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

New study reveals Some animals need extremely little oxygen

February 23rd, 2014

Riffin

One of science’s strongest dogmas is that complex life on Earth could only evolve when oxygen levels in the atmosphere rose to close to modern levels. But now studies of a small sea sponge fished out of a Danish fjord shows that complex life does not need high levels of oxygen in order to live and grow.

The origin of complex life is one of science’s greatest mysteries. How could the first small primitive cells evolve into the diversity of advanced life forms that exists on Earth today? The explanation in all textbooks is: Oxygen. Complex life evolved because the atmospheric levels of oxygen began to rise app. 630 — 635 million years ago.

However new studies of a common sea sponge from Kerteminde Fjord in Denmark shows that this explanation needs to be reconsidered. The sponge studies show that animals can live and grow even with very limited oxygen supplies.

Sea sponge Halichondria panicea was used in the experiment at the University of Southern Denmark.
Credit: Daniel Mills/SDU

In fact animals can live and grow when the atmosphere contains only 0.5 per cent of the oxygen levels in today’s atmosphere.

“Our studies suggest that the origin of animals was not prevented by low oxygen levels,” says Daniel Mills, PhD at the Nordic Center for Earth Evolution at the University of Southern Denmark.

Together with Lewis M. Ward from the California Institute of Technology he is the lead author of a research paper about the work in the journal PNAS.

A little over half a billion years ago, the first forms of complex life — animals — evolved on Earth. Billions of years before that life had only consisted of simple single-celled life forms. The emergence of animals coincided with a significant rise in atmospheric oxygen, and therefore it seemed obvious to link the two events and conclude that the increased oxygen levels had led to the evolution of animals.

“But nobody has ever tested how much oxygen animals need — at least not to my knowledge. Therefore we decided to find out,” says Daniel Mills.

The living animals that most closely resemble the first animals on Earth are sea sponges. The species Halichondria panicea lives only a few meters from the University of Southern Denmark’s Marine Biological Research Centre in Kerteminde, and it was here that Daniel Mills fished out individuals for his research.

“When we placed the sponges in our lab, they continued to breathe and grow even when the oxygen levels reached 0.5 per cent of present day atmospheric levels,” says Daniel Mills.

This is lower than the oxygen levels we thought were necessary for animal life.

The big question now is: If low oxygen levels did not prevent animals from evolving — then what did? Why did life consist of only primitive single-celled bacteria and amoebae for billions of years before everything suddenly exploded and complex life arose?

“There must have been other ecological and evolutionary mechanisms at play. Maybe life remained microbial for so long because it took a while to develop the biological machinery required to construct an animal. Perhaps the ancient Earth lacked animals because complex, many-celled bodies are simply hard to evolve,” says Daniel Mills.

His colleagues from the Nordic Center for Earth Evolution have previously shown that oxygen levels have actually risen dramatically at least one time before complex life evolved. Although plenty of oxygen thus became available it did not lead to the development of complex life.

30 million years old bone-eating worms found

February 21st, 2014

Riffin

An international team of scientists led by the paleontologist Steffen Kiel at the University of Kiel, Germany, found the first fossil boreholes of the worm Osedax that consumes whale bones on the deep-sea floor. They conclude that “boneworms” are at least 30 Million years old.

This result was published in the current issue of the scientific journal Proceedings of the National Academy of Sciences.

Six years ago Osedax was first described based on specimens living on a whale carcass in 2891 m depth off California. Since then paleontologists have been searching for fossil evidence to pin down its geologic age. Now researchers at the Institute of Geosciences at the Christian-Albrechts-University at Kiel, Germany, found 30 Million year old whale bones with holes and excavations matching those of living Osedax in size and shape. The evidence of the boreholes and cavities made by the living worms was provided by Greg Rouse (Scripps Institution of Oceanography), one of the original discoverers of Osedax.

