Category: Dinosaur and Prehistoric Animal News Stories

Trilobite Reproduction Puzzle Solved

Trilobite Eggs Found in Ordovican Fossil

Trilobites are some of the most recognisable fossils to be found in Palaeozoic strata.  However, despite there being tens of thousands of exceptionally preserved specimens, little is known about how Trilobites bred.  Trilobite reproduction has remained a bit of a mystery.  A team of scientists from Western Illinois University in collaboration with colleagues from Vanderbilt University (Nashville, Tennessee), writing in the academic journal “Geology” have published a paper on a remarkable fossil find.  They report finding the first evidence of Trilobite eggs preserved within a fossil specimen.

A Trilobite Fossil

A fossil of an Trilobite.

A beautiful Trilobite fossil.

The Trilobita

Trilobites are an extinct, geographically widespread and abundant group of Palaeozoic arthropods that evolved in the Cambrian and survived until the Permian mass extinction event some 252 million years ago.  Trilobites have a distinctive threefold longitudinal division of the body and a tough exoskeleton.  At least ten Orders of Trilobita have been assigned and although most Trilobites were small, the largest specimens grew to up to a metre in length.  All Trilobites lived in marine environments and they evolved to occupy a number of ecological niches from active, predatory nektonic animals to epifaunal forms.  In order to grow, these animals had to moult and shed their exoskeleton.  The cast exoskeleton readily fossilised and as a result, huge numbers of Trilobite fossil material is present.

An analysis of an exceptionally well-preserved specimen of the Late Ordovican Trilobite (Triarthrus eatoni) from the Lorraine Group found in the United States has revealed the presence of nine tiny eggs, clustered together in an area located underneath the head shield (the genal area of the cephalon).  Other specimens also show evidence of eggs within the fossilised form.

Digital Images from the Computerised Tomography Showing the Tiny Eggs

Trilobite eggs.

A digital reconstruction of T. eatoni shows evidence of Trilobite egg formation.

Picture Credit: Geological Society of America

The image above shows close up views of the cephalon and the upper portion of the trunk.  Picture K represents a dorsal view (view from the top), picture L (ventral view), viewed from underneath and picture M is a left ventral view.  The egg cluster, represented by the tiny white dots can be clearly seen.

Spherical and Elliptical Eggs

Like many fossil Trilobite specimens from the Lorraine Group, the complete exoskeleton has been replaced with pyrite.  The eggs are described as being spherical to elliptical in shape, although the fossilisation process could have distorted the material.  Each egg is approximately 200 μm in size, that’s around half the width of a human hair.  The eggs are only visible ventrally with no dorsal brood pouch or recognised sexual dimorphism.

Triathrus eatoni (Ordovician Whetstone Gulf Formation) Reveals Eggs

Fossil eggs in Trilobite fossil discovered.

Pyritised specimens of Triarthrus eatoni showing evidence of fossil eggs.

Picture Credit: Geological Society of America

The picture above show a pyritised specimen of T. eatoni, part of the collection of the Yale Peabody Museum showing nine eggs (picture A is ventral view).  Picture B shows a second specimen with four eggs preserved in the right genal area.  Picture C is a close up of the eggs in specimen B, whilst D is a closer view of the eggs preserved in specimen A.

Highly magnified (scanning electron microscopy), views of an egg cluster (E) with a closer view of a single egg (F).  Picture G shows the egg surface under high magnification.

A close up of a single limb from specimen A is shown in picture H, whilst images I and J show pyritised elements of the body fossil.

Reproduction Strategy Similar to Modern Horseshoe Crabs

The location of the eggs is consistent with where extant female horseshoe crabs release their unfertilised eggs from the ovarian network within their head.  Trilobites probably released their gametes (eggs and sperm) through a genital pore of as-yet unknown location (likely near the posterior boundary of the head).  If the T. eatoni reproductive biology is representative of other trilobites, they spawned with external fertilisation, possibly the ancestral mode of reproduction for early members of the Arthropoda.  As pyritisation preferentially preserves the external rather than internal features of fossils, it is suggested that there is likely a bias in the fossil record toward the preservation of Arthropods that brood eggs externally, animals with an exoskeleton that brood their eggs internally are unlikely to preserve any evidence of their mode of reproduction.

The scientific paper: “Pyritised in situ Trilobite Eggs from the Ordovician of New York (Lorraine Group): Implications for Trilobite Reproductive Biology” published in Geology.

Hyoliths Find a Home

Ancient, Long Extinct Animal Finds Place on Tree of Life

A bizarre shelled marine creature’s place in the Animal Kingdom has finally been resolved thanks to the efforts of a remarkable student at the University of Toronto.  Undergraduate student Joseph Moysiuk has identified Hyoliths, not as members of the Mollusca, which many palaeontologists had previously believed, but as lophophores and as such, they are closely related to brachiopods.

An Illustration of the Hyolith Haplophrentis

The Hyolith Haplophrentis.

An illustration of the Hyolith Haplophrentis.

Picture Credit: Royal Ontario Museum/Danielle Dufault

In the Hyolith illustration above, a tiny brachiopod can be seen attached to the nearest appendage of Haplophrentis.

The distinctive appearance and structure of the Hyolith skeleton has obstructed previous attempts to classify these animals.  All Hyoliths had an elongated, bilaterally symmetrical cone-shaped shell and a smaller cap-like shell that covered the opening of the conical shell (known as an operculum).  Some species also bore a pair of rigid, curved spines (helens) that protruded from between the conical shell and operculum (the shell cap), structures with no equivalents in any other group of animals.

Extensive Fossil Record

The mineralised external skeletons (argonite) and their sessile/semi-sessile habit (living on the seabed), gives these animals, which range in size from 1 cm to around 5 cm in length, a good fossil preservation potential.  The earliest fossil evidence for this type of creature occurs in rocks dating from around 540 million years ago (Cambrian).  These filter feeders seem to have persisted throughout the Palaeozoic and the Hyolith fossil record is relatively abundant and geographically widespread.  The Hyolitha were very diverse during the Cambrian and the subsequent Ordovician geological period, before their fossil record and their presence as an important member of marine benthos communities (animals and plants living on the sea floor) declines.  Hyoliths are one of many types of marine invertebrate that failed to survive into the Mesozoic.

The Cambrian Hyolith Haplophrentis

Burgess Shale Hyolith fossil.

Soft tissue of a Cambrian Hyolith (Haplophrentis) has been preserved.

Picture Credit:  Royal Ontario Museum

In the picture of a Hyolith fossil above, (genus Haplophrentis – H. carinatus), the conical shape of the shell can be clearly made out and the partially extended lophophore (feeding organ) can be seen.  The lophophore consisting of numerous, blackened, thin, finger-like extensions is highlighted against the operculum.  The curved spines are the helens.

