorter and, under these circumstances the external profile of the animal’s neck region shortens .

thumbnail Figure 1. Comparison between external neck guises in selected birds.

1 toucan, 2 owl, 3 eagle, 4 tinamous, 5 seagull, 6 seriema, 7 ibis, 8 egret, 9 greater rhea, 10 swan.

Each vertebra articulates with the adjacent through a saddle-shaped region (articulatio intercorporalisin the sense of located at the base of the vertebral body (corpus vertebrae) (Fig. 2) and two additional sliding surfaces located in the top (articulatio zygapophysialis cranialis and caudalis) . This morphology allows large dorsoventral movements of the neck but prevents rotation, which is generally small.

thumbnail Figure 2. Features of the 5th cervical vertebrae in the seagull Larus sp.

A, cranial view; B, lateral view; C, dorsal view.

Boas divided the cervical column of birds in three main regions according to the dorsoventral bending: the most rostral is the region 1 in which ventral flexion is prevalent, region 2 in which dorsal flexion prevails and region 3 in which both dorsal and ventral flexion are limited. The boundaries between these regions are given by transitional vertebrae that have a particular morphology. Knowing the vertebral morphology of each region one can infer what kind of movements could be possible.

Andalgalornis steulleti (Kraglievich 1931), from the upper Miocene–lower Pliocene (≈6 million years ago) of Argentina, was a medium-sized patagornithine phorusrhacid of about 40 kg body mass, 1.4 m height, and 370 mm total skull length . Together with the long legs, the atypical large skull with high and narrow beak is a characteristic feature of all phorusrhacids . The Phorusrhacidae are often regarded as apex predators of the South American Tertiary environments sharing this role with large now-extinct marsupials . Popularly known as “terror birds” (a name applied at least to the giant forms) there are no close modern analogs which facilitate interpretations about their biology.

Here we analyze the flexion patterns of the neck of Andalgalornis based on the neck vertebrae morphology and biometrics. Complete columns among phorusrhacids remains are scare and in most cases in those specimens where the column is quite complete, the vertebrae are severely damaged. So far, the column of Andalgalornis is the most complete and well preserved known of a terror bird. The study here is the first interpretation of the potential performance of the neck of Andalgalornis in its entirety and we considered this an important starting point to understand and reconstruct the entire neck of other phorusrhacids from which the neck is unknown or severely damaged.

The vertebral morphology of Andalgalornis has not been extensively described in the literature. In their original description of the only complete column known for the species, Patterson and Kraglievich recognized the presence of 17 presynsacral vertebrae (11 cervicals, 2 cervicodorsals and 4 dorsals) of which 13 form the neck. Their description is limited to the size comparison of the vertebral body and only in a few vertebrae did they also compare the height of the neural spine.

We will dwell on the comparison between several extant birds of different size and habits in order to establish a correlation between cervical morphology and mode of life. Such anatomical analysis is not available for any phorusrhacid, while it is a first requirement for any quantitative analysis in comparative, functional or ecological morphology.

Research work of : Claudia P. Tambussi¹^,²^*, Ricardo de Mendoza¹, Federico J. Degrange²^,³, Mariana B. Picasso¹

1 División Paleontología Vertebrados, Museo de La Plata, Paseo del Bosque s/n, La Plata, Argentina, 2 Consejo Nacional de Investigaciones Científicas y Técnicas CONICET, Ciudad Autónoma de Buenos Aires, Argentina, 3 Centro de Investigaciones en Ciencias de la Tierra CICTERRA, Córdoba, Argentina .Published in PLOs One .

Bizarre Species of Miniature Dinosaur Identified

October 5th, 2012

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Not every dinosaur grew up to be a mighty predator like Tyrannosaurus rex or a hulking vegan like Apatosaurus. A few stayed small, and some of the smallest dinosaurs that ever lived — tiny enough to nip at your heels — were among the first to spread across the planet more than 200 million years ago.

Todd Marshall

With jaws only one inch in length,the plant-eating Pegomastax is one of the smallest dinosaurs ever discovered.

Some heterodontosaurids grew to less than 2 feet in length and rank as dwarfs in the dinosaur era.

Tyler Keillor

Skin, scales and quills were added to a cast of the skull of Heterodontosaurus, the best-known heterodontosaurid from South Africa.

Fossils of these miniature, fanged plant-eaters known as heterodontosaurs, or “different toothed reptiles,” have turned up as far apart as England and China. Now, in a discovery that has been at least 50 years in the making, a new and especially bizarre species of these dwarf herbivores has been identified in a slab of red rock that was collected in the early 1960s by scientists working in South Africa.

In a report published Wednesday in the online journal ZooKeys, Paul C. Sereno, a paleontologist at the University of Chicago and a dinosaur specialist, described the strange anatomy of the newfound member of the heterodontosaur family and gave the new species the name Pegomastax africanus, or “thick jaw from Africa.” He also apologized in an interview for not getting around sooner to this piece of research.

When he first viewed the specimen at a Harvard laboratory, Dr. Sereno said, “my eyes popped, as it was clear this was a distinct species.”

Embedded in the rock were remains of a creature with a short parrotlike beak, one-inch jaws, sharp teeth and a skull no less than three inches long. The entire body was less than two feet in length and probably weighed less than a small house cat.

“I’m embarrassed to say how many years ago that was — 1983,” he said. “But I was an enterprising graduate student then at the American Museum of Natural History. All the while since then, I wondered if anyone else might spot the creature hiding among the lab drawers.”

The Pegomastax fossils were eventually returned to the South African Museum in Cape Town, the true nature of the one slab still undiscovered, Dr. Sereno said. The main researcher responsible for collecting the fossils was Alfred Crompton, a Harvard professor now retired. Part of Dr. Sereno’s research was supported by the National Geographic Society, where he also is an explorer-in-residence.

His close examination showed that behind the parrot-shaped beak were a pair of stabbing canines up front and a set of tall teeth tucked behind for slicing plants. These teeth in upper and lower jaws operated like self-sharpening scissors, Dr. Sereno said, with shearing facets that slid past each other when the jaws closed. The parrotlike skull, he noted, may have been adapted to plucking fruit.

Dr. Sereno said it was “very rare that a plant-eater like Pegomastax would sport sharp-edged enlarged canines.” Some scientists suggested that the creature may have consumed some meat, or at least insects.

In his new study, Dr. Sereno concluded that the creature’s fangs, unusual for a herbivore, were probably “for nipping and defending themselves, not for eating meat.” Other aspects about the new species and other heterodontosaurs, including their chewing mechanism, are evolutionary surprises, he said, and “their anatomy is key to understanding the early evolution of this great group of plant eaters.”

Another possible characteristic of the new species, Dr. Sereno said, is that its body might have been covered in quills, something like those of a porcupine. If so, he pictured that in life Pegomastax would have scampered around in search of suitable plants, looking something like a “nimble two-legged porcupine.”

A version of this article appeared in print on October 4, 2012, on page A4 of the New York edition with the headline: New, Bizarre Species of Small Dinosaur Identified. and article by John Noble Wilford.