This 30 million year old rib fragment of a whale shows the circular boreholes (diameter: 0,5 mm) made by Osedax.
Credit: Copyright Uni Kiel

To produce accurate images of the fossil boreholes, the bones were CT-scanned by the scientists. The fossil bones belong to ancestors of our modern baleen whales and their age was determined using so-called co-occurring index fossils. “The age of our fossils coincides with the time when whales began to inhabit the open ocean” explains Steffen Kiel, who has been working on the evolution and fossil history of deep-sea ecosystems for many years. Only from the open ocean dead whales could sink to the deep-sea floor where they served as food for the boneworms. “Food is extremely rare on the vast deep-sea floor and the concurrent appearance of these whales and Osedax shows that even hard whale bones were quickly utilized as food source,” Steffen Kiel explains the relevance of their discovery.

The ancient bones were found by the American fossil collector Jim Goedert. He has been collecting fossil along the American Pacific coast for more than 30 years and is well known in the scientific community. Steffen Kiel says: “I got to know Jim when I was a PhD student, when he visited Hamburg University. We kept in touch ever since.” By now, Steffen Kiel has done several field trips with Jim Goedert to the US Pacific coast, a geologically active area where fossil-rich sediments are continuously uplifted by plate tectonic processes.

Vertebrate paleontologists are probably less happy about the old age of Osedax: because it has been feeding on bones for most of the evolutionary history of whales, it is likely to have destroyed many potential whale fossils.

WFS founder Riffin T sajeev Found a large prehistoric Estuary remnants in Indian sub continent

February 20th, 2014

Riffin

Riffin T sajeev Found a lrge prehistoric Estuary remnants

basin may distorts the seismic radiation pattern

February 17th, 2014

Riffin

Tall buildings, bridges and other long-period structures in Greater Vancouver may experience greater shaking from large (M 6.8 +) earthquakes than previously thought due to the amplification of surface waves passing through the Georgia basin, according to two studies published by the Bulletin of the Seismological Society of America (BSSA). The basin will have the greatest impact on ground motion passing over it from earthquakes generated south and southwest of Vancouver.

“For very stiff soils, current building codes don’t include amplification of ground motion,” said lead author Sheri Molnar, a researcher at the University of British Columbia. “While the building codes say there should not be any increase or decrease in ground motion, our results show that there could be an average amplification of up to a factor of three or four in Greater Vancouver.”

The research provides the first detailed studies of 3D earthquake ground motion for a sedimentary basin in Canada. Since no large crustal earthquakes have occurred in the area since the installation of a local seismic network, these studies offer refined predictions of ground motion from large crustal earthquakes likely to occur.

Southwestern British Columbia is situated above the seismically active Cascadia subduction zone. A complex tectonic region, earthquakes occur in three zones: the thrust fault interface between the Juan de Fuca plate, which is sliding beneath the North America plate; within the over-riding North America plate; and within the subducting Juan de Fuca plate.

Molnar and her colleagues investigate the effect the three dimensional (3D) deep basin beneath Greater Vancouver has on the earthquake-generated waves that pass through it. The Georgia basin is one in a series of basins spanning form California to southern Alaska along the Pacific margin of the North America and is relatively wide and shallow. The basin is filled with sedimentary layers of silts, sands and glacial deposits.

While previous research suggested how approximately 100 meters of material near the surface would affect ground shaking, no studies had looked at the effect of the 3D basin structure on long period seismic waves.

To fill in that gap in knowledge, Molnar and colleagues performed numerical modeling of wave propagation, using various scenarios for both shallow quakes (5 km in depth) within the North America plate and deep quakes (40 — 55 km in depth) within the Juan de Fuca subducting plate, the latter being the most common type of earthquake. The authors did not focus on earthquakes generated by a megathrust rupture of the Cascadia subduction zone, a scenario studied previously by co-author Kim Olsen of San Diego State University.

