Category: Palaeontological articles

Marked Variation in the Body Size of Australopithecus afarensis

Fossil Footprints from Tanzania Shed Light on Marked Body Size Variation in A. afarensis

Newly discovered footprints of early hominins found by researchers from the University of Dar es Salaam in collaboration with Italian colleagues, show marked body size variation in our 3.66 million-year-old ancestors.  Analysis of the footprints hints at a social grouping structure more akin to modern gorillas than to chimpanzees and bonobos.   The impressions were created when a group of ancient bipeds walked across wet volcanic ash, these new prints, showing evidence of two individuals walking together were found within 150 metres of the hominin trace fossils discovered in 1978.  The 1978 fossils were attributed to the species of hominin (a primate more closely related to our species than to a chimpanzee), dubbed Australopithecus afarensis.  These newly described tracks too, have been attributed to this species.  They show two individuals, named S1 and S2 in the study, moving on the same palaeosurface and in the same direction as the three hominins documented in the 1978 discovery.

In the scientific paper published in the journal “eLife”, the researchers report that the specimen referred to as S1 had much larger feet than any other member of this group.  Size estimates for this individual indicate an Australopithecus standing 1.65 metres tall (five feet, five inches tall), not as tall as a modern man (H. sapiens), but around five centimetres taller than the height of the average British woman.

Ancient Footprints May Indicate Marked Body Size Difference in Australopithecus afarensis

Footprints (A. afarensis).

Ancient footprints from a second site in Laetoli (Tanzania).

Picture Credit: Raffaella Pellizzon with additional annotation by Everything Dinosaur

In the photograph above, the footprints can be clearly made out, along with tracks made by a number of other Pliocene animals.  The red arrow in the bottom left hand corner marks the direction of travel of the hominins.

The research team propose that these new tracks when reviewed in conjunction with the 1978 trace fossil discovery, may provide clues as to how this ancient species of early human lived.  The newly discovered prints, including the large prints of S1, might be the tracks of a male walking with a collection of smaller females and their offspring.

An Australopithecus Harem?

Commenting on the implications for social behaviour, lead researcher Professor Giorgio Manzi (University of Roma, Italy) stated:

“This novel evidence, taken as a whole with the previous findings, portrays several early hominins moving as a group through the landscape following a volcanic eruption and subsequent rainfall, but there is more.  The footprints of one of the new individuals are astonishingly larger than anyone else’s in the group, suggesting that he was a large male member of the species.”

A Closer View of the Hominin Tracks

Laetoli fossil footprints.

The prints preserved in volcanic ash suggest a large member of the species.

Picture Credit: Raffaella Pellizzon with additional annotation by Everything Dinosaur

Standing around 1.65 metres tall, makes S1 the largest Australopithecus individual described to date.

Commenting on the significance of this new trackway and its proximity to the other Australopithecus tracks, co-author Jacopo Moggi-Cecchi (University of Florence) said:

“Now that we’ve found a new set of footprints it opens up a completely different window and there could be a number of new possibilities to study what is a photograph in time of the everyday life of this species.”

The finding of a male perhaps walking with several females could mean their social structure was closer to the gorilla-like model than to chimpanzees or to modern humans.  These tracks could be interpreted as a large, dominant male walking with his troop of female mates, a sort of Australopithecus harem.

A Map Showing the Location of the Trackways in Northern Tanzania

A map of the Laetoli area (Tanzania)

The site of the Australopithecus trackways in Tanzania.

Picture Credit: eLife

This new trackway evidence, in combination with a comparative reappraisal of the 1978 footprints has important implications for the Pliocene record of early hominin behaviour and morphology.  The results are consistent with considerable body size variation and, probably a degree of dimorphism between males and females within a single species of bipedal hominin as early as 3.66 million years ago.

A Line Drawing of the Hominin Tracks and Other Associated Features

Line drawing of the fossil trackway.

A line drawing of the Laetoli tracks.

Picture Credit: eLife

The four excavated pits that make up the new trackway evidence are represented above in the line drawing.

Dashed lines indicate uncertain contours. Some of the most interesting tracks are coloured: hominins in orange (heel drags in dark grey), prehistoric horses in dark green (M9), rhinoceros in red (M9), giraffe in light brown (M10), and guinea fowl in blue (M10).  Large roots and the bases of trees are in light green (L8).  The main faults/fractures are indicated by brown lines.  Raindrop impressions occur in the northern part of L8 (dotted areas).

The scientific paper: “New Footprints from Laetoli (Tanzania) Provide Evidence for Marked Body Size Variation in Early Hominins” published in the journal eLife.

Fossilised Bacteria Shed Light on Life Before Oxygen

Ancient African Rocks Provide Evidence of Life Before Oxygen

The fossils of ancient bacteria that existed in deep water environments during the Neoarchean Era some 2.52 billion years ago, have been identified by an international team of researchers.  They don’t represent the oldest known life on our planet, recently, Everything Dinosaur published an article on some new research that postulates that microbial colonies existed on Earth some 3.7 billion years ago*, but these South African fossils may represent the oldest evidence of a bacteria capable of oxidising sulphur (within the Class Gamma Proteobacteria), found to date.

A Highly Magnified Image of a Fossilised Bacteria

Fossilised bacteria.

A view of one of the spherical structures identified as fossil bacteria.

