Category: Dinosaur and Prehistoric Animal News Stories

“Sophie” The Stegosaurus at 1.6 Tonnes

Scientists Calculate the Body Mass of a Stegosaurus

A team of scientists based at the Natural History Museum (London), have calculated the weight of “Sophie”, the beautifully preserved and nearly complete Stegosaurus fossil skeleton that has been on display at the museum since last November.  This is the first set of data to be released about this, most iconic dinosaur, famous for its tiny brain and those remarkable plates running along its back.  The research team headed by Dr. Paul Barrett hope to release more findings throughout the year.  The weight of the 5.6 metre long animal, has been calculated at 1.6 Tonnes, not a bad size for a dinosaur that was not yet fully grown when she died.

“Sophie” The Stegosaurus Weighs 1,600 Kilogrammes

The preserved skeleton of "Sophie" the Stegosaurus.

The preserved skeleton of “Sophie” the Stegosaurus.

Picture Credit: Natural History Museum (London)

Team members at Everything Dinosaur predicted at the beginning of the year that much more information would be known about Stegosaurs over the course of 2015 thanks to the palaeontologists and other scientists based at the museum.  It was one of the company’s “palaeontology predictions” for this year.  Ironically, despite this dinosaur’s popularity (it came in at number four in Everything Dinosaur’s most popular prehistoric animals survey), very little academic work has been carried out on Stegosaurus for more than eighty years.

Palaeontologists like Dr. Charlotte Brassey, the lead author of a paper about “Sophie” and her body weight are changing all that, the doctor and her colleagues will be embarking on a series of research projects aimed at helping us to learn more about this Late Jurassic herbivore.  The first research paper has just been published in the journal “Biology Letters”.  Knowing the body mass of an animal is very important as it allows researchers to answer a lot more questions once this data has been established.

Dr. Brassey explained:

“If we want to estimate how fast an animal runs, you need body mass; if you want to say something about their metabolism, you need to know their body mass.  So, yes, we’re really glad that we’ve been able to get hold of this very early on, and now what I’m looking to do is begin to strap muscles on to our computer models so that we can get her walking to say something about locomotion.”

The specimen, originally from Wyoming, consists of over 360 individual bones, about 80% of this material is actually fossil, the rest of the skeleton has been built up using casts of other specimens and reconstructions of missing pieces.  Prior to the skeleton being put on display, each one of these objects was scanned and mapped onto a computer programme using a Computer Aided Design (CAD) package.  It was from this modelling data that an estimated body mass of 1.6 Tonnes was calculated.  Although not fully grown, “Sophie” still weighed more than the fifteen players in England’s rugby team combined.

More traditional methods of calculating body weight involve measuring the circumference of the femur (thigh bone) and the humerus (upper arm bone).  The ratios between these two bones and body weight in extant animals is well established, the bigger the circumference the heavier the animal is the simple rule.  The new CAD modelling technique agrees with the figure for body mass calculated using the measurements from the major limb bones.  The scientists are confident that their data is correct and “Sophie” weighed in at around 1.6 Tonnes.  This suggests that a fully grown Stegosaurus stenops probably weighed more than three thousand kilogrammes.

A Fully Grown Stegosaurus Probably Weighed More Than Three Tonnes

A remarkable dinosaur.

A remarkable dinosaur.

Picture Credit: Everything Dinosaur

We look forward to learning more about Stegosaurs, one question that does need answering for example, is this, should we refer to this Stegosaurus as “Sophie”?  Will the scientists be able to confirm that this individual was a female?

Sir Richard Owen Gets Blue Plaque

Sir Richard Owen Honoured with Blue Plaque

Sir Richard Owen, the 19th Century anatomist and palaeontologist who first used the term dinosaur, has been honoured by the Society of Biology by having a blue heritage plaque installed at his former school, Lancaster Royal Grammar.  The plaque was unveiled yesterday at a small ceremony.  Blue plaques serve to act as a historical marker, indicating that a notable person was associated with a place or that an important, historical event occurred at that location.  This blue plaque commemorates that fact that Sir Richard (knighted in 1884), attended the school from 1809-1819.

The Blue Plaque Erected at Lancaster Royal Grammar School

Sir Richard Owen honoured.

Sir Richard Owen honoured.

Picture Credit: LRGS

 Undoubtedly, Sir Richard Owen was a very talented scientist and an extremely clever man.  Although he did not impress all his tutors whilst at Lancaster Grammar School.  One school master described him as “impudent” and doubted whether the son of a merchant would ever amount to very much.  Although Sir Richard gained a great deal of acclaim during his lifetime and certainty did make a huge contribution to science, by all accounts he had a very egregious character.  There are a number of accounts of him plagiarising the work of his contemporaries and he was very critical of the work of some of his peers.  For example, the then, plain Richard Owen disputed much of the evidence put forward to support the theory of natural selection as suggested by Charles Darwin in the “Origin of Species”, which was first published in 1859.  Richard Owen seemed to resent the success of others and he has earned a reputation (perhaps deserved), for being quick to condemn the work of others whilst desiring to talk up his own contribution.

To read another article about Sir Richard Owen: Remembering Sir Richard Owen”

In a glittering career, which saw him rise to the top of the Victorian scientific community, Sir Richard Owen was awarded many accolades.  He supervised the first “life-sized” prehistoric animal replicas as part of the Great Exhibition in 1851, he acquired one of the very first Archaeopteryx fossil specimens and studied it in great detail.  He described a vast array of extinct and extant animals and wrote a prestigious amount of academic literature.  Perhaps his most notable achievement was campaigning for and helping to set up the museum now known as the Natural History Museum.  Owen’s “cathedral to nature” opened in 1881.