For these two studies, the authors modeled 10 scenario earthquakes for the subducting plate and 8 shallow crustal earthquakes within the North America plate, assuming rupture sites based on known seismicity. The computational analyses suggest the basin distorts the seismic radiation pattern — how the energy moves through the basin — and produces a larger area of higher ground motions. Steep basin edges excite the seismic waves, amplifying the ground motion.

Multiple scenarios for earthquakes within the Georgia Basin underneath Vancouver indicate that earthquakes would be amplified.
Credit: Sheri Molnar and Kim Olsen

The largest surface waves generated across Greater Vancouver are associated with earthquakes located approximately 80 km or more, south-southwest of the city, suggest the authors.

“The results were an eye opener,” said Molnar. “Because of the 3D basin structure, there’s greater hazard since it will amplify ground shaking. Now we have a grasp of how much the basin increases ground shaking for the most likely future large earthquakes.”

In Greater Vancouver, there are more than 700 12-story and taller commercial and residential buildings, and large structures — high-rise buildings, bridges and pipelines — that are more affected by long period seismic waves, or long wavelength shaking. “That’s where these results have impact,” said Molnar.

Connection between color and physiology of dinosaurs revealed

February 16th, 2014

Riffin

New research that revises the rules allowing scientists to decipher color in dinosaurs may also provide a tool for understanding the evolutionary emergence of flight and changes in dinosaur physiology prior to its origin.

In a survey comparing the hair, skin, fuzz and feathers of living terrestrial vertebrates and fossil specimens, a research team from The University of Texas at Austin, the University of Akron, the China University of Geosciences and four other Chinese institutions found evidence for evolutionary shifts in the rules that govern the relationship between color and the shape of pigment-containing organelles known as melanosomes, as reported in the Feb. 13 edition of Nature.

At the same time, the team unexpectedly discovered that ancient maniraptoran dinosaurs, paravians, and living mammals and birds uniquely shared the evolutionary development of diverse melanosome shapes and sizes. (Diversity in the shape and size of melanosomes allows scientists to decipher color.) The evolution of diverse melanosomes in these organisms raises the possibility that melanosome shape and size could yield insights into dinosaur physiology.

Melanosomes have been at the center of recent research that has led scientists to suggest the colors of ancient fossil specimens covered in fuzz or feathers.

Melanosomes contain melanin, the most common light-absorbing pigment found in animals. Examining the shape of melanosomes from fossil specimens, scientists have recently suggested the color of several ancient species, including the fuzzy first-discovered feathered dinosaur Sinosauropteryx, and feathered species like Microraptor and Anchiornis.

According to the new research, color-decoding works well for some species, but the color of others may be trickier than thought to reconstruct.

The “rules” allowing color reconstruction from the shape of melanin-containing organelles originate with feathered dinosaurs, and are associated with an increase in melanosome diversity. However, fuzzy dinosaurs like T. rex and Sinosauropteryx show a pattern found in other amniotes like lizards and crocodilians in which a limited diversity of shapes doesn’t allow color reconstruction. An explosion in the distribution of the shapes of melanin-containing organelles preserved in living taxa and the fossil record may point to a key physiological shift within feathered dinosaurs.
Credit: Li et al. (authors).

Comparing melanosomes of 181 extant specimens, 13 fossil specimens and all previously published data on melanosome diversity, the researchers found that living turtles, lizards and crocodiles, which are ectothermic (commonly known as cold-blooded), show much less diversity in the shape of melanosomes than birds and mammals, which are endothermic (warm-blooded, with higher metabolic rates).The limited diversity in melanosome shape among living ectotherms shows little correlation to color. The same holds true for fossil archosaur specimens with fuzzy coverings scientists have described as “protofeathers” or “pycnofibers.” In these specimens, melanosome shape is restricted to spherical forms like those in modern reptiles, throwing doubt on the ability to decipher the color of these specimens from fossil melanosomes.