Picture Credit: Andrew Czaja

This discovery is significant as it sheds light on a time in Earth’s history, when, essentially, all the microbial forms that exist today had probably evolved, but the fossil record for their existence is particularly sparse. Writing in the journal of the Geological Society of America, the researchers which include scientists from the University of Cincinnati and the University of Johannesburg, report on large, organic, smooth-walled, spherical microfossils representing organisms that lived in deep water, when our planet’s atmosphere had less than one-thousandth of one percent of the oxygen we have today.

Microscopic Life in the Archean

The research team discovered the microscopic fossils preserved in black chert that had been laid down at the bottom of a deep ocean, in the Griqualand West Basin of the Kaapvaal craton of South Africa (Northern Cape Province).  Geologist Andrew Czaja (University of Cincinnati), explained that this part of South Africa was one of the few places in the world where rocks of this great age were exposed.  The fossils are very significant as they represent bacteria surviving in a very low oxygen environment, the bacteria existed prior to “Great Oxygenation Event”, sometimes referred to as the GOE, a period in Earth’s history from about 2.4 billion to 2.2 billion years ago, when water-borne cyanobacteria (blue-green bacteria), evolved photosynthesis and as a result, oxygen was released into the atmosphere.  More oxygen in our atmosphere helped drive the evolution of complex organisms, eventually leading to the development of multi-cellular life.

Commenting on this research Assistant Professor Andrew Czaja stated:

“These are the oldest reported fossil sulphur bacteria to date and this discovery is helping us reveal a diversity of life and ecosystems that existed just prior to the Great Oxidation Event, a time of major atmospheric evolution.”

Radiometric dating and geochemical isotope analysis suggest that these fossils formed on an ancient seabed more than one hundred metres down.  The bacteria fed on sulphates that probably originated on the early super-continent Vaalbara (a landmass that consisted of parts of Australia and South Africa).  With the fossils having been dated to 2.52 billion years ago, the bacteria were thriving just before the GOE, when shallow water bacteria began creating more oxygen as a by-product of photosynthesis.

Czaja’s fossils show the Neoarchean bacteria in plentiful numbers while living within the muddy sediment of the seabed.  The assistant professor and his co-researchers postulate that these early bacteria were busy ingesting volcanic hydrogen sulphide, the molecule known to give off a rotten egg smell, then emitting sulphate, a gas that has no smell.  This is the same process that goes on today as extant microbes recycle decaying organic matter into minerals and gas.  The team surmise that the ancient oceanic bacteria are likely to have consumed the molecules dissolved from sulphur rich minerals that came from the land rocks associated with Vaalbara or from volcanic rocks on the seabed.

Andrew Czaja Points to the Rock Layer where the Fossil Bacteria was Found

Indicating the layer of rock from which the fossil bacteria was collected.

Andrew Czaja (University of Cincinnati), points to the rock layer from which fossil bacteria was collected.

Picture Credit: Aaron Satkoski

Sizeable Bacteria

These fossils occur mainly as compressed and flattened solitary shapes that resemble a flattened, microscopic beach ball.  They range in size from 20 microns (µm), about half the thickness of a human hair, up to a whopping 265 µm, that’s some very large bacteria, about forty times bigger than a human red blood cell, making the fossils exceptionally large for an example of bacteria.  The research team hypothesis that these ancient bacteria were similar in habit to the modern, equally large-sized bacteria Thiomargarita, which lives in oxygen-poor, deep water environments.

Described as being morphologically similar to Proterozoic and Phanerozoic acritarchs and to certain Archaean fossils interpreted as possible blue-green bacteria (cyanobacteria), these fossils are the oldest reported sulphur processing bacteria described to date.  They reveal that microbial life was diverse as early as 2.5 billion years ago and provide further evidence that organisms can thrive in very low oxygen environments.  This may have implications for astronomers as they search for evidence of life on other planets and moons within our solar system.

Images of the Microstructures (Dark, Round Spots within Ancient Rocks)

Microstructures indicate sulphur oxidising bacteria.

Images of microstructures that have physical characteristics with the remains of spherical bacteria.

Picture Credit: Andrew Czaja

*To read Everything Dinosaur’s recently published article (September 2016), about the possible identification of evidence of microbial colonies in strata some 3.7 billion years old: 3.7 Billion-Year-Old Microbes

The scientific paper: “Sulfur-oxidizing Bacteria prior to the Great Oxidation Event from the 2.52 Ga Gamohaan Formation of South Africa”, published in “Geology” the journal of the Geological Society of America.

Fossil Footprints Hint at Decline of Amphibians

The Rise of Reptiles as the World Dried Up

Places like the “Jurassic Coast” of Dorset, or the beaches that surround Whitby (North Yorkshire), might be synonymous with fossil hunting, but surprisingly, even some of our great cities can lay claim to be at the centre of palaeontological research.  Take the city of Birmingham (West Midlands), for example, not the sort of place that one would immediately associate with fossils (the exception being the amazing Wren’s Nest site to the north-west of Birmingham, Britain’s first national nature reserve for geology).  However, the study of a series of sandstone slabs, excavated from a quarry a few miles to the north of the centre of Birmingham is helping palaeontologists to plot global climate change some 310 million years ago, that led to the demise of amphibians and provided ideal conditions for the evolution and radiation of reptiles.

Birmingham, Like Most of the British Isles was once Covered in a Lush Tropical Carboniferous Rainforest

A carboniferous scene.

By the Carboniferous the insects were already highly diversified and the lush forests and swamps were dominated by Temnospondyls (primitive amphibians).