Sir Richard Owen may be credited with coining the term “dinosaur”, but he was not the first person to note that the strange fossils of ancient animals being found in southern England and elsewhere represented a distinct group of animals.  The German palaeontologist, Hermann von Meyer stated that these ancient reptiles now known as dinosaurs should be considered a separate Order as early as 1832, around ten years before Sir Richard Owen coined the term “Dinosauria”.

A Portrait of the Young Richard Owen

A young Sir Richard Owen.

A young Sir Richard Owen.

In total ten blue plaques are been erected by the Society of Biology to commemorate the contributions to science made by “heroes of biology”.  Other recipients include: Patrick Steptoe, Jean Purdy and Robert Edwards who jointly developed IVF, leading to the world’s first test-tube baby, Louise Brown who was born in 1978, (plaque located at Dr. Kershaw’s Hospice, Oldham) and Sir Anthony Carlisle, an anatomist who helped develop the concept of producing medical statistics.

There is even a plaque being erected to “Dolly the Sheep”, the first mammal to be cloned from an adult somatic cell rather than an embryonic one.  This plaque can be seen at the Roslin Institute (part of the University of Edinburgh), where Dolly lived all her life (1996-2003).  We are not sure quite how Sir Richard Owen would feel about having a plaque erected to honour him at the same time as a sheep gets one, but we suspect that he would be desperately keen to learn more about the science of genetics, which was virtually unknown when he was alive.

Peruvian Paradise for Prehistoric Crocodiles

A Miocene Crocodile Community – from Prehistoric Peru

It’s not just Paddington Bear that heralds from Peru, a team of international scientists writing in the academic journal the “Proceedings of the Royal Society B” have published a paper that describes a rich and diverse wetland ecosystem that thrived thirteen million years ago, jam packed with co-existing Crocodylians.  North-eastern Peru was covered in an extensive tropical wetland during the Middle Miocene Epoch (Serravallion faunal stage), at least seven different species of ancient crocodile lived in this habitat, three of which are entirely new to science.   The crocodile fossils have been excavated from two highly fossiliferous bone beds that document life in South America prior to the formation of the Amazon basin and its rainforest.

As much of north-eastern Peru is now covered in tropical, lowland forest, exposed outcrops of sedimentary rocks are rare, however, a team of researchers from the University of Montpellier, Toulouse University, the American Museum of Natural History, the Naturalis Biodiversity Centre (Holland) and the Department for Vertebrate Palaeontology at the Natural History Museum in Lima have spent more than a decade piecing together information about this ancient ecosystem, one in which a number of specialised Crocodylians co-habited.

 A Mid Miocene Hyperdiverse Crocodylian Community

Hyperdiverse Crocodylian community of Mid Miocene Peru.

Hyperdiverse Crocodylian community of Mid Miocene Peru.

Picture Credit: Javier Herbozo

The picture above illustrates the proto-Amazonian swampland of north-eastern Peru from around thirteen million years ago and three of the Crocodylians that lived in this habitat.  Kuttanacaiman iquitosensis (left), Caiman wannlangstoni (right) and feeding on clams on the lake floor is the short-snouted Gnatusuchus pebasensis.

The research team conclude that with the fossilised remains of at least seven different species present, this ecosystem represents the greatest concentration of crocodile species co-existing in one place at any time in Earth’s history, as recorded in the fossil record.  In comparison, the Amazon rainforest today, is home to just six species of Caiman, but only three species are known to co-exist in the same habitats.  The scientists suggest that the huge range of different Molluscs, creatures such as land and pond snails as well as several types of clams enabled these different types of freshwater crocodile to specialise in feeding on a particular group.  Although vertebrate fossils are rare in the exposed Peruvian Miocene strata, a vast assemblage of Mollusc fossils have been preserved.

Commenting on how this research has helped to fill in the gaps in our knowledge regarding the origins of the Amazon’s rich biodiversity, John Flynn, Frick Curator of Fossil Mammals at the American Museum of Natural History and a co-author on the scientific paper stated:

“The modern Amazon River basin contains the world’s richest biota, but the origins of this extraordinary diversity are really poorly understood.”

It seems that whilst today’s South American Crocodylians are generalists eating a range of prey items, in the Mid Miocene a group of durophagous “shell-crunching” crocodiles evolved, to exploit the huge range of different types of Mollusc.  Clams and snails now only make up a small portion of most Caiman’s diets.

John Flynn went onto add:

“Because it’s a vast rainforest today, our exposure to rocks and therefore, also to the fossils those rocks may preserve, is extremely limited.  So anytime you get a special window like these fossilised “mega-wetland” deposits, with so many new and peculiar species, it can provide novel insights into ancient ecosystems.  What we  have found isn’t necessarily what you would expect.”

Other types of crocodiles known to have lived in this habitat include the bizarre Mourasuchus, a large reptile, that probably fed by filtering zooplankton and other small animals out of the water.  The dangerous Purussaurus also inhabited the waterways.  Attaining lengths in excess of eight metres, this was an apex predator that probably preyed on a range of animals including other types of crocodile.