Writing in the academic journal “Nature”, student Joseph Moysiuk and his fellow authors, Durham University’s Martin Smith and Burgess Shale fossil expert Jean-Bernard Caron, studied over 1,500 fossil specimens from the mid-Cambrian strata that represent elements of the Burgess Shale (British Columbia) and the Spence Shale Formations (Idaho and Utah).  The Hyolith material (Haplophrentis) and its exceptional state of preservation permitted the team to assess the soft tissue structures and from this information the team were able to deduce their taxonomic affinities.

Dr Caron explained:

“Burgess Shale fossils are exceptional because they show preservation of soft tissues which are not usually preserved in normal conditions.”

Not Closely Related to Snails, Cephalopods and Other Molluscs

The analysis showed that Hyoliths are not closely related to snails, squid or other members of the Mollusca.  They are instead, more closely related to the Brachiopoda, a group of animals with a rich fossil record but with few extant representatives.  Brachiopods have a soft body enclosed between upper and lower shells (valves), unlike the left and right arrangement of valves in bivalve molluscs.  Brachiopods open their valves at the front when feeding but otherwise keep them closed to protect their feeding apparatus and other body parts.

Student Moysiuk commented:

“Our most important and surprising discovery is the Hyolith feeding structure, which is a row of flexible tentacles extending away from the mouth, contained within the cavity between the lower conical shell and upper cap-like shell.  Only one group of living animals – the brachiopods, has a comparable feeding structure enclosed by a pair of valves.  This finding demonstrates that brachiopods, and not molluscs, are the closest surviving relatives of Hyoliths.”

The undergraduate added:

“It suggests that these Hyoliths fed on organic material suspended in water as living brachiopods do today, sweeping food into their mouths with their tentacles,”

A Diagram Showing the Proposed Anatomy of a Hyolith

Haplophrentis anatomy.

Diagrams showing the anatomy of the Cambrian Hyolith Haplophrentis.

Picture Credit: Royal Ontario Museum/Danielle Dufault

The Function of the Helens

Examination of the orientation of the helens in multiple Hyolith specimens from the Burgess Shale suggests that these spines may have been used like stilts to lift the body of the animal above the sediment, elevating the feeding apparatus to enhance feeding.

Dr Caron led recent field exhibitions to the Burgess Shale.  This resulted in the discovery of many specimens that form the basis of this research.  The key specimens came from recently discovered deposits near Stanley Glacier and Marble Canyon in Kootenay National Park, about twenty miles south-east of the original Burgess Shale site in Yoho National Park.

Exploring the Burgess Shale

Exploring the Burgess Shales.

Student Joseph Moysiuk (left) in the field with Dr Jean-Bernard Caron.

Picture Credit: Joseph Moysiuk

Palaeontology lecturer Martin Smith expressed his delight at being able to help solve a 175-year-old palaeontological puzzle.  Hyolith fossils have been included in a number of fossil studies previously, but until now, where these creatures featured in the tree of life remained open to speculation.

Dr Smith stated:

“Resolving the debate over the Hyoliths adds to our understanding of the Cambrian Explosion, the period of rapid evolutionary development when most major animal groups emerge in the fossil record.  Our study reiterates the importance of soft tissue preservation from Burgess Shale-type deposits in illuminating the evolutionary history of creatures about which we still know very little.”

Everything Dinosaur acknowledges the assistance of the University of Toronto in the compilation of this article.

Tomato and Potato Ancestors Found in Eocene Rocks

Fossil Fruit Reveal the Ancient Ancestry of the Nightshade Family of Flowering Plants

Scientists working in a remote part of Chubut Province, Argentina, have found evidence of the ancient berries of a member of the nightshade family (Solanaceae).  Today, some 2,500 species of this diverse plant family are known, many of these plants are economically important (tomatoes, peppers, potatoes, tobacco and petunias).  The complex chemical compounds several species produce, have proved to be invaluable to medical research, but until now, molecular data from extant species suggested that these types of flowering plants evolved some ten million years ago.

The Fossil Species Has Been Named Physalis infinemundi

Physalis infinemundi.

The papery husk can be clearly seen on this specimen of Physalis infinemundi.

Picture Credit: Ignacio Escapa / Museo Paleontológico Egidio Feruglio

Writing in the journal “Science”, researchers including Professor Peter Wilf (Pennsylvania State University), have identified the fossilised delicate, lantern-like husks of a type of a type of Physalis, complete with impressions of the plant’s fruit, completely turned to carbon due to the fossilisation process.

The strata in which the two fossil lantern fruit specimens were found has been dated using palaeomagnetism and volcanic ash deposits.  These rock layers were deposited some 52 million-years-ago.  The Physalis genus contains ground cherries and husk tomatoes as well as tomatillos, a staple of Mexican cuisine.  The entire family, like many plant families has a very sparse fossil record, however, all that changed when a team of international scientists explored the Eocene deposits at Laguna del Hunco, (Chubut Province, Patagonia, Argentina), a location where the fossils of a temperate rainforest have been preserved.  More than six thousand fossil specimens have been excavated and the site has been the focus of a Pennsylvania State University, Museo Palentologico Egidio Feruglio, Trelew, Argentina, and Cornell University (New York), project for more than a decade.

The Remote Laguna del Hunco Location

Exploring an Eocene temperate rainforest.

The remote Laguna del Hunco, (Chubut Province), fossil site.

Picture Credit: Peter Wilf/Pennsylvania State University with additional annotation by Everything Dinosaur

The red arrow in the picture points to a group of researchers looking for fossils.

Southern Gondwana

Around 52 million-years-ago, a substantial temperate rainforest covered this part of the remnants of the giant, southern, super-continent Gondwana.  Although, the climate was warmer than today, the ecosystem would have superficially resembled those fragments of forests found in the Lake District, the West Country, parts of Wales and western Scotland, where Atlantic winds bring huge amounts of rain to woodlands.

Commenting on the exceptionally rare fossil discovery, Peter Wilf (Professor of Geosciences, Pennsylvania State University) stated:

“These astonishing, extremely rare specimens of Physalis fruits are the only two fossils known of the entire nightshade family that preserve enough information to be assigned to a genus within the family.  We exhaustively analysed every detail of these fossils in comparison with all potential living relatives and there is no question that they represent the world’s first Physalis fossils and the first fossil fruits of the nightshade family.  Physalis sits near the tips of the nightshade family’s evolutionary tree, meaning that the nightshades as a whole, contrary to what was thought, are far older than 52 million years.”

 

Fossil Indicates that the Solanaceae Are a Very Ancient Plant Family

Ancient nighshade fossil.