Picture Credit: Richard Bizley (Bizley Art) for more of Richard Bizley’s artwork visit: Bizley Art

In 1912, schoolteacher and amateur botanist Walter Henry Hardaker presented a paper to the Geological Society of London detailing the discovery of a series of Tetrapod footprints and trackways that he had discovered in a quarry located in the village of Hamstead.  Hamstead, itself has long since been swallowed up in the urbanisation of the area as the city of Birmingham expanded.  The quarry too, has gone covered up as houses, shops and offices were built, after all, the quarry was located just a stone’s throw from Hamstead railway station.

The sandstones became part of the Lapworth Museum of Geology’s fossil collection at the University of Birmingham.  Hardaker, an alumnus of Birmingham University, probably would have been fascinated by the recent research work undertaken by third-year Palaeobiology and Palaeoenvironments MSci student Luke Meade (University of Birmingham) and colleagues as they applied 21st Century analytical techniques to reveal a glimpse of the world when reptiles were beginning to take over from the amphibians as the dominant Tetrapods.

Using funding provided by the Palaeontological Association, the students scanned the twenty or so red sandstone slabs using state-of-the-art photogrammetric technology to provide a three-dimensional analysis of each track.  Colour coding of the images permitted the research team to produce topographic maps showing the individual contours of each specimen.  These three-dimensional images were then compared to other ichnofossils (trace fossils) to identify the types of animals which produced the footprints.

The footprints and tracks provide a remarkable insight into vertebrate life during the Pennsylvanian Epoch of the Late Carboniferous.  These trace fossils were formed as animals crawled over soft mud next to river channels.  A subsequent flood event covered these tracks with sand and helped to preserve snapshots in deep time.  The red sandstone slabs preserve amazing details, not only of the footprints and tracks but also raindrops and cracks in the mud that were formed as the area dried out.

To read an article on Carboniferous fossils from North Wales: Tropical North Wales 300 Million Years Ago

The research on these trace fossils indicates that the most common tracks were formed by amphibians, ranging from just a few centimetres in length (Batrachichnus salamandroides) to more than a metre long Limnopus ichnospecies).  Other types of creature traversed the mud, leaving their tracks, animals such as large Pelycosaurs (synapsids distantly related to modern mammals).  Although the tracks are much less common, their presence indicates that monitor lizard-sized Reptiliomorphs also roamed the swamps and low lying forest that was eventually to become the West Midlands of England.  The three-dimensional models of the footprints that the team were able to recreate, led to the identification of these tracks having been made by the ichnogenus Dimetropus.  Smaller reptilian tracks were identified as having been made by sauropsid reptiles, (Dromopus lacertoides), whose descendants gave rise to the crocodiles, marine reptiles, pterosaurs, dinosaurs and birds.

Limnopus Trace Fossils Used in the Study

Limnopus trace fossils (West Midlands).

Carboniferous footprints from the West Midlands (England) indicate the rise of amniotes.

Picture Credit: University of Birmingham/PeerJ

The photograph above shows a well-defined example of Limnopus isp tracks from the Hamstead quarry.  The top photograph shows a dorsal view of the fossil material, (B) tracks rendered to show relief with an arbitrary scale, whereas, (C) shows tracks rendered to highlight areas of steep gradient, digitally isolating the outline of the tracks to aid genus recognition and cross comparison.

Scale bar = 10 cm.

This ichnofauna associated with the Hamstead trace fossils contrasts with the slightly stratigraphically older, more extensive and better-studied assemblage from Alveley (Shropshire), which is dominated by small amphibians with relatively rare Reptiliomorphs and Dromopus tracks are absent. The presence of Dromopus lacertoides at Hamstead, identified from this new study supports the theory that the world was gradually becoming more arid through the Late Carboniferous and different types of reptile were beginning to flourish.

Batrachichnus salamandroides Tracks Preserved in the Red Sandstone of Hamstead Quarry

Batrachichnus fossil trackway.

Hamstead quarry red sandstone showing trace fossils of the Carboniferous amphibian Batrachichnus.

Picture Credit: University of Birmingham/PeerJ with additional annotation by Everything Dinosaur

In the picture above, tracks made by the amphibian Batrachichnus salamandroides are shown, the red line indicates the direction of travel, the long thin lines are tail drag marks.

As the world become drier, so those animals that did not have such a reliance on water compared to the amphibians would have had a distinct advantage.  The synapsids and the diapsids being amniotes (they lay eggs on land or retain a fertilised egg within the female), would have had a significant evolutionary advantage over the amphibians that relied on returning to water to reproduce.

The scientific paper: A Revision of Tetrapod Footprints from the Late Carboniferous of the West Midlands, UK (PeerJ).

Just When Did the Dinosaurs Dominate the Land?

Ixalerpeton polesinensis and Buriolestes schultzi Co-existed

New fossil evidence suggests that the rise of the Dinosauria was more gradual than previously thought.  Many people’s perception of the dinosaurs is that they are all super-sized monsters, dominating life on land and rapidly out competing the other, more primitive Triassic reptiles.  Scientists writing in the journal “Current Biology” challenge this view, as they describe the discovery in the same rock formation of an early dinosaur and a lagerpetid, a member of a group of animals that are recognised as precursors of dinosaurs.  This is the first time that a dinosaur and a dinosaur precursor have been found together, indicating that true members of the Dinosauria Order and their near relatives co-existed.

The Skull of the Dinosaur (Buriolestes schultzi) in Situ

Buriolestes skull at the dig site.