With three of the species new to science, it demonstrates the diversity of the Order Crocodylia.  One of the most peculiar of all the new crocodile discoveries is Gnatusuchus pebasensis.  This was a short-snouted Caiman with rounded teeth and it is thought that it used its snout to dig in the mud at the bottom of lakes and swampy areas to extract clams and other shelled creatures.  The shells would have been smashed to pieces in the strong jaws with their specialised teeth, designed for crushing.

A Model of the New Prehistoric Caiman Species G. pebasensis

New species of ancient Peruvian crocodile.

New species of ancient Peruvian crocodile.

Picture Credit: Aldo Benites-Palomino

The model in the photograph above was made by Kevin Montalbán-Rivera.

South America remained an island continent until around three million years ago.  Isolated from the rest of the world, a unique fauna and flora evolved, including so it would seem a diverse group of Crocodylians.  The Amazon basin itself did not form with its extensive network of rivers until the Late Miocene, around 10.5 million years ago.  Today, the mighty Amazon drains eastwards into the Atlantic ocean, however, in the Mid Miocene, the lakes, wetlands and swamps drained to the north, through what is now Columbia and Venezuela.  As the Amazon system slowly evolved, so it seems that the large numbers of molluscs and other shelled creatures began to decline, this led to the extinction of many of the different types of crocodile that relied on these creatures for food.

As well as the specialised clam feeders, the research team also discovered the first unambiguous fossil evidence of an ancestor of extant Caimans. This Caiman, named Pebas palaeosuchus (ancient crocodile of the Pebas Formation), had a longer snout better adapted for catching a variety of prey.  It is this evolutionary design that triumphed over the broad but short-snouted Crocodylians, giving rise to modern Caimans.

Rodolfo Salas-Gismondi, lead author of the paper and a graduate student of the University of Montpellier (France), explained:

“We uncovered this special moment in time when the ancient mega-wetland ecosystem reached its peak in size and complexity, just before its demise and the start of the modern Amazon River system.  At this moment, most known Caiman groups co-existed, ancient lineages bearing unusual blunt snouts and globular teeth along with those more generalised feeders representing the beginning of what was to come.”

Fossil Evidence Indicates a Rich Hyperdiversity of Crocodylians

A hyperdiversity of Crocodylians.

A hyperdiversity of Crocodylians.

Picture Credit: Rodolfo Salas-Gismondi

Since 2002, the research team have built up a detailed picture of the various different types of crocodiles that inhabited the ecosystem, as preserved in bone beds associated with the Mid Miocene-aged Pebas Formation.  The skull and jaws, depicted above show the specialist adaptations of the different species.

Key

  1. Gnatusuchus pebasensis – probably fed on molluscs
  2. Kuttanacaiman iquitosensis – probably fed on molluscs
  3. Caiman wannlangstoni – probably fed on molluscs
  4. Purussaurus neivensis – large, apex predator feeding on other vertebrates
  5. Mourasuchus atopus – filter feeder
  6. Pebas palaeosuchus – a generalist, more typical of extant Caiman
  7. Pebas gavialoid – probably fed on fish

Reconstructions by Javier Herbozo.

All these different types of Crocodylians, but alas, it seems, the scientists have not identified a species that could have fed on Paddington Bear’s ancestors, or even marmalade sandwiches for that matter.

Everything Dinosaur acknowledges the assistance of the American Museum of Natural History in the compilation of this article.

Evolution Favours Getting Big

Stanford University Study Tests “Cope’s Law”

Evolution, at least in marine organisms, tends to favour the emergence of bigger animals according to new research published by Stanford University of California.  A trend for “bigness” – a term coined by a Year 3 pupil we overheard the other day during a dinosaur workshop we were conducting at a school, seems to have been present in the oceans of the world, at least since the Cambrian, a time when the first hard-bodied creatures evolved.  This suggests that the path followed by natural selection can be predicted, it indicates that evolution may follow certain rules, at least for one important biological trait – body mass.

It was the American naturalist and palaeontologist Edward Drinker Cope (1840-1897) who proposed a natural law, now referred to as “Cope’s Law” that the ancient ancestors of extant animals were usually much smaller than their modern counterparts.  Building on the research from some of Cope’s rivals, such as the work on the evolution of equines (horses) by Othniel Marsh (1831-1899), Cope postulated that evolution had a tendency to produce larger animals.  The first horses such as Propalaeotherium, known from the famous Messel shales near Frankfurt (Germany), were only sixty centimetres high at the shoulder.  Dinosaurs too, seem to follow this rule, with the very first members of the Dinosauria being just a fraction the size of later types of dinosaur such as the enormous Sauropods Diplodocus, Barosaurus and Apatosaurus from the Late Jurassic.

Getting Bigger Over Time – the Dinosauria

Dinosaurs tended to get bigger over time.

Dinosaurs tended to get bigger over time.

Picture Credit: Everything Dinosaur

This pattern is not consistent across the Kingdom Animalia.  For example, Aves (birds) do not show this trend, very probably as there is a need to reduce weight in order to become more efficient fliers.  Insects too, do not follow this trend, although in the case of the Insecta there are body mass limits probably related to atmospheric oxygen concentrations and the constraints of having an exoskeleton.

However, in one of the most comprehensive research programmes ever undertaken, scientists from the Stanford School of Earth, Energy and Environmental Sciences conducted a review of over 17,000 extinct and extant marine genera.  The study incorporates data from over sixty percent of all the animal types that have ever existed.  The amount of work that had to be done was simply colossal.  Members of the Department enlisted the help of University colleagues, undergraduates and even high school interns to search through the scientific record for measurement data on marine life forms from the Cambrian geological period to today.