In contrast, in the dinosaur lineage leading to birds, the researchers found an explosion in the diversity of melanosome shape and size that appears to correlate to an explosion of color within these groups. The shift in diversity took place abruptly, near the origin of pinnate feathers in maniraptoran dinosaurs.

“This points to a profound change at a pretty discrete point,” says author Julia Clarke of The University of Texas at Austin’s Jackson School of Geosciences. “We’re seeing an explosion of melanosome diversity right before the origin of flight associated with the origin of feathers.”

What surprised the researchers was a similarity in the pattern of melanosome diversity among ancient maniraptoran dinosaurs, paravians, and living mammals and birds.

“Only in living, warm-blooded vertebrates that independently evolved higher metabolic rates do we see the melanosome diversity we also see in feathered dinosaurs,” said co-author Matthew Shawkey of The University of Akron.

Many of the genes involved in the melanin color system are also involved in other core processes such as food intake, the stress axis, and reproductive behaviors. Because of this, note the researchers, it is possible that the evolution of diverse melanosome shapes is linked to larger changes in energetics and physiology.

Melanosome shape could end up offering a new tool for studying endothermy in fossil specimens, a notoriously challenging subject for paleontologists.

Because the explosion of diversity in melanosomes appears to have taken place right at the origin of pinnate feathers, the change may indicate that a key shift in dinosaurian physiology occurred prior to the origin of flight.

“We are far from understanding the exact nature of the shift that may have occurred,” says Clarke. “But if changes in genes involved in both coloration and other aspects of physiology explain the pattern we see, these precede flight and arise close to the origin of feathers.”

It is possible, notes Clarke, that a diversity in melanosome shape (and correlated color changes) resulted from an increased evolutionary role for signaling and sexual selection that had a carryover effect on physiology, or that a change in physiology closely preceded changes in color patterning. At this point, she stresses, both ideas are speculative.

“What is interesting is that trying to get at color in extinct animals may have just started to give us some insights into changes in the physiology of dinosaurs.”

Jaw dropping: Scientists reveal how vertebrates came to have a face

February 14th, 2014

Riffin

A team of French and Swedish researchers have presented new fossil evidence for the origin of one of the most important and emotionally significant parts of our anatomy: the face. Using micron resolution X-ray imaging, they show how a series of fossils, with a 410 million year old armoured fish called Romundina at its centre, documents the step-by-step assembly of the face during the evolutionary transition from jawless to jawed vertebrates.

The research is published in Nature on 12 February 2014.

Vertebrates, or backboned animals, come in two basic models: jawless and jawed. Today, the only jawless vertebrates are lampreys and hagfishes, whereas jawed vertebrates number more than fifty thousand species, including ourselves. It is known that jawed vertebrates evolved from jawless ones, a dramatic anatomical transformation that effectively turned the face inside out.

This image shows a reconstruction in three dimensions of the skull of the small fossil fish Romundina (415 million years old) that was scanned at the ESRF. The internal structures of the face reveal the internal anatomy show a mixture of structures of jawless and jawed vertebrates (in anterior view). External bones of two different kinds in orange and pink grey, nerves and cranial cavity in yellow, arteries in red, veins in dark blue and inner ears in light blue; anterior part of the bone rendered semitransparent.
Credit: Vincent Dupret, Uppsala University

In embryos of jawless vertebrates, blocks of tissue grow forward on either side of the brain, meeting in the midline at the front to create a big upper lip surrounding a single midline “nostril” that lies just in front of the eyes. In jawed vertebrates, this same tissue grows forward in the midline under the brain, pushing between the left and right nasal sacs which open separately to the outside. This is why our face has two nostrils rather than a single big hole in the middle. The front part of the brain is also much longer in jawed vertebrates, with the result that our nose is positioned at the front of the face rather than far back between our eyes.

Until now, very little has been known about the intermediate steps of this strange transformation. The scientists studied the skull of Romundina, an early armoured fish with jaws, or placoderm, from arctic Canada. The skull is part of a collection of the French National Natural History Museum in Paris.