The skull of the sauropodomorph Buriolestes.

Picture Credit: Cabreira et al

A Sauropodomorph and a Lagerpetid

 A team of researchers including Sergio Furtado Cabreira (Museu de Ciências Naturais, Universidade Luterana do Brasil, Brazil) and Alexander Wilhelm Armin Kellner (Departamento de Geologia e Paleontologia, Museu Nacional-UFRJ, Rio de Janeiro, Brazil) have described two new species of Dinosauromorpha from Upper Triassic rocks in central, eastern Brazil (the Paraná Basin).  The fossil material represents a lagerpetid, which has been named Ixalerpeton polesinensis and a new basal sauropodomorph (Buriolestes schultzi), the remains of these animals were found in the Alemoa Member of the Santa Maria Formation, specifically, within the Hyperodapedon (rhynchosaur) Assemblage Zone which dates from the Carnian faunal stage of the Upper Triassic.  Ixalerpeton has been assigned to the family Lagerpetidae which together with the Dinosauria and other closely related Archosaurs, make up the clade Dinosauromorpha.  B. schultzi has been assigned to the Sauropodomorpha, a clade of lizard-hipped dinosaurs that would evolve into the long-necked giants such as Diplodocus, Apatosaurus and Brachiosaurus.

Line Drawings and Photographs of the Fossilised Remains of the Two New Species of Dinosauromorph

Fossils and drawings of the two Dinosauromorpha.

Line drawing (A) of I. polesinensis and fossilised remains of (B-H) and line drawing (I) of B. schultzi with fossil remains (J-P).

Picture Credit: Current Biology

The lagerpetid (Ixalerpeton) has been described from skull bones including the braincase, vertebrae, one shoulder blade, the left humerus, parts of the pelvis, a thigh bone (femur) and some lower leg bones.  This biped is estimated to have measured around half a metre in length. The larger Buriolestes is estimated to have measured around 1.8 metres long and it has been described from a partial skull, which includes the premaxilla, maxilla and the dentary, a large number of vertebrae including posterior dorsal vertebrae and caudal bones, the left arm, parts of the pelvis and a nearly complete left hind leg.


Ixalerpeton polesinensis – The genus name means “leaping reptile”, whilst the trivial name references São João do Polêsine, the town where the fossils were found.

Buriolestes schultzi – The genus name means “Buriol robber”, a reference to the family name of the land owners and recognises that this dinosaur was most likely carnivorous.  The species/trivial name honours Cesar Schultz (professor of vertebrate palaeontology at the Universidade Federal do Rio Grande do Sul).

A Timeline Showing the Relationship between B. schultzi and I. polesinensis within an Overview of Early Dinosauromorphs

A timeling showing the evolutionary relationships of early dinosauromorphs.

Phylogeny of early dinosauromorphs.

Picture Credit: Current Biology

The research team are confident that further analysis of the Ixalerpeton fossil material will add to our understanding as to how the dinosaurs evolved their anatomical characteristics.  The teeth of Buriolestes indicate that this sauropodomorph, a distant ancestor of the huge herbivorous Sauropods, was actually carnivorous.  This evidence supports the theory that the giant plant-eating dinosaurs such as Diplodocus were descended from small, bipedal, meat-eaters.

A Close View of the Teeth of Buriolestes Indicating that this Dinosaur was a Carnivore

The teeth of Buirolestes

A close view of the teeth of Buriolestes. The highly recurved and serrated teeth indicate that this sauropodomorph was a carnivore.

Picture Credit: Cabreira et al

The Dietary Preferences of Dinosauromorphs

An analysis of the fossil teeth of these newly described Archosaurs has helped scientists to assess the dietary preferences of a range of dinosauromorphs.  This research suggests that the very first dinosaurs were all meat-eaters and over time there was a move towards herbivory and an omnivorous diet within certain groups.

The Dietary Preferences of Dinosauromorphs

The diets of dinosauromorphs.

The dietary preferences of members of the Dinosauromorpha.

Picture Credit: Current Biology

The diagram above shows a cladogram of dinosauromorphs and photographs of their teeth.  The top photograph shows the teeth of the dilophosaurid Theropod Dracovenator (Neotheropoda), a carnivore.  Next comes a picture of the teeth of Buriolestes, assigned to the Sauropodomorpha but regarded as carnivorous by the researchers.  The third photograph features the teeth of Pampadromaeus, which coincidentally, was named by Sergio F. Cabreira, Cesar L. Schultz et al.  This little dinosaur has been assigned to the Sauropodomorpha too, it is also believed to be meat-eater.  The final set of teeth belong to the later sauropodomorph Plateosaurus, that lived some fifteen million years after Buriolestes and Pampadromaeus.  The teeth of Plateosaurus seem to be adapted to a plant-eating diet.

The hypothesis about feeding preferences advocated by the researchers in this paper is shown on the left of the cladogram, with alternative arrangements shown on the right.


green coloured line = herbivory and/or omnivory

black coloured line = unknown or ambiguous

orange = carnivore (faunivory – feeding on other animals)

An Illustration of a Buriolestes Catching a Hyperodapedon whilst a Group of Ixalerpeton Scatter

A Buriolestes and Ixalerpeton illustrated.

A Buriolestes catches a Rhynchosaur whilst a group of Ixalerpeton hunt for lizards and grubs in the undergrowth.