 The study published this week in the journal “Science” concludes that over the last 542 million years the mean size of marine animals has increased by 150 fold.  The Stanford research team also discovered that the increase in body size that has occurred since animals first appeared in the fossil record is not due to all animal lineages steadily growing bigger, but rather to the diversification of groups of organisms that were already larger than other groups early in the history of animal evolution.

An Evolutionary Trend for “Bigness” Indicated by Statistical Analysis

Over time there has been a tendency for marine animals to get bigger..

Over time there has been a tendency for marine animals to get bigger..

Picture Credit: Open University

The picture above depicts a typical scene in a shallow Silurian sea about 428 million years ago (Wenlock Epoch).  Analysis of the fossil record indicates that the explosion of different life forms in the Palaeozoic eventually skewed decisively towards larger, bulkier animals.  Measured by volume, today’s smallest marine animals (microscopic crustaceans) are less than ten times smaller than their Cambrian counterparts.  However, at the other end of the scale, perhaps the largest animal known from the Cambrian is Anomalocaris canadensis, which at nearly a metre in length, was huge compared to the other Cambrian fauna it preyed upon, but Anomalocaris at perhaps two to three kilogrammes in weight (estimate), was many thousands of times lighter than today’s largest sea creature the Blue Whale (Balaenoptera musculus).  Body weights of Blue Whales have been calculated at over 190,000 kilogrammes.

The research team also set about trying to work out whether the favouring of bigger sea creatures over time was really driven by evolutionary advantage, or was this trend just a case of serendipity?   Neutral drift is the term used to describe changes in an organism that seem to infer no evolutionary advantage or disadvantage.   A computer model was created and size data from the oldest animals included in the study was incorporated into it.  From this data set a series of simulations were run to see how life in marine environments might have evolved.  Each species used in this part of the research, could either die out, stay unchanged or get bigger or reduce in size.  In the various scenarios that were tested, the version that best matched the fossil evidence was one where there was a genuine size advantage inferred.

One of the lead authors of the research, post-doctoral researcher Dr. Noel Heim commented:

“The degrees of increase in both mean and maximum body size just aren’t well explained by neutral drift.  It appears that you actually need some active evolutionary process that promotes larger sizes.”

As for what those benefits of being big might be, the research team cannot be certain, but larger species may have been able to take greater advantage of resources by being able to swim faster, burrow deeper or to eat larger and more varied types of prey.  Dr. Heim also suggested that the increase in oxygen may also have played a significant role in the evolution of larger animals.

Anomalocaris – Big for the Cambrian but Dwarfed by Today’s Larger Marine Animals

The Terror of the Trilobites - Anomalocaris

The Terror of the Trilobites – Anomalocaris

Picture Credit: BBC Worldwide/Framestore

New Ichthyosaurus Species Honours Mary Anning

Dorset to Doncaster – New Species of Ichthyosaurus Described

It might be one of the best known of all the genera of Mesozoic marine reptiles, but the Ichthyosaurus genus has been becalmed in terms of new additions to the species list.  That is, until a remarkable discovery in the fossil collection of the Doncaster Museum and Art Gallery led to the naming of a new species.  Ichthyosaurus anningae, the first “new” Ichthyosaurus for 127 years.  A paper describing this new species is due to be published in the prestigious academic publication “The Journal of Vertebrate Paleontology” and it is great to see that the trivial name honours Dorset fossil collector Mary Anning, it was Mary along with her brother Joseph, who found the first Ichthyosaurus fossils to be scientifically studied (1811).

The First New Species of Ichthyosaurus to be Described Since the 19th Century

Dolphin-like prehistoric animals.

Dolphin-like prehistoric marine reptiles.

The fossil, representing a sub-adult specimen, had resided in the collection of the Doncaster Museum and Art Gallery since it had been acquired sometime in the early 1980′s.   It was excavated from Lower Jurassic strata of West Dorset, but we at Everything Dinosaur, are unable to provide further information as to who exactly discovered it.  The fossil is believed to have come from the Lower Pliensbachian Stonebarrow Marl Member (Charmouth Mudstone Formation), which forms part of the geology of southern England’s famous “Jurassic Coast”.  The specimen, which measures around 1.5 metres in length is nearly complete, there is a beautifully preserved skull, much of the front portion of the body including ribs and preserved stomach contents.  The assigned holotype (DONMG:1983.98) had been mislabelled as a plaster cast replica.  Team members at Everything Dinosaur recall seeing the image of the fossil used to help promote children’s holiday activities at the Museum, it emphasises the importance of regional museums and their collections.  There are probably a significant number of new species awaiting discovery, not in the cliffs of Monmouth Beach, Lyme Regis, but in the draws and cabinets of museums.

Newest Ichthyosaurus on the Block (I. anningae)

A new species of Ichthyosaurus.

A new species of Ichthyosaurus.

Picture Credit: Dean Lomax and Judy Massare

This is not the first time that a new Mesozoic species has been identified from a museum collection.  Back in 2007, Everything Dinosaur wrote about the discovery made by then PhD student Mike Taylor at the Natural History Museum (London), which led to the naming of a new species of Sauropod dinosaur.