Physalis infinemundi fossil. In this specimen, the former papery and lobed husk is broken at top to reveal the large, fleshy berry underneath

Picture Credit: Peter Wilf/Pennsylvania State University

Mónica Carvalho, a former student at Pennsylvania State University and a co-author of the scientific paper explained:

These fossils are one of a kind, since the delicate papery covers of lantern fruits are rarely preserved as fossils.  Our fossils show that the evolutionary history of this plant family is much older than previously considered, particularly in South America, and they unveil important implications for understanding the diversification of the family.

All extant members of the Physalis genus are found in the New World and the research team notes that the Physalis fossils show a rare link from ancient Patagonia, to living Physalis plants of the Americas.  However, most other fossil plants such as Eucalyptus, found at Laguna del Hunco have living relatives concentrated in Australasia.  This distribution pattern reflects the geographical connection between South America, Antarctica and Australia.  This new study raises the intriguing possibility that more, potentially older Solanaceae fossils might be discovered at more southerly latitudes.

The researchers conclude that their results reinforce the emerging pattern wherein numerous fossil plant taxa from southern Argentina and Antarctica are substantially older than their dates of origin derived from molecular research.

Everything Dinosaur acknowledges the contribution of Pennsylvania State University in the compilation of this article.

Dinosaur Embryo Study Hints at Extinction Theory

How Long Did Dinosaur Eggs Take to Hatch?

Dinosaurs laid eggs, that’s the consensus view in palaeontology, no evidence has been found to date of viviparity for example, but how long did it take for a dinosaur egg to hatch?  That question has been answered to some extent thanks to some fascinating research conducted by scientists at Florida State University working in collaboration with colleagues at Calgary University (Alberta, Canada) and the American Museum of Natural History (New York).   This study might shed light on why the Dinosauria were unable to recover from the climate catastrophe that marked the Cretaceous/Palaeogene (K-Pg) extinction event.

The Teeth of Protoceratops Embryos were Included in the Study

A baby Protoceratops skeleton.

The fossilised remains of a young Protoceratops.

Picture Credit: Gregory Erickson (Florida State University)

The researchers examined the embryonic teeth of dinosaurs, preserved entombed in fossilised eggs.  In some extant animals, as the embryo grows, so the teeth record daily growth rates.  Lines observed on an embryonic tooth can be used to determine how quickly the embryo was growing and therefore, by implication, how long it took the dinosaur to hatch.

Two Different Dinosaurs Studied

Writing in the Proceedings of the National Academy of Science, the researchers calculate that in the two types of dinosaur they studied (Protoceratops and the hadrosaurid Hypacrosaurus), eggs took between three and six months to hatch.

Commenting on the study, lead author Professor Gregory Erickson (Florida State University) stated:

“Some of the greatest riddles about dinosaurs pertain to their embryology, virtually nothing is known.  Did their eggs incubate slowly like their reptilian cousins, crocodilians and lizards?  Or rapidly like living dinosaurs, the birds?”

The Enormous Late Cretaceous Hadrosaur Hypacrosaurus was Included in the Study

Two Duck-billed dinosaurs (Hypacrosaurus).

Hypacrosaurus embryos were studied.

Picture Credit: Ohio State University

Fossils of embryonic dinosaurs are extremely rare.  Few specimens have been found, however, there are exceptions.  For example, a number of Protoceratops nests have been excavated from Upper Cretaceous deposits in Mongolia, whilst extensive bone beds of Hypacrosaurus have been discovered, including several nesting sites in Alberta and northern Montana (United States).  Hypacrosaurus specimens represent a range of ages, from embryos through to fully mature individuals.  As a result, this genus has been extensively studied in a bid to discover the growth rates of dinosaurs.  It has been discovered that these duck-billed dinosaurs grew very rapidly once hatched, reaching maturity after about two to three years.  Hypacrosaurus grew much faster than the predatory tyrannosaurids, with which it co-existed.

To read more about the study of Hypacrosaurus growth rates: Duck-billed Dinosaurs Grew Up Fast to Avoid Getting Eaten

Studying Dinosaur Embryos

Palaeontologists have postulated that dinosaur egg incubation was similar to that of modern birds.  Birds eggs hatch in time intervals ranging from eleven to eighty-five days.  Comparable-sized reptilian eggs such as crocodiles, caiman and lizards typically take twice as long to hatch.  The American Alligator (Alligator mississippiensis), North America’s largest living reptile, lays an egg around nine centimetres in length that takes between 62 to 68 days to hatch.  Komodo Dragon (Varanus komodoensis) eggs, can take much longer, between seven to eight months to incubate.

As some dinosaur eggs can be very large, the eggs of Hypacrosaurus are estimated to have weighed around four kilogrammes and were about the size of a volleyball, scientists believed that the embryonic dinosaurs would have incubated rapidly, a characteristic inherited by the dinosaur’s near relatives, the birds.

Professor Erickson with Florida State University graduate David Kay and collaborators from the American Museum of Natural History and the University of Calgary, decided to test this hypothesis.

Co-author of the paper, Darla Zelenitsky (Assistant Professor of Geoscience at the University of Calgary) explained:

“Time within the egg is a crucial part of development, but this earliest growth stage is poorly known because dinosaur embryos are rare.  Embryos can potentially tell us how dinosaurs developed and grew very early on in life and if they are more similar to birds or reptiles in these respects.”

Professor Erickson and his team ran the embryonic jaws through a CT scanner to visualise the forming dentitions (teeth).  Then, they extracted several of the teeth to further examine them under sophisticated microscopes.

Researchers found what they were looking for on those microscope slides.  Growth lines on the teeth showed researchers precisely how long the dinosaurs had been growing in the eggs.

Embryonic Remains of a Hypacrosaurus

Hypacrosaurus embryo fossil.

The fossilised remains of a Hypacrosaurus embryo.

Picture Credit: Darla Zelenitsky (University of Calgary)

Professor Erickson added:

“These are the lines that are laid down when any animal‘s teeth develops.  They’re kind of like tree rings, but they’re put down daily.  We could literally count them to see how long each dinosaur had been developing.”

The team’s research indicates that the sheep-sized Protoceratops took three months to hatch, whilst the much larger Hypacrosaurus took six months to incubate.

Fellow author of the study, palaeontologists Mark Norell (American Museum of Natural History), said:

“Dinosaur embryos are some of the best fossils in the world.  Here, we used spectacular fossil specimens collected by American Museum expeditions to the Gobi Desert, coupled them with new technology and new ideas, leading us to discover something truly novel about dinosaurs.”