Romundina has separate left and right nostrils, but they sit far back, behind an upper lip like that of a jawless vertebrate. “This skull is a mix of primitive and modern features, making it an invaluable intermediate fossil between jawless and jawed vertebrates,” says Vincent Dupret of Uppsala University, one of two lead authors of the study.

By imaging the internal structure of the skull using high-energy X-rays at the European Synchrotron (ESRF) in Grenoble, France, the authors show that the skull housed a brain with a short front end, very similar to that of a jawless vertebrate.

“In effect, Romundina has the construction of a jawed vertebrate but the proportions of a jawless one,” says Per Ahlberg, of Uppsala University and the other lead author of the study. “This shows us that the organization of the major tissue blocks was the first thing to change, and that the shape of the head caught up afterwards,” he adds.

By placing Romundina in a sequence of other fossil fishes, some more primitive and some more advanced, the authors were able to map out all the main steps of the transition.

“Without the intense X-rays produced at the ESRF, we would not have been able to create a virtual representation of the internal structures of the skull” said Sophie Sanchez from The European Synchrotron (ESRF) in Grenoble.

Terrestrial Origin of Viviparity in Mesozoic Marine Reptiles Indicated by Early Triassic Embryonic Fossils

February 13th, 2014

Riffin

Viviparity in Mesozoic marine reptiles has traditionally been considered an aquatic adaptation. We report a new fossil specimen that strongly contradicts this traditional interpretation. The new specimen contains the oldest fossil embryos of Mesozoic marine reptile that are about 10 million years older than previous such records. The fossil belongs to Chaohusaurus (Reptilia, Ichthyopterygia), which is the oldest of Mesozoic marine reptiles (ca. 248 million years ago, Early Triassic). This exceptional specimen captures an articulated embryo in birth position, with its skull just emerged from the maternal pelvis. Its headfirst birth posture, which is unlikely to be a breech condition, strongly indicates a terrestrial origin of viviparity, in contrast to the traditional view. The tail-first birth posture in derived ichthyopterygians, convergent with the conditions in whales and sea cows, therefore is a secondary feature. The unequivocally marine origin of viviparity is so far not known among amniotes, a subset of vertebrate animals comprising mammals and reptiles, including birds. Therefore, obligate marine amniotes appear to have evolved almost exclusively from viviparous land ancestors. Viviparous land reptiles most likely appeared much earlier than currently thought, at least as early as the recovery phase from the end-Permian mass extinction.

The maternal specimen with three embryos.
Color coding indicates: black, maternal vertebral column, including neural and haemal spines; blue, maternal pelvis and hind flipper; green, maternal ribs and gastralia. Embryos 1 and 2 are in orange and yellow, respectively, whereas neonate 1 is in red. Scale bar is 1 cm. Abbreviations: i-v, metatarsals; 4, fourth distal tarsal; a, astragalus; c, calcaneum; cr, caudal rib; cv, caudal vertebra; d, dentary; fe, femur; fi, fibula; h, haemal spine; il, ilium; is, ischium; pb, pubis; pm, premaxilla; sr, sacral rib; sv, sacral vertebra; and ti, tibia. See fig. S2 for a high resolution image.
doi:10.1371/journal.pone.0088640.g002

Completeness of the two skeletons used in maternal body size estimation.
(A), AGM CHS-5, a nearly complete skeleton that is almost as large as AGM I-1. (B), AGM CH-628-22, a complete skeleton that preserves the tail tip. Large scale bars are 10 cm, and short bars 2 cm.
doi:10.1371/journal.pone.0088640.g003