To read the article: How to Find a New Dinosaur – Look in a Museum

Dean Lomax, Honorary Scientist at The University of Manchester, examined the specimen in 2008.  He noticed a number of anatomical differences between this specimen and other types of Ichthyosaur.  Working with Professor Judy Massare (Brockport College, New York), Dean spent over five  years comparing and contrasting the Doncaster Ichthyosaur that had been nicknamed “Fizzy” with other museum specimens from around the world.  Unusual features in the humerus and femur (upper limb bones) along with the humerus length to femur ratio led him to believe that the Doncaster fossil represented something not seen before.  Over 1,000 other Ichthyosaurus fossils were examined during the course of the research, a further four fossils (three most likely of juveniles), were identified as having the same anatomical features as “Fizzy”.

Dean commented:

“After examining the specimen extensively, both Professor Massare and I identified several unusual features of the limb bones that were completely different to any other Ichthyosaur known.  That became very exciting.  After examining over a thousand specimens we found four others with the same features as the Doncaster fossil.”

Professor Massare has worked on a number of Ichthyosaur specimens, most notably a remarkable fossil found in Wyoming.  She used her knowledge of Ichthyosaur anatomy and locomotion to compare and contrast the fossil material.  The strata from which this fossil was extracted dates from the Early Jurassic (Lower Jurassic - Hettangian/Sinemurian–Pliensbachian).  It has been estimated that this fossil material is around 189 million years old. (Pliensbachian faunal stage).  Most Ichthyosaur fossils that date from this stage of the Jurassic are fragmentary, very few articulated specimens with cranial material are known.  The Doncaster fossil is the most complete Ichthyosaur fossil that dates from this time interval.

The upper arm bone (humerus) is short and robust.  The femur (thigh bone), in comparison is very much smaller.  The morphology of the fossil specimens ascribed to this new species, suggest that there were differences in the limb bones of males and females.  Such differences have not been identified before in Ichthyosaurs.  The species name pays tribute to Mary Anning (1799-1847), it was Mary along with other family members who found the fossils of the first scientifically described “fish lizard”.  The very first formal, academic paper describing an Ichthyosaur was published in 1814, the study being based on fossil material found in the Lyme Regis area by the Anning family.  Last year, Everything Dinosaur wrote a short article commemorating the 200th anniversary of this event.

To view this article: Two Hundred Years of Ichthyosaurs

Dean explained:

“Mary worked tirelessly to bring Ichthyosaurs, among other fossils, to the attention of the scientific world.  It is an honour to name a new species, but to name it after somebody who is intertwined with such an important role in helping to sculpt the science of palaeontology, especially in Britain, it is something that I’m very proud of.  In fact, one of the specimens in our study was even found by Mary herself!  Science is awesome.”

It has been a very busy couple of years for Dean, as well as helping to increase our understanding of British marine reptiles, in 2014, his book “Dinosaurs of the British Isles”, co-authored with Nobumichi Tamura was published.  This book provides a comprehensive account of the dinosaur fossils associated with the British Isles and we at Everything Dinosaur strongly recommend it to anyone with an interest in dinosaurs.

“Dinosaurs of the British Isles” – A First, Comprehensive Account of British Dinosauria

A comprehensive guide to British dinosaurs over 400 pages.

A comprehensive guide to British dinosaurs over 400 pages.

Picture Credit: Siri Scientific Press

For more details about the book and to order a copy: Dinosaurs of the British Isles Available Here

This new specimen, helps palaeontologists to understand in greater detail the evolution and radiation of the Ichthyosauria.  I. anningae adds to the number of Ichthyosaurus known from the Pliensbachian faunal stage.  There has now been recorded at least three species (possibly as many as five species) from this time interval.  This is significant, as the discovery of this new species falls between two of the three known major radiations of Ichthyosaur genera.  The numbers and types of Ichthyosaur seemed to have increased around 200 million years ago (Triassic/Jurassic boundary) – Neoichthyosaurian radiation.  A second major radiation occurred around 175 million years ago (Aalenian faunal stage), the Ophthalomosaurid radiation, when many new kinds of “fish lizard” also evolved.

Widespread Ecological Diversity Amongst Early Mammals

Tree-dwellers and Burrowers – Early Mammals More Diverse than Previously Thought

Fossils of two mouse-sized, mammals from China, indicate that some of the earliest known mammaliaforms (extinct relatives of modern mammals), had already diversified and become highly adapted to different ecological niches.  A joint Chinese/U.S. scientific team reporting in the academic journal “Science” discuss the implications for mammalian evolution and describe two new early mammals, one that was arboreal (tree dwelling) and fed on insects and tree sap, the other, a mole-like creature that probably spent much of its life underground.

The tree dweller, named Agilodocodon scansorius lived around 165 million years ago, the subterranean creature called Docofossor brachydactylus was discovered preserved in slightly younger strata, it burrowed underground whilst dinosaurs roamed overhead some 160 million years ago.  Both these creatures are Middle Jurassic Docodonts, an extinct Order of early proto-mammals.

The discovery of these two very different fur covered animals further supports the theory that just like modern-day mammals, Jurassic forms were highly adaptable and early mammals diversified to take advantage of a large range of ecological habitats.

Agilodocodon scansorius – Artists Impression and Skeleton Reconstruction

Early arboreal mammal from north-eastern China.

Early arboreal mammal from north-eastern China.