Picture Credit: Oliveira Maurílio

This research lends weight to the hypothesis that dinosaurs evolved in the southern hemisphere and that the Dinosauria were carnivorous in their basal forms, it also supports the idea that lagerpetids and early dinosaurs were contemporaries since the first stages of dinosaur evolution.

The scientific paper: “A Unique Late Triassic Dinosauromorph Assemblage Reveals Dinosaur Ancestral Anatomy and Diet” published in Current Biology.

Rapid Recovery of Patagonian Plant-Insect Associations

Research Suggests Southern Hemisphere a Relatively Safe Haven after End Cretaceous Impact Event

Life in much of the southern hemisphere seems to have recovered more quickly than ecosystems further north after the catastrophic Yucatan Peninsula impact event that marked the end of the Cretaceous.  Furthermore, the southern parts of our planet may have provided a biodiversity refuge after the Cretaceous/Palaeogene mass extinction.  These are the conclusions drawn in a newly published scientific paper written by researchers based in the United States and Argentina.

The scientists, which included graduate student Michael Donovan and his supervisor, Professor Peter Wilf (Department of Geosciences, Pennsylvania State University), examined thousands of fossil leaves preserved in strata that represent the latest stage of the Cretaceous (Maastrichtian) and the earliest part of the Palaeocene (Danian).  The fossils were examined under high magnification to identify traces of insect-feeding damage.  From this data, the team were able to calculate how robust and diverse the ecosystem was at each point in deep time represented by the different stratigraphical layers.

An Analysis of Insect Feeding Damage on Fossil Leaves

Leaf miner damage in a Cretaceous leaf.

Mining in a leaf. Initial serpentine phase packed with frass followed by a dramatic widening into a
blotch phase on leaf and b, close-up
of mine path in a.

Picture Credit: Pennsylvania State University

Insect Damage on Leaves – A Measure of the Health of Terrestrial Food Chains

Biologists and botanists have used the number of plant/insect associations recorded in modern-day terrestrial ecosystems to assess the biodiversity of the food chain.  These same principles can be applied to a study of fossil biota and as such, a study that looks at plant-insect associations across the K/Pg boundary can provide palaeontologists with a more complete understanding of how ecosystems coped and bounced back from a mass extinction event.

In an analysis of 3,646 fossil leaves from the latest Maastrichtian as well as from the Danian faunal stages preserved in strata located in Chubut Province, Patagonia (southern Argentina), the team concluded that it took approximately four million years for plant-insect associations to recover after the extraterrestrial impact event.  Studies of insect-plant associations in strata of similar age but much closer to ground zero (western North America), indicate that it took at least nine million years for these associations to recover.

Insect Damage on Fossil Leaves from the Palaeocene

Fossil leaves showing insect damage.

Insect damage from fossil leaves (Danian faunal stage of the Palaeocene).

Picture Credit: Pennsylvania State University

The picture above shows examples of Palaeocene fossil leaves with insect feeding damage.  In photograph (k), skeletonised leaf tissue as a result of insect feeding is shown and (l) shows a portion of the leaf margin of Dryophyllum australis with feeding evidence along the margin.   This new paper, published in the journal “Nature Ecology and Evolution” supports the emerging hypothesis that the impact of the extraterrestrial impact event on ecosystems was variable, particularly in the southern hemisphere.

In general terms, in areas closer to the impact site, such as in western North America, little evidence has been found to support the idea that many different types of insect survived.  However, ecosystems seem to have recovered much faster in South America.  Studies of microscopic plankton and pollen have also provided evidence that life bounced back more quickly in the southern hemisphere than in the north.  The palaeolatitude of the Chubut Province was around 50 degrees south, such locations may have provided a refuge for biota that could then migrate northwards as conditions improved.

Intriguingly, not all fossil sites in the southern hemisphere show signs of biota refuge status at the K/Pg boundary.  In June of this year, Everything Dinosaur published an article on a study of the Upper Cretaceous rocks and Lower Palaeocene strata exposed on Seymour Island in the Antarctic.  This research indicated that there was a dramatic and rapid extinction event in southernmost marine environments.

To read more about this study: Global Catastrophe Caused End Cretaceous Mass Extinction

Two New Species of British Ichthyosaur Swim into View

Two New Species of Jurassic Ichthyosaur Described After Six Years of Research

Much has been written about the “bone wars”, the rivalry between two distinguished and very eminent pioneering American palaeontologists Charles Othniel Marsh and Edward Drinker Cope as they competed with each other to excavate and describe the fossilised bones of dinosaurs from the western United States.  However, during Georgian and Victorian times in Britain, a race was on between well-to-do landowners to excavate and put on display a myriad of strange antediluvian creatures, the remains of which were being found in quarries and construction sites as the industrial revolution transformed the countryside.

Thanks to some dogged detective work, palaeontologists Dean Lomax (Honorary Scientist at The University of Manchester) and Professor Judy Massare (Brockport College, New York) have identified two new species of Ichthyosaur (fish-lizard), from fossil material excavated more than 150 years ago.  These two, very modern scientists are helping to write a new chapter on the evolution, radiation and diversification of British Ichthyosaurs, a story that links back to the early pioneers of palaeontology.

Palaeontologist Dean Lomax Peruses an Ichthyosaur Specimen

Dean Lomax (palaeontologist) studies Ichthyosaur fossils.

Palaeontologist Dean Lomax with one of the Ichthyosaur specimens from the study, BRSUG 25300, the holotype specimen of Ichthyosaurus larkini.