Stylized reconstruction of adult and embryo of Chaohusaurus in comparison to a derived ichthyopterygian.
(A), adult based on AGM I-1 and CHS-5. Rectangle indicates the approximate range preserved in AGM I-1. Colored silhouettes of embryo are placed in approximate positions of embryos 1 and 2, with embryo 3 displaced to avoid overlap with embryo 2. The extent of the maternal tail tip, in gray, is based on AGM-CH-628-22. Scleral ring is based on AGM-CHS-3. (B), embryo based on embryo 2 and neonate 1 of AGM I-1. Elements in gray are missing. (C), the derived ichthyopterygian Stenopterygius with one embryo in birth position and three in body cavity, reconstructed based on SMNS 6293 (Staatliches Museum für Naturkunde, Stüttgart, Germany). Scale bars are 5 cm. See fig. S3 for a high resolution image.
doi:10.1371/journal.pone.0088640.g004

Citation: Motani R, Jiang D-y, Tintori A, Rieppel O, Chen G-b (2014) Terrestrial Origin of Viviparity in Mesozoic Marine Reptiles Indicated by Early Triassic Embryonic Fossils. PLoS ONE 9(2): e88640. doi:10.1371/journal.pone.0088640

Editor: Peter Dodson, University of Pennsylvania, United States of America

CALGARY – A new fossil site in Canada

February 11th, 2014

Riffin

CALGARY – A new fossil site discovered in Kootenay National Park may be one of the world’s most important, according to researchers. A century after the discovery of Yoho National Park’s 505 million-year-old Burgess Shale, officials say a new fossil site has been located just 42 kilometres away. The new Marble Canyon fossil bed was found by an expedition team from the Royal Ontario Museum who made the trek to the Canadian Rockies. It was actually a hunch that led the expedition team to the area of Marble Canyon, where they discovered a startling variety of fossils. They pinpointed the source of the fossils to higher up on the mountain slopes and began to excavate the fossils layer-by-layer. In a little over two weeks, the researchers collected thousands of specimens representing more than 50 animal species, several of which were new to science. Researchers say it could turn out to be one of the most important discoveries of this generation.

The new Marble Canyon fossil bed was found by an expedition team from the Royal Ontario Museum who made the trek to the Canadian Rockies.

“This new discovery is an epic sequel to a research story that began at the turn of the previous century,” says Dr. Jean-Bernard Caron, Curator of Invertebrate Paleontology at the Royal Ontario Museum. “There is no doubt in my mind that this new material will significantly increase our understanding of early animal evolution.”

The new fossil site is protected by Parks Canada, who says the exact location will remain confidential to protect its integrity.

However, there may be an opportunity for guided hikes through the area in the future.

This latest discovery, made in the summer of 2012, is described in the latest edition of the prestigious science journal Nature Communication, released on Tuesday.

Officials say it will help scientists further understand the sudden explosion of animal life during the Cambrian period.

Is there an ocean beneath our feet? Ocean water may reach upper mantle through deep sea faults

February 10th, 2014

Riffin

Scientists at the University of Liverpool have shown that deep sea fault zones could transport much larger amounts of water from Earth’s oceans to the upper mantle than previously thought.

Water is carried mantle by deep sea fault zones which penetrate the oceanic plate as it bends into the subduction zone. Subduction, where an oceanic tectonic plate is forced beneath another plate, causes large earthquakes such as the recent Tohoku earthquake, as well as many earthquakes that occur hundreds of kilometers below Earth’s surface.

Parinacota, a volcano on the border of Chile and Bolivia. Credit: © Georges Bartoccioni / Fotolia

Seismic modelling

Seismologists at Liverpool have estimated that over the age of Earth, the Japan subduction zone alone could transport the equivalent of up to three and a half times the water of all Earth’s oceans to its mantle.

Using seismic modelling techniques the researchers analysed earthquakes which occurred more than 100 km below Earth’s surface in the Wadati-Benioff zone, a plane of Earthquakes that occur in the oceanic plate as it sinks deep into the mantle.

Analysis of the seismic waves from these earthquakes shows that they occurred on 1 — 2 km wide fault zones with low seismic velocities. Seismic waves travel slower in these fault zones than in the rest of the subducting plate because the sea water that percolated through the faults reacted with the oceanic rocks to form serpentinite — a mineral that contains water.