Picture Credit: University of Chicago (illustration by April Neander)

Commenting on the significance of these fossil finds, Dr. Zhe-Xi Luo (University of Chicago’s Department of Organism Biology and Anatomy), who co-authored the scientific papers stated:

“Before the turn of this century, it was generally thought that Mesozoic mammals could not diversify much in the dinosaur dominated ecosystem.  But fossil discoveries in recent years have built up a different picture.  In the last ten to fifteen years palaeontologists have found many Mesozoic mammals with very interesting functional and ecological specialisations.”

The research team that studied these fossils, was made up of scientists from the Beijing Museum of Natural History and the University of Chicago.  They conclude that Docodonts adapted to a very broad range of environments such as arboreal and subterranean habitats, despite competition from the Dinosauria, other reptiles and early birds.  Agilodocodon was a small, swift  animal with limb and finger bone dimensions that are comparable to modern tree dwelling mammals.  Study co-author David Grossnickle, a graduate student at Chicago University emphasised that it was amazing to see arboreal adaptations occurring so early in the evolutionary history of mammals.  He reflected that this research suggests that some extinct mammalian relatives exploited evolutionarily significant niches, long before true mammals.

An Artists Impression  and Skeleton Reconstruction of Docofossor brachydactylus

Ancient mole-like animal.

Ancient mole-like animal.

Picture Credit: University of Chicago (illustration by April Neander)

The Agilodocodon fossil material came from the Ningcheng County of Inner Mongolia, whilst the Docofossor material came from Hebei Province of China, to the south-east.  Docofossor lived around 160 million years ago. It lived in burrows on shores of  lakes and fed on worms and insects in the soil.  This small creature had reduced bone segments in its fingers, leading to shortened but wide digits, perfect adaptations for digging.  African Golden Moles possess almost the exact same adaptation.  This characteristic is due to the fusing of bone joints during embryonic development.  With African Golden Moles, the development of the digits is influenced by the genes GDF-5 and BMP.  As the extinct Docofossor has a very similar anatomy, the research team conclude that this genetic mechanism may have played a comparable role in early mammal evolution.

Mammals from the Middle Jurassic were once thought to have a very limited ecological footprint, only occupying a few niches in the food web.  However, these two new fossil discoveries along with early finds studied by the Chinese team, fossils such as Castorocauda, a fish-eating, swimming Docodont described back in 2006, provide strong evidence that early mammals adapted to a very wide range of environments.

The Phylogenetic Relationship Between Docodonts, Early Mammals and Extant Mammalia

Examining the phylogeny of early mammaliaforms.

Examining the phylogeny of early mammaliaforms.

Picture Credit: University of Chicago (illustration by April Neander)

Although not closely related to modern placental mammals such as our own species, the Docodonts are revealing themselves to have been a highly successful and very adaptable group of warm-blooded creatures.  It is the mammalian trait of being very adaptable that many scientists believe was key to them becoming the dominant megafauna after the demise of the Dinosauria, Pterosauria and marine reptiles.  It seems this adaptability runs deep in the mammal family tree.

Everything Dinosaur acknowledges the help of the University of Chicago in the compilation of this article.

To read another article that explores the diverse fauna of the Middle Jurassic strata of China: The Amazing and Diverse Daohugou Biota

Fossil Hunting Down Under

Local Fossil Hunters Get the Chance to Work with Professionals

On Sunday 22nd February amateur fossil hunters will get the chance to visit one of the state of Victoria’s most important fossil sites and get advice from leading palaeontologists.  Museum Victoria is holding a special event at the historic Beaumaris Bay fossil site.  The sandstone cliffs preserve evidence of marine fauna from Australia’s prehistoric past.  Many types of shark teeth have been discovered along with the fossilised bones of a number of marine vertebrates.

The day will involve talks from professional fossil hunters Dr Erich Fitzgerald (Museum Victoria), Professor Tim Flannery and Professor John Buckeridge of RMIT University (Melbourne).  Local amateur fossil hunters will also have the chance to have their finds identified by these experts.

Local Fossil Collectors and Professional Scientists Working Together in Beaumaris Bay

Fossil site has open day.

Fossil site has open day.

Picture Credit: David Hastie/Museum Victoria

Commenting on the special, interactive day dedicated to fossil collecting, Dr Erich Fitzgerald (Senior Curator of Vertebrate Palaeontology, Museum Victoria) stated:

“There is simply no better place to find fossils in Melbourne than Beaumaris.  They have helped us paint a rich portrait of what Victoria was like millions of years ago.  The abundance of fossils of large marine animals, especially sharks and whales, suggests that between 6 and 5 million years ago the coastal waters of Victoria were far richer in nutrients than they are today.”

But fossil hunting is not just for professional scientists, as most professional scientists are happy to admit.  Fossils are being eroded out of the sandstone cliffs all the time and if it was not for the dedicated community of local fossil hunters, many potentially significant finds could be severely abraided by wave action or lost all together before a professional palaeontologist got the chance to explore the area.

Dr. Fitzgerald added:

“In Museum Victoria’s collection there are thousands of stunning fossils from Beaumaris, many collected by enthusiastic members of the public with a keen interest in palaeontology.  The public can provide an extremely valuable insight from their fossil discoveries, which would potentially not have been uncovered otherwise.”

Back in 2012, Everything Dinosaur reported on the discovery of a fossilised leg bone found in the Beaumaris Bay area that was identified as belonging to a new genus of “toothed” marine bird.