The Implications for a Species with a Relatively Long Incubation Period

This study suggests that, in the two species examined, the incubation period of the dinosaurs has more in common with primitive reptiles than with their close relatives the birds.  Dinosaur eggs would have been vulnerable to attack from predators, or at risk from flooding, trampling and other dangers for far longer than previously thought.  The long incubation period could have contributed to the extinction of the Dinosauria at the end of the Cretaceous.  Most palaeontologists now believe that the majority of the Dinosauria were endothermic (warm-blooded).  If this is the case, then they would have required considerable resources to grow quickly once hatched to reach breeding age.  Using this data, it can be postulated that decimated populations after a global catastrophe such as an extra-terrestrial impact event or excessive volcanic activity may not have been able to recover.  Essentially, the dinosaurs may have been out-competed to some extent by the rapidly breeding small mammals or the birds with their speedier egg incubation rates.

Professor Erickson concluded:

“We suspect our findings have implications for understanding why dinosaurs went extinct at the end of the Cretaceous period, whereas amphibians, birds, mammals and other reptiles made it through and prospered.”

To read an article that suggests a seed-eating habit helped the birds survive the K-Pg extinction event: Seed-eating May Have Helped the Aves Survive the End-Cretaceous Extinction Event

The Effect on Dinosaur Migration Theories

If dinosaur eggs took a long time to hatch, then the idea of dinosaurs undertaking extensive migrations in order to reach seasonal breeding grounds can be doubted.  Many scientists believe that North American dinosaurs migrated northwards to the Arctic circle during the summer having nested in the more temperate lower latitudes.  Longer incubation periods make these sorts of long migrations more unlikely.

This research was supported by the National Science Foundation and Everything Dinosaur acknowledges the assistance of Florida State University in the compilation of this article.

165 Million-Year-Old Dinosaur Footprints Damaged

Police Investigation after Isle of Skye Dinosaur Prints Damaged

The police are hunting a man suspected of damaging two 165 million-year-old dinosaur footprints by attempting to make plaster casts of them.  The alleged vandalism occurred at An Corran beach, Staffin on the Isle of Skye.  This site is famous for its numerous dinosaur footprints and tracks that have been preserved in sandstone exposures along the shoreline.

The incident was confirmed in the official Lochaber & Skye Police Twitter feed which stated:

“Unfortunately, we can confirm we are investigating reported damage to the dinosaur footprints at Staffin yesterday. Were you in the area?  It would appear a male driving a campervan was possibly responsible for pouring plaster into two of the prints.”

One of the Three-toed Dinosaur Prints at An Corran Beach

Dinosaur footprint (Isle of Skye).

One of the three-toed dinosaur prints from the An Corran beach near Staffin (Isle of Skye).

Picture Credit: John Allan with additional annotation by Everything Dinosaur

The picture above shows one of the three-toed tracks that are exposed at low tide along the beach at An Corran.  The ten pence coin provides scale.

Middle Jurassic Footprints

The Isle of Skye is famous for its extensive dinosaur tracks and footprints.  The majority of the prints located at Staffin represent the movement of large Ornithischian dinosaurs (Ornithopods).  These trace fossils and others like them on the island, are helping palaeontologists to learn more about the different types of dinosaur that roamed this part of Europe some 165 million-years-ago.

Last December, Everything Dinosaur reported on the discovery of a series of Sauropod dinosaur prints in Duntulm Castle Bay, around ten miles from the An Corran site.  This discovery helped to reinforce the view that the sediments on the Isle of Skye preserve a unique record of the large biota that existed during the Bathonian and Callovian faunal stages of the Middle Jurassic of Europe.  To hear that the actions of a thoughtless and selfish individual may have damaged these rare fossils is very sad.

To read about the discovery of the Duntulm Castle prints: Isle of Skye Sauropods and their Watery World

Attempting to make casts or interfere with the prints could cause irreparable damage to these extremely rare trace fossils.  The local council’s Education Chairperson Drew Millar commented:

“It’s absolutely shocking that someone would go to such lengths to destroy something that’s been around for such a long time.  This is one of the major tourist attractions on Skye, some of the oldest proof of dinosaurs in this part of the world.”

Dinosaur Fossil Site Vandalism

Sadly, such incidents are becoming increasingly common.  It is not just the actions of overzealous fossil hunters, some of the recent acts of vandalism have been motivated by a desire to make money by selling fossils illegally.  In 2012, Everything Dinosaur reported on the removal of fossil dinosaur footprints from a site in the Vale of Glamorgan (Wales).

Late Triassic Dinosaur Tracks in the Vale of Glamorgan

Vale of Glamorgan dinosaur tracks.

Dinosaur Tracks from the Late Triassic.

To read an article about the Welsh dinosaur fossil theft: Dinosaur Footprints Stolen from the Vale of Glamorgan

Commenting on the reported An Corran beach fossil damage, a spokesperson from Everything Dinosaur stated:

“This is really sad news, let’s hope the damage is not too significant.  We suspect the perpetrator knew something about this particular fossil site, as the sandstone prints are usually only exposed at low tide and they are often covered by a layer of sand.  It is only after bad weather in winter that the sea washes away the sediment revealing the prints.”

Lochaber and Skye law enforcement officers have appealed for witnesses and have asked for anyone with any knowledge of the incident to come forward.

Note

Everything Dinosaur team members contacted the museum at Staffin for clarification of this story.  The incident did involve a member of the public attempting to make a plaster cast from a footprint.  However, it was a Theropod footprint that was involved and not Ornithopod as stated in the media reports.

Favourite Articles of 2016 (Part 2)

Favourite Blog Articles July to December 2016

Here is the second part of our feature that highlights the favourite posts on this blog, as suggested by Everything Dinosaur team members.  Yesterday, we published our review of the first six months of 2016, here is the lowdown on our personal favourites from July through to December.

To read about our favourite Everything Dinosaur blog articles January to June 2016: Favourite Everything Dinosaur Blog Articles (Part 1)

July

Summer was here, although the weather was not much to write home about, good job there were plenty of palaeontology themed news stories to keep us occupied.  In July 2016, we wrote about the announcement of a new, dinosaur themed novel by the “Jurassic Park” author Michael Crichton.  Cambrian suspension feeders, the brains of lungfish, a new two-fingered meat-eating dinosaur from Argentina (Gualicho shinyae) and the heart-warming story of the return of Pterosaur fossils to Lebanon.  However, our personal favourite story that month came from South America, the footprint of a huge, meat-eating dinosaur, very probably an enormous abelisaurid had been discovered in Bolivia.

That’s a Very Large Trace Fossil!

A footprint of a giant abelisaurid dinosaur.

Huge meat-eating dinosaur footprint discovered in southern Bolivia.