Picture Credit: University of Manchester

Britain During the Jurassic

For much of the Jurassic, the area now known as the British Isles was covered by a warm, tropical sea.  Scattered across this seascape were a number of small islands, this area superficially resembled the Caribbean of today, but instead of green iguanas, basilisk lizards, wild pigs and capuchin monkeys typical of islands such as Barbados, Puerto Rico and Grenada, the terrestrial landscape back in the Jurassic was dominated by dinosaurs.

For further information on the different types of dinosaur that once thrived on the landmass now known as the British Isles we recommend “Dinosaurs of the British Isles” by Dean Lomax and Nobumichi Tamura, available from Siri Scientific Press: Dinosaurs of the British Isles can be ordered here.  The marine environment was also home to an array of exotic prehistoric animals and amongst the most successful of the Early Jurassic marine reptiles were the Ichthyosaurs, formidable predators that had streamlined bodies similar to those of modern dolphins.

An Illustration of a Typical Ichthyosaurus

"Fish Lizard" Found in Australia

A typical Ichthyosaurus (Fish Lizard).

Picture Credit: Everything Dinosaur

Tracking Down Ichthyosaurs

Many of the specimens excavated by early palaeontology pioneers on behalf of wealthy landowners and benefactors were poorly documented, several specimens have become lost, whilst a significant proportion have not been studied fully.  Dean and Judy set about tracking down examples of British Ichthyosaurs, no mean feat as over the years, many fossils had been acquired by museums from all over the world  and a considerable amount of Ichthyosaur material that originated from the British Isles is housed in Europe and elsewhere.  After six years of research, examining hundreds of fossils from all over the UK, Europe and North America, the intrepid pair have been able to identify two new species of British marine reptile.

Analysing Anatomical Features – Hiding in Plain Sight

By analysing features in the skull and post-cranial material, the scientists were able to identify a new species of Ichthyosaurus from a specimen at the University of Bristol.  This almost complete skeleton, had been on public display in the School of Earth Sciences for many years and thanks to Dean and Judy, this specimen has been identified as a new species of Early Jurassic Ichthyosaur.  The animal has been named Ichthyosaurus larkini. The species honours British palaeontologist Nigel Larkin.  The name ‘Larkin’ means “fierce”, which is quite fitting for what was a fast moving, nektonic predator!

Commenting on the outcome of this research, Dean Lomax stated:

“It’s quite amazing, hundreds of people must walk past this skeleton every day, yet its secrets have only just been uncovered.  This specimen has received little in the way of scientific study, although this is not uncommon as there is so much material to see and only a finite amount of funding to see and study everything – in fact, much of my research is self-funded”.

A View of the Holotype Specimen of Ichthyosaurus larkini

Ichthyosaurus larkini.

The holotype specimen of I.larkini.

Picture Credit: University of Manchester

The Second Species – Ichthyosaurus somersetensis

The second new species to be described, making a total of six species within the Ichthyosaurus genus, has an equally interesting story.  The key specimen was probably collected from a quarry in Glastonbury, Somerset, sometime in the 1840’s.   It was sent to Delaware in the United States by Edward Wilson of Tenby, South Wales, for his brother, Dr. Thomas Wilson, who donated the specimen to Philadelphia’s Academy of Natural Sciences in 1847.  The fossil has remained within the Academy’s vertebrate fossil collection ever since.  It was kept in storage and few people knew that it even existed.

Dean explained:

“In my opinion, this specimen is the best example of Ichthyosaurus collected to date.  It paints such a cool picture too, having been found in a quarry in the Somerset countryside, cleaned, and then sent by boat to Philadelphia, and only now for it to be rediscovered – it’s like a good mystery book, piecing the story together!”

As so many Ichthyosaurus specimens have been found in Somerset, it was decided to honour the south-west of England county by naming the new species Ichthyosaurus somersetensis.

The Holotype Specimen of Ichthyosaurus somersetensis

Ichthyosaurus somersetensis holotype.

ANSP 15766, holotype specimen of Ichthyosaurus somersetensis.

Picture Credit: E. Daeschler Academy of Sciences of Drexel University.

The picture above shows the holotype specimen of Ichthyosaurus somersetensis a practically complete skeleton lying on its right side; from Glastonbury, near Street, Somerset, the white scale bar represents 10 cm.

As part of their extensive search, Dean and Judy were keen to visit collections that were not known for their marine reptile fossils, which meant other scientists may not have visited them previously.  All examples of the new species come from locations that can no longer be accessed, for example, old quarries.

Dean concluded by saying:

“It is our hope that other similar fossils will be rediscovered in uninspected collections and brought to the attention of palaeontologists.  Who knows what else is waiting to be (re)discovered?” 

To read an article about the naming of a new species of marine reptile to honour Mary Anning: New Species of Ichthyosaurus honours Mary Anning

The Paper (published in Palaeontology): Two New Species of Ichthyosaurus from the Lowermost Jurassic (Hettangian) of Somerset, England by Dean R. Lomax and Judy A. Massare.