To read more about this discovery: Giant “Toothed” Birds Once Soared over Southern Australia

With such a huge country to explore, Everything Dinosaur has predicted on numerous occasions that this continent will provide palaeontologists with a number of new fossil discoveries, even new types of dinosaur.  Members of the public who participate in sensible, careful fossil hunting and who are sensitive to the environment and wish to work within the fossil hunting code can make a huge contribution to the Earth sciences.

Everything Dinosaur acknowledges the support of Museum Victoria in the preparation of this article.

Pliocene/Pleistocene Climate Studies Supports Current Climate Change Models

Analysis of Ancient CO2 Levels Reaffirms Current Climate Change Models

A team of international researchers, including scientists from the universities of Bristol and Southampton have analysed ancient levels of carbon dioxide and used this information to reaffirm current predictions about climate change as made by the Intergovernmental Panel on Climate Change (IPCC).  It may be some consolation to know that a study of ancient climates and their related atmospheric CO2 levels does indeed indicate that our planet is likely to respond as predicted to rising levels of this green house gas.

Two sources of prehistoric data were used, each one helping the scientists to piece together a picture of fluctuating warm and cold periods as the Pliocene Epoch led into the much cooler Pleistocene.  In a scientific paper, published in the journal “Nature”, the research team report on the level of CO2 recorded following a study of ancient marine plankton fossils taken from core samples drilled into the sea floor.  The shells of these microscopic creatures provide information on how the world’s climate fluctuated several times over one million years from around 3.3 million years ago.  This data was then cross referenced using CO2 taken from bubbles of ancient atmosphere trapped in ice drilled from both the North and South Poles.

The IPCC predictions as to how the Earth will respond to rising levels of atmospheric carbon dioxide are verified by this new research.  It was during the Pliocene, that the hominins diversified rapidly and the climate fluctuations, periods of intense cold perhaps lasting as long as 100,000 years interspersed with much warmer phases, may have acted as the spur to help these very early humans to migrate out of Africa and to spread further afield.

Scientists know that the Earth’s climate has fluctuated widely over the last 1.8 million years (start of the Pleistocene Epoch).  Temperature, annual rainfall and carbon dioxide levels have all varied cyclically.  By studying the relationship between climate change and CO2 levels during the generally warmer Pliocene, the researchers have been able to assess the validity of IPCC models which attempt to predict future climate change in response to increasing levels of CO2 gas.

Commenting on the study, co-researcher Dr. Gavin Foster (Southampton University) stated:

“We have shown that the change in Earth’s temperature for a given change in CO2, once the effect of the growth and retreat of the highly reflective continental ice sheets was taken into account, was not only identical during both the cold Pleistocene and the warm Pliocene periods, but was also similar to the understanding recently summarised by the IPCC.”

The implication therefore, is that as the world warms up, as in the Pliocene Epoch, the IPCC range of climate sensitivity is likely to be a suitable measure for predicting and describing the degree of warming we should expect.

Atmospheric levels of carbon dioxide have varied hugely since the Archean and although it is very much lower today than it has been for much of our Earth’s history, use of fossil fuels and deforestation have increased the concentration by as much as 35% over pre Industrial Revolution levels.

A Typical European Interglacial Landscape  (Pleistocene)

A wet and boggy landscape

A wet and boggy landscape – but things are going to get warmer

Picture Credit: Everything Dinosaur

So we now have a model that in all likelihood seems to a reliable predictor for climate change.  The trick now is to alter our behaviour and change as a species so that the worst of the climate change can be avoided.

Given our current record, some hope.

China’s Long-Necked “Dragon” Dinosaur

Could This Jurassic Mamenchisaurid Have Helped Establish Dragon Legends?

A team of researchers from Japan, China and the University of Alberta (Canada), have announced the discovery of a new species of mamenchisaurid dinosaur.  A paper on the sixteen metre long, Middle Jurassic giant is being published in the Journal of Vertebrate Paleontology.  Mamenchisaurids are only known from Asia (majority of fossil finds from central China) and as far as we at Everything Dinosaur are aware, their fossilised remains have been restricted to Lower, Middle and early Late Jurassic aged strata.  These animals, members of the Sauropoda, may represent a radiation of Asian, long-necked dinosaurs when the continent was isolated.  How this group, renowned for their extremely long necks and large front legs are related to other components of the Sauropoda remains unclear.

The fossils of this new dinosaur species were uncovered in 2006, when locals were digging a fish pond near Qijiang City, about twenty miles south of the city of Chongqing in central China, although some vertebrae later ascribed to this species were found in the same area in the late 1990′s.  The dinosaur has been named Qijianglong, the name is pronounced (chee-gee-ang-long) and the name means “dragon of Qijiang”.  The formal, binomial name of this dinosaur that roamed the large, flat floodplains of this part of China some 160 million years ago is Qijianglong guokr.  The trivial or specific name honours the Chinese scientific social network “guokr”, which means nutshell.

New Species of Mamenchisaurid Dinosaur Described

Half the body length of this dinosaur was made up of its neck.

Half the body length of this dinosaur was made up of its neck.

Picture Credit: Lida Xing

The picture above shows an adult Qijianglong being harassed by a pair of allosaurid dinosaurs.  A flock of Pterosaurs disturbed by the presence of the dinosaurs takes to the air in the background.  Most palaeontologists believe that the long forelimbs and extraordinarily long neck of most mamenchisaurids evolved as adaptations to help these dinosaurs specialise in feeding on the tops of trees, parts of the available plant biomass that other dinosaurs could not reach.  The neck of Qijianglong was over eight metres in length, it made up half its total body length.  In comparison, most other Sauropods have necks that represent around one third of their body length.