Picture Credit: EFE

To read the story: The Footprint of a Giant Abelisaurid

August

Everything Dinosaur staff may have been busy preparing their dinosaur workshops for the start of the school year, but that did not stop them writing a blog article every day in August.   The team wrote about Marsupial Lions, Chinese primate fossils, the oldest Archaeopteryx found to date, Late Carboniferous shark cannibals and, continuing the Elasmobranchii theme, that a horror film starring Megalodon would be released soon.  Our favourite article was published at the very end of the month, a story about the recently described “Monster of Minden”, fragmentary fossils that suggest that some 163 million years ago, a giant meat-eating dinosaur roamed the land which we now know as Northrhine-Westphalia (Germany).

Wiehenvenator albati – Giant Megalosaur of Germany

The skull and jaws of Wiehenvenator.

The skull and jaw fossils located in their anatomical position (Wiehenvenator).

Picture Credit:

Wiehenvenator article: The Monster of Minden

September

Stories and features about Long-tailed Pterosaurs, how dogs assisted our ancestors, huge dinosaurs of the Gobi Desert and microbial structures that might have existed some 3.7 billion years ago helped take our minds off the shortening days and the falling leaves.  However, our favourite article was published on September 15th.  It described the research undertaken to reveal the camouflage and countershading of the Early Cretaceous dinosaur Psittacosaurus, just a few weeks later, team members were able to view the Psittacosaurus fossil, upon which this research was based, for themselves.

A Model of Psittacosaurus Showing the Countershading as Suggested in the New Study

Psittacosaurus model in the Bristol Botanic Garden.

Psittacosaurus photographed in the Bristol Botanic Garden.

Picture Credit: Jakob Vinther (model made by Bob Nicholls)

Psittacosaurus Colours and Camouflage: Calculating the Colours of Psittacosaurus

October

 Two new species of British Ichthyosaur swimming into view, the extremes found in Tetrapod limbs, giant Titanosaurs, dinosaur brains from Bexhill-on-Sea and the fossils of an Australian prehistoric swordfish all featured in October.  The article we have singled out concerns the meticulous research undertaken to identify the vocalisation organ in the fossilised remains of a Late Cretaceous bird.  This study, literally provided a “sound bite” of life in the Late Cretaceous of Antarctica, around 66 million years ago.

Vegavis iaai – Honking with Dinosaurs?

The vocalisation of dinosaurs and birds.

Vegavis takes off whilst a male Theropod dinosaur vocalises close by.

Picture Credit: Nicole Fuller/Sayo Art for University of Texas at Austin.

Birds that honked in the Late Cretaceous: Ancient Voice Box Provides an Insight into Late Cretaceous Dawn Chorus

November

Highlights last month included writing about the decoding of the Ginkgo genome, the hunt for Troodon, proteins found in fossil dinosaur claws and the myriad of new models coming into Everything Dinosaur’s warehouse next year.  We focus on an article that was based on research published in “Current Biology”.  The fossils of a lagerpetid (dinosaur precursor) and an early dinosaur had been discovered in the same rocks.  This was the first time that this had been recorded and these fossils challenged existing ideas about when the Dinosauria became the dominant terrestrial vertebrates.

The Skull of the Sauropodomorph Dinosaur Buriolestes

Buriolestes skull at the dig site.

The skull of the sauropodomorph Buriolestes.

Picture Credit: Cabreira et al

The article: Just When Did the Dinosaurs Dominate the Land?

December

Fossilised bacteria shedding light on life before oxygen, the variation in body size within Australopithecus afarensis, gorgonopsids with benign tumours, Didelphodon with a bite more powerful than a Hyena, all worthy contenders for December, but we could not let the opportunity pass to comment once again on one of the most remarkable fossil discoveries made, not just this year, but perhaps this Century.  December saw the publishing of a scientific paper on the discovery of part of a dinosaur tail preserved in burmite (amber from Myanamar).

The Tale of a Tail

A tiny dinosaur tail preserved in amber.

The exquisitely preserved dinosaur tail in amber.

Picture Credit: R. McKellar/Royal Saskatchewan Museum

Dinosaur tail preserved in amber: The Tale of a Dinosaur Tail

This story, perhaps more than any other article we have published on the Everything Dinosaur blog, demonstrates that there are still some amazing fossil discoveries to be made.  Who knows what news stories will feature on this blog site in 2017?  We could make some predictions, that might make a theme for a feature published in the early New Year, or we could just wait and see…

Favourite Articles of 2016 (Part 1)

Favourite Articles January to June 2016

At Everything Dinosaur, we try and post up an article on this blog site every day.  This is quite a challenge considering all our other projects and activities, however, as a result of our work on this particular weblog we have managed to build up a huge amount of information, features and articles chronicling (for the most part), advances in the Earth sciences and new fossil discoveries.  Several readers have emailed us and asked us to highlight some of our own favourite news stories that we have written about over the last twelve months or so.  With over 350 articles to choose from, that’s quite a tough challenge, but one we readily accept, so here are our favourites from the first six months of 2016.

January

January 2016 saw us writing about Canada’s first Dimetrodon, dinosaur trace fossils that suggested courtship displays and the discovery of a giant crocodile’s fossils in Tunisia.  However, our favourite story relates the tale of a beachcomber finding proof that enormous elephants once roamed the Isle of Wight.  Fossil hunting is an activity that is not just for the professionals if you look in the right places and get lucky, you too can make an important discovery that contributes to scientific understanding.

 Finder of the Prehistoric Elephant Fossil Paul Hollingshead Poses with his Proud Children

Isle of Wight prehistoric elephant fossil discovery.

Paul and his family show off their fossil find behind an Iguanodon exhibit.

To read the article: Prehistoric Elephants Roamed the Isle of Wight

February

There was no shortage of news stories in the shortest month of the year.  During February, we blogged about Terror Birds of the High Arctic, Doedicurus DNA and the discovery of a new abelisaurid from South America, that might turn out to be one of the smallest of these meat-eating dinosaurs described.  However, our favourite piece was posted up on February 10th, when we wrote about the discovery of two new types of suspension feeding Cretaceous fish.  Plus, we also got the opportunity to publish a painting by the brilliant and so talented palaeoartist Bob Nicholls.

An Illustration of One of the Giant Cretaceous Plankton Feeders – Rhinconichthys

An illustration of Rhinconichthys.

Large filter-feeding fish of the Cretaceous.

Picture Credit: Bob Nicholls

To read the article: Cretaceous Big Mouths!

March

Polar dinosaurs, the demise of the Ichthyosaurs caused by climate change and a study linking the extinction of the hominin H. floresiensis to our (H. sapiens) arrival on the island of Flores, all proved very popular articles with our blog readership, but in the end, we have singled out our story about the resolution of where in the tree of life the bizarre Tully Monster sits.  After six decades of debate, an international team of researchers, including scientists from Yale University, published a paper that classified Tullimonstrum gregarium as a soft-bodied vertebrate, one that is related to extant jawless fish such as Hagfish and the Lamprey.  The Tully Monster had finally found a home.