Countdown to TetZooCon 2016

Countdown to TetZooCon 2016

The countdown has started, Tetrapods from all walks of life will be getting ready for the third annual TetZooCon gathering this Saturday (1st October).  The great and the good in the TetZoo-verse will be making their way to the London Wetland Centre (Barnes, London, SW13) to enjoy a series of presentations from illustrious speakers covering topics as wide ranging as British reptiles and amphibians, palaeoart, pterosaurs and sea monsters.  Highlights this year include John Hutchinson providing an insight into locomotion and biomechanics, specifically kneecaps, expect some jumbo sized explanations as pachyderms get placed up front and centre!  Look out also for Hannah O’Regan’s (University of Nottingham), talk on the Ursidae in the archaeological record could TetZooCon be turning into a teddy’s bear picnic?  Certainly, organisers Darren Naish, John Conway and friends have ensured that tea and coffee is included in the admission price of £50 and attendees can pick up lunch and other snacks at the London Wetland Centre in between the cornucopia of events, activities and speakers that have been assembled.

Countdown to TetZooCon 2016

TetZooCon 1st October 2016.

TetZooCon banner 2016.

Picture Credit: Darren Naish

For further information on this event and for last minute ticket information check out this link: TetZooCon 2016

Palaeoart, Plushies and Publications

TetZooCon gives fans of biology, zoology, palaeontology, cryptozoology, conservation and how animals (living and extinct) are portrayed in art, literature and fiction the opportunity to meet up once a year and to indulge their interest in all things related to the Tetrapoda and the contents of the world-famous blog Tetrapod Zoology (currently hosted by Scientific American and followed by Everything Dinosaur team members).  On the subject of blog writers followed by Everything Dinosaur, renowned flying reptile expert Mark Witton (he of Mark Witton’s blog), will be attending and conference delegates will be able to purchase signed prints of his artwork as well as copies of his new book “Recreating an Age of Reptiles”.  Over the course of the day visitors will be able to peruse and purchase a range of merchandise including spectacular illustrations and to get their hands on some of the very latest publications.  Rumour has it that the recently refurbished lecture theatre at the London Wetland Centre will see the unveiling of the new dinosaur book “Dinosaurs: How They Lived and Evolved” by Darren Naish, only a limited number of copies of this highly anticipated new volume will be available, doors open promptly at 9am with the first presentation scheduled to start at 9.20am, best to get there early to avoid disappointment.

The TetZooCon Quiz

Just prior to the traditional end of event trip to the local hostelry and bringing down the curtain on the day-long activities there is the quiz and look out for some fantastic prehistoric animal scale replica prizes provided by Everything Dinosaur who are once again proud to be involved in such a worthwhile event.

Up for Grabs a “Winston” Rebor Replica and Other Prizes

Rebor Velociraptor "Winston"

Rebor 1:18 scale Velociraptor model

Picture Credit: Everything Dinosaur

We wish all the delegates and speakers a wonderful day!  Perhaps next year it will be a two day event, now that’s a thought!

Look Out for Everything Dinosaur at TetZooCon 2016

Everything Dinosaur at TetZooCon

All ready for the TetZooCon 2016

Picture Credit: Everything Dinosaur

Fishing Ankylosaurs?

Liaoningosaurus paradoxus Lives Up To Its Name

With the description of a new specimen of the armoured dinosaur Liaoningosaurus having being published, rather than cementing what scientists knew about this Early Cretaceous dinosaur, it seems that palaeontologists are perhaps going to have to re-think this particular member of the bird-hipped dinosaurs, tentatively assigned to the Ankylosauridae.  A number of fish skeletons were preserved in association with the fossilised bones and teeth of this little critter, this has, along with an assessment of the shape of some of these bones and an examination of the very peculiar teeth, led to the authors of the paper speculating that Liaoningosaurus was a fish-eater.  A sort of armoured dinosaur that thought it was a freshwater turtle.

Did Liaoningosaurus Eat Fish?

Liaoningosaurus a fish-eating armoured dinosaur.

A newly discovered specimen of Liaoningosaurus indicates that these small armoured dinosaurs may have eaten fish.

Picture Credit: Ji et al

A Paradoxical Dinosaur – Divides Opinion

The scientists publishing in the “Journal of Geology” postulate that Liaoningosaurus paradoxus is not only one of the smallest bird-hipped dinosaurs (Ornithischians) so far described, but it might represent the first carnivorous member of the Ornithischia too.  To understand a little more about this dinosaur we have to return to the beginning, way back to 2001 when this dinosaur was formally named and described after the near complete fossilised remains of an individual armoured dinosaur were found in deposits that form the famous Yixian Formation of Liaoning, north-eastern China.  The fossils were thought to represent a juvenile and as such, with quite a bit of growing to do (it was presumed), the researchers noted its distinct anatomical features but put them down to the fact that many of these traits would be modified as the animal grew into maturity.  After all, the body-plan of an armoured dinosaur was quite well known and why should this 34 centimetre-long specimen deviate from that plan to any great extent?

Typical Late Cretaceous Ankylosaurs – (Saichania and Ankylosaurus)

Models of armoured dinosaurs.

Armoured dinosaur models.

Picture Credit: Everything Dinosaur

One of the stranger features identified in the original 2001 paper was that Liaoningosaurus seemed to possess a large, bony plate, described at the time as being “somewhat shell-like” that shielded the abdomen.  This “belly-plate” was reminiscent of the plastron found in turtles.  This was the first time that any such structure had been reported on from any member of the Dinosauria.  In 2014, a reassessment of the fossil material led by ankylosaurid specialist Victoria Arbour concluded that these structures were more likely to represent fossilised skin.

A Line Drawing of the Holotype Fossil of Liaoningosaurus and a Close up of the “Belly Plate” (IVPP V12566)

Liaoningosaurus fossil drawing.