Significantly, much of the skull of this dinosaur was found in association with the cervical vertebrae.

University of Alberta PhD student Tetsuto Miyashita, one of the co-authors of the scientific paper on this new herbivorous member of the Dinosauria explained:

“It is rare to find a head and neck of a long-necked dinosaur together because the head is so small and easily detached after the animal dies.”

Analysis of those cervical vertebrae (neck bones) showed that unique among known mamenchisaurids, the neck bones of Qijianglong had a great many air sacs in them.  This would have made the neck relatively light despite its great size.  Interlocking finger-like processes in the neck bones suggest that this dinosaur had a very stiff neck that was much more mobile bending vertically than horizontally.  The neck anatomy has been described as being similar to the steel construction and supports seen in a tower crane.

Student Miyashita added:

“Qijianglong shows that long-necked dinosaurs diversified in unique ways in Asia during Jurassic times, something very special was going on in that continent.  Nowhere else we can find dinosaurs with longer necks than those in China.  This new dinosaur tells us that extreme species thrived in isolation from the rest of the world.”

The restored Qijianglong specimen is on display in a local museum in Qijiang City, the palaeontologists involved in this study have speculated on whether the fossilised bones of these huge animals helped inspire Chinese dragon myths.  Ironically, since most Chinese dragons are depicted as long-necked reptiles, then early interpretations of dinosaur fossil material that may have inspired stories of dragons, were not too far off the mark.

Strange Hominin Fossils From China – A New Species?

Hominin Fossils from Northern China Could be a New Species

A new study of fossilised teeth and jaw fragments found in a cave back in 1976, suggests the possibility of an unknown species of human living in northern China between 120,000 and 60,000 years ago.  A paper published in the American Journal of Physical Anthropology concludes that the teeth have similarities with Homo neanderthalensis and the much older hominid species H. erectus.

The research was carried out by a team of scientists from Beijing’s Institute of Vertebrate Palaeontology and Palaeoanthropology in conjunction with anthropologists from the National Research Centre on Human Evolution (Burgos, Spain).  The fossils represent the remains of four individuals and the teeth do not resemble those of modern humans.  Instead, they possess a range of primitive and more derived features, this could indicate a new species, yet to be described or possibly a hybrid hominid, a result of interbreeding between two already described species.  The fossils were found in a cave close to the village of  Xujiayao, Yanggao County in Northern China.  The site is approximately 120 miles west of Beijing.

María Martinón-Torres (National Research Centre on Human Evolution), explained that the research team examined the size and shape of the tooth crowns and their associated root system, the groves, cusps and crests.  These features were then compared to over five thousand fossil teeth representing nearly all the known hominin species.  The features of teeth are diagnostic when it comes to determining species and phylogenetic relationships.

The Xujiayao Fossil Teeth Compared to a Modern Human

The Xujiayao cave teeth (left) are compared to a modern human (right).

The Xujiayao cave teeth (left) are compared to a modern human (right).

Picture Credit: Dr. Martinón-Torres with additional annotation from Everything Dinosaur

Dr. Martinón-Torres, a specialist in ancient hominin dentition stated:

“Teeth are like landscapes in miniature.  Each of those slopes, grooves and valleys define a pattern or combination of features that can be distinctive of a population.”

Although a number of palaeoanthropologists have challenged the team’s results and all agree that more fossil material from ancient Asian hominins is required so that a more complete picture can be built up, this study does raise the possibility that there may have been an as yet, unknown species of human living in northern China as recently as sixty thousand years ago.

Given the size of Asia and its relative remoteness thanks to foreboding geological features such as the Ural mountains and the Himalayas, it is not surprising that isolated pockets of early hominins could have evolved distinct characteristics.  Or indeed, given the harsh environment and tough lives of these ancient humans it is not entirely surprising that interbreeding did occur between closely related species that overlapped territories.  Team members at Everything Dinosaur predict that more hominin fossils will be found in Asia that further complicate the relationships between the various recognised species.

Back in 2012, Everything Dinosaur reported on a study of human fossil remains found in south China that could represent a new species of hominin.  These ancient humans were nicknamed the “Red Deer People” and they lived much more recently than the Xujiayao hominins.  The research was carried out by scientists from the University of New South Wales and one of the researchers involved in this earlier study, Darren Curnoe, supports the idea of the Xujiayao fossils being a separate species.  He stated that although the sample was small, the unique characteristics of the teeth did suggest that a new species had been found.

The Associate Professor commented:

“It strongly suggests the presence of a previously unrecognised species.  There’s little doubt in my mind that these teeth stand out as something unique.”

To read more about the research into China’s “Red Deer People”:  Stone Age Remains from Southern China Might Represent Entirely New Human Species

Most palaeoanthropologists accept that from the Middle to the early Late Pleistocene Epoch, a time interval that spans from about 340,000 years ago to 90,000 years ago, Neanderthals occupied Europe and western Asia.  Anatomically modern humans were present in Africa, but the paucity of fossil material prevents scientists from describing the hominin populations of most of Asia.  Furthermore, the evolutionary interaction between eastern populations of hominins and those from Europe and Africa remains poorly understood.  The Xujiayao teeth sample expands the variability for early Late Pleistocene hominin fossils and also suggest that a primitive early human lineage may have survived into the Late Pleistocene in northern China.

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