One of the Strangest Creatures That Ever Lived is Finally Classified

The bizarre Tullimonstrum gregarium.

The “Tully Monster” is classified as a soft-bodied vertebrate.

Picture Credit: Sean McMahon (Yale University)

Tully Monster Riddle solved: Tully Monster Puzzle Solved

April

Talk about “April showers”, we were showered with press releases from museums and universities in April, leading us to blog about all sorts of weird and wonderful things – ancient arachnids, a Silurian “kite runner”, prehistoric dolphins, seed-eating Late Cretaceous survival strategies and the fifty-million-year dinosaur decline.  Our favourite article, as agreed by Everything Dinosaur team members, was written on April 17th, a story about a dedicated graduate student working alongside some of the most famous palaeontologists in the world, who identified a new species of dinosaur – Apatoraptor pennatus.

A New Species of Late Cretaceous Dinosaur from Canada (A. pennatus)

Apatoraptor pennatus

The presence of ulnar papillae on the ulna (bone of the forelimb) indicates the presence of long feathers on the arm.

Picture Credit: The equally talented palaeoartist Sydney Mohr

Apatoraptor news story: Canadian Dinosaurs were Show Offs

May

Giant Patagonian Titanosaurs, baby Titanosaurs, Atopodentatus unzipped, a new species of prehistoric dog, exquisite horseshoe crab fossils from Nova Scotia, bizarre Brazilian crocodiles and calculating the bite force of a Stegosaurus, these were just some of the stories that occupied our writing team.  A favourite, was one that was published on “Star Wars day” – May 4th, tiny three-toed tracks preserved in rock indicate that some of the Theropod dinosaurs may have been very small indeed.   Team members at Everything Dinosaur are aware of a growing body of evidence to suggest that some members of the Theropoda were no bigger than a mouse, we have nick-named this group “leaf litter dinosaurs”.  One of these tiny Theropods ran across a stretch of mud some 125 million years ago and its prints were preserved, providing yet another tantalising clue to miniature dinosaurs, the genus Minisauripus was erected, a name for a dinosaur distantly related to Giganotosaurus and Tyrannosaurus rex, but no bigger than a sparrow.

Minisauripus Runs Across the Mud Flat Chased by a Bigger Theropod Dinosaur

The tiny dinosaur Minisauripus.

Minisauripus, potentially the smallest dinosaur known to science.

Picture Credit: Zhang Zongda/China Daily

To read about Minisauripus: The Smallest Dinosaur of All?

June

Was the primordial snake Tetrapodophis an accomplished swimmer?  What’s the significance of ancient rock paintings found in a remote cave 7,000 feet up in the Alps?  What did the giant meat-eating dinosaur, whose fossilised tracks were found in India, look like?  How do you build a museum to house the bones of the biggest dinosaurs who ever lived?  These and a whole range of other questions were tackled in June 2016, but the article we have chosen to highlight involves the discovery of a new species of British marine reptile made by the English palaeontologist Dean Lomax.  The new species is an Ichthyosaur (Wahlisaurus massarae), the fossil specimen “nosedived” into sediment prior to permineralisation and this unusual taphonomy prevented a new species of marine reptile from surfacing until the middle of June 2016.

Wahlisaurus massarae – A New Species of British Marine Reptile

New species of Early Jurassic Ichthyosaur announced.

New species of Early Jurassic Ichthyosaur announced.

Picture Credit: James McKay

To read the article: A New Species of British Marine Reptile Surfaces

 Part two of this article, a list of our favourite articles published in the last six months will be posted up shortly.

Scientists Build Three Dimensional Future Human

Researchers Create “Trillennium Man”

Interactive three-dimensional models of human joints, showing how common medical complaints have arisen and how we are likely to evolve in the future, have been created at Oxford University.  The research was led by Dr Paul Monk (Nuffield Department of Orthopaedics, Rheumatology and Musculoskeletal Sciences) and it has led to the creation of a computer model of a human skeleton, one that represents a possible individual living around the year 6017 AD.  This individual has been nick-named “Trillennium Man”.

The Research Team Plotted the Evolution of Key Tetrapod Joints

Studying how the human body will evolve.

“Trillennium Man” plotting the evolution of key joints in the human body.

Picture Credit: Oxford University

Dr Monk was interested in exploring why patients at his clinic presented with very similar orthopaedic problems.

He explained:

“We see certain things very commonly in hospital clinics, pain in the shoulder with reaching overhead, pain in the front of the knee, arthritis of the hip, and in younger people we see some joints that have a tendency to pop out.  We wondered how on earth we have ended up with this bizarre arrangement of bones and joints that allows people to have these problems.  And it struck us that the way to answer that is to look backwards through evolution.”

Computerised Tomography Used to Assess Three Hundred Specimens

A total of 224 bone specimens were scanned (CT scans), in order to assess how the human body and joints such as the shoulder, hip and knee have evolved and changed over time.  Specimens from the Smithsonian Institute (Washington) and the London Natural History Museum were used in this study.  Tetrapods involved in the research included members of the hominin tribe such as Homo ergaster and Homo erectus as well as a range of other fossils, including some that represent some of the very first terrestrial vertebrates to have lived.  The scans were than mapped using a computer programme to produce three-dimensional images to show how the bones and joints had changed.  This research has provided new insights into the morphological trends with common orthopaedic complaints such as shoulder pain and anterior knee discomfort.

The Bones of Australopithecus afarensis (Lucy) were Incorporated into the Study

"Lucy" A. afarensis discovered in 1974.

The fossilised bones of Lucy (approximately 40% of the skeleton).

Picture Credit: The Hidden Treasures of Ethiopia

Considering Future Potential Human Joint Problems 

By extrapolating the mathematical models, the research team could attempt to plot how our bodies and their key joints will evolve in the future.

Dr Monk added:

“Throughout our lineage we have been adapting the shape of our joints, which leads to a range of new challenges for orthopaedic surgeons.  Recently there has been an increase in common problems such as anterior knee pain, and shoulder pain when reaching overhead, which led us to look at how joints originally came to look and function the way they do.  These models will enable us to identify the root causes of many modern joint conditions, as well as enabling us to anticipate future problems that are likely to begin to appear based on lifestyle and genetic changes.”

Both quadrupeds and bipeds were included in the study, the research even involved examining how dinosaurs with their digitigrade and semi-digitigrade stance evolved and changed over time.