Some of the water carried to the mantle by these hydrated fault zones is released as the tectonic plate heats up. This water causes the mantle material to melt, causing volcanoes above the subduction zone such as those that form the Pacific ‘ring of fire’. Some water is transported deeper into the mantle, and is stored in the deep Earth.

“It has been known for a long time that subducting plates carry oceanic water to the mantle,” said Tom Garth, a PhD student in the Earthquake Seismology research group led by Professor Andreas Rietbrock.

“This water causes melting in the mantle, which leads to arc releasing some of the water back into the atmosphere. Part of the subducted water however is carried deeper into the mantle and may be stored there.

Large amounts of water deep in Earth

“We found that fault zones that form in the deep oceanic trench offshore Northern Japan persist to depths of up to 150 km. These hydrated fault zones can carry large amounts of water, suggesting that subduction zones carry much more water from the ocean down to the mantle than has previously been suggested.

“This supports the theory that there are large amounts of water stored deep in the Earth.”

Understanding how much water is delivered to the mantle contributes to knowledge of how the mantle convects, and how it melts, which helps to understand how plate tectonics began, and how the continental crust was formed.

Courtesy:University of Liverpool. “Is there an ocean beneath our feet? Ocean water may reach upper mantle through deep sea faults.” ScienceDaily. ScienceDaily, 27 January 2014. <www.sciencedaily.com/releases/2014/01/140127093207.htm>.

‘Steak-knife’ teeth reveal ecology of oldest land predators

February 7th, 2014

Riffin

Source: University of Toronto

The first top predators to walk on land were not afraid to bite off more than they could chew, a University of Toronto Mississauga study has found.

Graduate student and lead author Kirstin Brink along with Professor Robert Reisz from U of T Mississauga’s Department of Biology suggest that Dimetrodon, a carnivore that walked on land between 298 million and 272 million years ago, was the first terrestrial vertebrate to develop serrated ziphodont teeth.

This is a Dimetrodon skull with histological thin section tooth detail by Danielle Dufault.
Credit: Danielle Dufault

According to the study published in Nature Communications, ziphodont teeth, with their serrated edges, produced a more-efficient bite and would have allowed Dimetrodon to eat prey much larger than itself.

While most meat-eating dinosaurs possessed ziphodont teeth, fossil evidence suggests serrated teeth first evolved in Dimetrodon some 40 million years earlier than theropod dinosaurs.

“Technologies such as scanning electron microscope (SEM) and histology allowed us to examine these teeth in detail to reveal previously unknown patterns in the evolutionary history of Dimetrodon,” Brink said.

The four-meter-long Dimetrodon was the top of the terrestrial food chain in the Early Permian Period and is considered to be the forerunner of mammals.

According to Brink and Reisz’s research, Dimetrodon had a diversity of previously unknown tooth structures and were also the first terrestrial vertebrate to develop cusps — teeth with raised points on the crown, which are dominant in mammals.

The study also suggests ziphodont teeth were confined to later species of Dimetrodon, indicating a gradual change in feeding habits.

“This research is an important step in reconstructing the structure of ancient complex communities,” Reisz said.

“Teeth tell us a lot more about the ecology of animals than just looking at the skeleton.”

“We already know from fossil evidence which animals existed at that time but now with this type of research we are starting to piece together how the members of these communities interacted.”

Brink and Reisz studied the changes in Dimetrodon teeth across 25 million years of evolution.

The analysis indicated the changes in tooth structure occurred in the absence of any significant evolution in skull morphology. This, Brink and Reisz suggest, indicates a change in feeding style and trophic interactions.

“The steak knife configuration of these teeth and the architecture of the skull suggest Dimetrodon was able to grab and rip and dismember large prey,” Reisz said.

“Teeth fossils have attracted a lot of attention in dinosaurs but much less is known about the animals that lived during this first chapter in terrestrial evolution.”