Commenting on the significance of this research, Dr Monk concluded:

“Current trends reveal that the modern shapes of joint replacements won’t work in the future, meaning that we will need to re-think our approach for many common surgeries.  We also wanted to see what we’re all going to look like in the future, and to answer questions such as ‘are we evolving to be taller and faster or weaker’, and ‘might we be evolving to need hip replacements earlier in the future?’”

Human Hip Bones Evolving

As our distant ancestors adopted a bipedal method of locomotion so the femur (thigh bone) changed.  The neck became gradually thicker to help support body weight.  The thicker the neck of the bone in the femur the greater the likelihood of arthritis in the hip joint.  Orthopaedics have suggested that this thickened neck of the femur might be a reason why our species is prone to hip problems.

Over Millions of Years the “Neck” of the Femur has Become Thicker

Human femur evolution.

Neck of the hominin thigh bone has become broader to support our weight.

Picture Credit: Oxford University

In the picture above, the proximal end of a human femur (H. sapiens), has been modelled using the CT scans (right) and this is compared to the model produced from scans of an early hominin (left).  The red arrows indicate the region of the neck of the thigh bone that has become thicker.

Everything Dinosaur acknowledges the assistance of the University of Oxford press room in the compilation of this article.

Limusaurus – Dinosaur Species Lost Teeth as it Grew Up

Limusaurus – Shed Teeth as it Grew

An international team of scientists, including researchers from the Chinese Academy of Sciences and George Washington University (United States), have made a remarkable discovery regarding the Early Late Jurassic Chinese Theropod dinosaur Limusaurus (L. inextricabilis).  As this dinosaur grew it gradually shed its teeth and a beak formed.  This is the only example of this known from the Class Reptilia, no other reptile extinct or otherwise, lost its teeth and formed a beak after birth.  This research could shed new light on how birds are related to dinosaurs as well as specifically addressing the process of the evolution of beaks in the Aves (birds).

The researchers propose that young dinosaurs were carnivorous, eating insects and small vertebrates, whilst the adults were most likely herbivores.

Scientific Paper Explores the Ontogeny of the Ceratosaurian Theropod Limusaurus

Limusaurus illustrated.

Young Limusaurus dinosaurs were carnivores as they grew up they probably switched to a herbivorous diet.

Picture Credit: Yu Chen

Limusaurus inextricabilis – “Mud Lizard”

Limusaurus was named and scientifically described in 2009, from a series of fossils found in ancient “death traps”, muddy mires which the small, bipedal dinosaurs became trapped in and unable to free themselves, (the binomial name means “mud lizard that could not extract itself”, a reference to how this group of Ceratosaurian dinosaurs met their fate.  A number of specimens are known ranging from youngsters, estimated to be around twelve months of age, to juveniles, sub-adults and more mature individuals estimated to have been approximately ten years old when they died.

Josef Stiegler, a graduate student at George Washington University and co-author of the scientific paper published in the journal “Current Biology” stated:

“For most dinosaur species, we have few specimens and a very incomplete understanding of their developmental biology.  The large sample size of Limusaurus allowed us to use several lines of evidence including the morphology, micro-structure and stable isotopic composition of the fossil bones to understand developmental and dietary changes in this animal.”

Nineteen Specimens – Placed into Six Ontogenetic Stages

In total, the team had nineteen fossilised skeletons to study.  Anatomical comparisons and CT scans of the jaws and skull helped the scientists identify six distinct ontogenetic stages (stages of growth).  Co-author of the study, James Clark, (Ronald Weintraub Professor of Biology at the George Washington University’s Columbian College of Arts and Sciences), explained that by looking at how this dinosaur changed as it grew up, they could see that over time, individuals lost their sharp meat-eating teeth.  By the time these dinosaurs had reached adolescence they were toothless and they did not grow another set as mature adults.

The Remarkable Ontogeny of Limusaurus

Limusaurus shed teeth as this dinosaur grew.

Limusaurus inextricablis – as these dinosaurs grew they lost their teeth and they developed a beak.

Picture Credit: George Washington University

Seventy-eight ontogenetically variable features were identified in the specimens.  Palaeontologists are aware that many Ornithischian dinosaurs such as ceratopsids (horned dinosaurs) and the duck-billed dinosaurs, change dramatically as they grow into adults, such dramatic changes in an animal’s appearance have not been extensively documented in the Theropoda.  Despite the changes as Limusaurus grew up, the assessment of where this Theropod is nested in the Ceratosaurian family tree remains relatively unchanged.

The Differences Between Individual Dinosaurs at Different Growth Stages

Limusaurus ontogenetic variation.

A juvenile Limusaurus (top) compared to an adult (bottom).

Picture Credit: Journal of Current Biology

Key

(1) straight (juvenile) or ventrally deflected (sub-adult) anterior end of the dentary (downward pointing lower jaw)

(2) relatively deep (juvenile) or elongate (sub-adult) skull

(3) gastroliths absent (juvenile) or present (sub-adult)

(4) short (juvenile) or elongate (sub-adult)

Commenting on the significance of their research, Dr James Clark, (George Washington University) explained:

“This discovery is important for two reasons.  First, it’s very rare to find a growth series from baby to adult dinosaurs.  Second, this unusually dramatic change in anatomy suggests there was a big shift in Limusaurus’ diet from adolescence to adulthood.”

Carnivore and then Herbivore

The Limusaurus specimens that represented stage 1 (very youngest animals), had a total of forty-two teeth.  Stage 2 had thirty-four, whilst in the most mature stages from stage 4 onwards, the specimens were toothless (edentulous).  Gastroliths were found in association with larger individuals, and significantly, the size and number of the stones seemed to increase as the dinosaur matured.  The presence of stomach stones indicates a herbivorous diet, a switch from meat-eating to plant-eating as the dinosaur grew up was also suggested by carbon and oxygen isotope analysis from bone samples.

Carbon Isotope Composition of L. inextricabilis Compared to other Dinosaurs from the Upper Shishugou Formation

The diet of Limusaurus.

Bone carbon and oxygen isotopes show a change in diet for Limusaurus as it grew older.

Picture Credit: Current Biology

The diagram above shows the carbon/oxygen isotope analysis from the Limusaurus fossil material.  Blue polygons show the ranges for herbivorous behaviour, whilst the red polygons show likely carnivorous feeding behaviour.  The various Limusaurus ontogenetic ranges are plotted.  Growth stages one to three indicate likely meat-eating habit in young and juvenile Limusaurus specimens, with a switch to a plant-eating diet (later stages).  The data is plotted alongside meat-eating, plant-eating contemporaries of Limusaurus from the Upper Upper Shishugou Formation (Oxfordian faunal stage of the Early Late Jurassic).  The dashed lines represent the data related to sub-adult Limusaurus.

Close to the Bird Lineage

Limusaurus belongs to that part of the Theropoda that is believed to be closely allied to the evolutionary ancestors of the birds.  Dr Clark et al in the formal description of this dinosaur in 2009, described the species’ hand development (manus) and noted that the reduced first digit might have been transitional towards the digit configuration of modern birds (digits II, III and IV).  This new data could help scientists to understand how birds lost their teeth and the beak evolved.

To read an article on the naming and describing of Limusaurus: Chinese Ceratosaur and Dinosaur/Avian Links

Commenting on why these dinosaurs adapted to a different diet as they grew older, a spokesperson from Everything Dinosaur said:

“The adoption of a new feeding strategy as the animal matured might reflect a degree of opportunism by this species.  Faced with an abundance of plant food within easy reach, it might have been advantageous for this dinosaur to feed on vegetation rather than expanding energy in the pursuit of prey.  Perhaps, as the animal grew, plant food became an increasing proportion of its diet, this dinosaur transitioning from a carnivore/omnivore phase through to a stage where plant matter made up by the far the greatest proportion of its calorific intake.”

The research was performed by Shuo Wang of the Capital Normal University and Mr. Stiegler under the guidance of Xu Xing of the Institute of Vertebrate Palaeontology and Palaeoanthropology, and Dr Clark.  A National Science Foundation grant funded the research.

The scientific paper: “Extreme Ontogenetic Changes in a Ceratosaurian Theropod” published in the journal “Current Biology”

Extinct Human Cousin Helped the Inuit Survive

Analysis of the Genome of an Inuit Population Hints at Denisovan Influence

A team of international scientists including researchers from the New York Genome Centre and the University of California Berkeley, have analysed the genome of a population of Inuit from Greenland and identified components that may originate from the Denisovans or a related archaic human species.  The “caveman” genes have helped these people adapt and survive in cold climates.  In the first genomic analysis of Inuit people from Greenland, the scientists scrutinised two genes, namely TBX15 and WARS2 that seem to be a close match to an archaic human genetic variant, potentially Denisovan or some other closely related Denisovan-like species that has yet to be found in the fossil or anthropological records.  TBX15 is known to help the human body cope with cold temperatures and influences the distribution of body fat, whilst WARS2 encodes the mitochondrial tryptophanyl-tRNA synthetase and may have a role in managing blood vessels associated with the heart.

An Image of an Inuit Female – Cold Adaptations Inherited from an Archaic Human Species

Inuit female.

An Inuit woman.

Picture Credit: Getty Images

Who are the Inuits?

The Inuit are collection of culturally similar peoples that inhabit the Arctic regions of Alaska, Canada and Greenland.  Although widespread throughout the Arctic Circle, most anthropologists believe that the ancestors of the Inuit people originated from Siberia.  The Inuit have made their home in one of the harshest environments on Earth and their traditional lifestyle is based around hunting.  As a result, their diet is rich in protein, low in carbohydrates and despite the lack of agriculture and plant cultivation, the people derive vitamins and other trace elements essential to health from fish/meat based foods supplemented by seasonal berries, herbs and edible seaweeds.

Dr Fernando Racimo (New York Genome Centre) and a co-author of the scientific paper published in the “Journal of Molecular Biology and Evolution” commented:

“The Inuit DNA sequence in this region matches very well with the Denisovan genome, and it is highly differentiated from other present-day human sequences, though we can’t discard the possibility that the variant was introduced from another archaic group whose genomes we haven’t sampled yet.”

Who were the Denisovans?

The Denisovans are a third species of hominin, closely related to Neanderthals but distinct enough to be regarded as a separate human species.  In 2008, scientists excavating 40,000-year-old cave deposits in southern Siberia, unearthed a single tooth and a tiny finger bone.  The tooth can from an adult human, the finger bone from a child.  Genetic analysis of nuclear DNA extracted from the digit gave the researchers quite a surprise.  When this DNA was compared to that genome of modern humans and Neanderthals, it was different.  Here was evidence of a new species of hominin that lived until quite recently.  This new species was named “Denisovan” after the cave in which the bone and the tooth were found.  The Denisovans, evidently had brown hair, eyes and dark skin, at least, this is indicated by the genetic information retrieved from the single finger bone.

To read an article about the discovery of the Denisovans: X-woman! A Third Species of European/Siberian Early Human Discovered

A View of the Entrance to the Cave (southern Siberia) Where Denisovan Fossil Evidence was Found

Denisovan cave.

A view of the entrance to the cave, inside which, fossil evidence of Denisovans was found.

Picture Credit: Max Planck Institute

Intriguingly, geneticists have also found an overlap between the Denisovan genome and that of some modern groups of Asians and Pacific Islanders.  A number of theories regarding this have been put forward, for example, it has been suggested that Denisovans living in eastern Eurasia interbred with modern humans that were migrating into the region.  When these modern human pioneers reached outlying islands of the Asian continent such as Papua New Guinea, they brought the mixed H. sapiens/Denisovan DNA within that population, leading to the “echo” of Denisovan DNA found today.  Other researchers have argued that the enigmatic Denisovans were much more widespread, ranging far across Asia, although the lack of fossil evidence and calculated genetic diversity contained within a population, indicates that Denisovan numbers were never very high.

Further information regarding the spread of modern human species and the influence of archaic human lineages on the genomes of modern people: Out of Africa Earlier Than Thought!

The research team analysed the genomes of around two hundred Inuit from Greenland in order “to identify genes responsible for biological adaptations to life in the Arctic.”  They conclude that the Inuit variant of the TBX15/WARS2 region first came into modern humans from an ancient human line.

A Lateral View of the Ancient Human Molar Ascribed to the Denisovan Species

Denisovan fossil molar.

Ancient human tooth, ascribed to Denisovan.

Picture Credit: Max Planck Institute

Dr Racimo added:

“The Inuit DNA sequence in this region matches very well with the Denisovan genome and it is highly differentiated from other present-day human sequences, though we can’t discard the possibility that the variant was introduced from another archaic group whose genomes we haven’t sampled yet.”

Denisovan Genes in Tibetans

Passing on genetic material due to interbreeding between hominin species, that favoured modern humans and helped them adapt to harsh environments is not a new phenomenon.  The modern-day inhabitants of the Tibetan plateau are able to cope with living at high altitude as they have a gene variant that enables them to regulate their production and use of haemoglobin more effectively. Genetic analysis suggests that this characteristic came from the Denisovans.

Professor Rasmus Nielson, the lead author of the scientific paper stated:

“We have very clear evidence that this version of the gene came from Denisovans.  This shows very clearly and directly that humans evolved and adapted to new environments by getting their genes from another species.”

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