A line drawing of the very “turtle-like” holotype of the armoured dinosaur Liaoningosaurus.

Picture Credit: Arbour et al (2014)

The picture above shows a line drawing of the first Liaoningosaurus fossil to be described (A) with a close up of the skin which was thought to be some sort of protective plate on the abdomen (B).  The scale bar equals five centimetres and the dinosaur does resemble a turtle in shape to some extent.

Fossilised Fish Inside the Body Cavity

The co-authors of the new scientific paper cite the presence of numerous fish fossils inside the body cavity of the Liaoningosaurus as evidence that suggests that this armoured dinosaur might have been a piscivore (fish-eater).  Up until now, it was thought that armoured dinosaurs such as the ankylosaurids were entirely herbivorous.

The Remains of Freshwater Fish Found in Association with the Body Cavity of Liaoningosaurus

Liaoningosaurus bones with fish remains in the body cavity.

The newly described Liaoningosaurus suggests that these armoured dinosaurs may have eaten fish.

Picture Credit: Ji et al

In the photograph above the orange marks indicate the location of fish fossils.

The scientists are quick to state that this evidence is not conclusive.  Three ways in which the fish could have been preserved with the dinosaur are considered:

  1. Could the fish have been sheltering inside the sunken corpse of the dead dinosaur or perhaps scavenging it when they themselves were overtaken by some catastrophic event and died?
  2. The corpse of the Liaoningosaurus could simply have to come to rest on the bottom of the body of water that coincidentally also had a number of dead fish lying on the sediment where it landed.
  3. Liaoningosaurus was a very specialised form of armoured dinosaur, one that was either fully or semi-aquatic and it fed on fish.

Of the three explanations, it is the latter, the piscivore hypothesis, that is favoured by the authors.  After all, this is not the first case in the Kingdom Animalia of one type of animal adopting a very different lifestyle compared to its near relatives.  Take the nocturnal and retiring Pangolin (Order Pholidota), for example.  These mammals are the only members of the Mammalia to have evolved large, protective keratin scales over their bodies, ironically superficially similar to the bony osteoderms and scutes of armoured dinosaurs.  Pangolins are insectivores, but their nearest relatives the Carnivora are almost all meat-eaters preying on other vertebrates.

Long Limbs and Forked Teeth

Both scientific papers allude to the fact that this small dinosaur, a little over thirty centimetres in length, had a number of peculiar anatomical features.  The long lower limbs, sharp claws and elongated feet could be traits that reflect the immaturity of the individuals but they also could be adaptations for a swimming habit – could Liaoningosaurus be the first carnivorous Ornithischian dinosaur to be described?

Those teeth, oversized for an ankylosaurid and their strange crowns could be adaptations for catching and eating slippery fish.  There are teeth present in the premaxilla, once thought to be a characteristic of a juvenile ankylosaurid that was lost as the animal grew up.  Teeth in the front of the mouth make sense if you are catching fish for a living.  The finger-like, forked crowns are highly modified, they would have made short work of any fish to get within grabbing distance of those powerful jaws.

Photographs of the New Specimen of Liaoningosaurus and Close Up Views of Three Maxillary Teeth (with Line Drawing)

Fossils of a fish-eating armoured dinosaur described.

(a) positive dorsal view, (b) negative counterpart of specimen with (c) three maxilla teeth in lateral view and (d) a line drawing showing the forked crowns – an adaptation for eating fish?

Picture Credit: Ji et al

The photograph above shows the positive slab and the counter slab (the negative) of the fossil.  In the bottom left corner there is a close up of three teeth, to the right a line drawing showing the peculiar forked pattern of the tooth crowns.

When first described, this little dinosaur was given the trivial name “paradoxus” a reference to the paradox the fossil represented.  It could not be decided where in the Ankylosauria clade Liaoningosaurus should be placed, paradoxically, despite the finding of a second beautifully preserved specimen, scientists still have lots of questions to explore when it comes to the smallest armoured dinosaur described to date.

This is one dinosaur that certainly lives up to its name.

Reference: Ji, Q., Wu, X., Cheng, Y., Ten, F., Wang, X., Ji, Y. “Fish hunting Ankylosaurs (Dinosauria, Ornithischia) from the Cretaceous of China”. Journal of Geology. doi: 10.3969 /j.issn.1674-3636.2016.02.183

Chinese Fossil Primates Unravel Evolutionary Puzzle

Ancient Asian Primates Decimated by Climate Change

The lineage of primates that led to the monkeys, the apes and eventually the hominins (that’s us), originated in Asia.  Palaeoanthropologists and palaeontologists tend to agree on this as the known fossil record suggests a Far Eastern evolutionary heritage for our distant ancestors.  However, there is a conundrum, if the anthropoids (those flat-faced monkeys that led to the apes and ourselves), evolved in Asia, then why didn’t this evolutionary line continue and lead to higher apes and hominins from Asia?

The fossil record indicates that the earliest anthropoid fossils date from 45 million years ago (Asian fossil discoveries).  In African strata some seven or eight million years younger, the first fossils of African anthropoids are found.  We can conclude from this fossil evidence that the anthropoids first evolved in Asia, only making their way to Africa around 38 million years ago, with the hominins evolving something like 33 million years later, but only in Africa, so what caused the Asian anthropoids to stall?

Thanks to some remarkable fossil finds from China, scientists have solved this primate puzzle, it seems that dramatic climate change some 34 million years ago, nearly wiped out Asian primates, decimated populations and rendered much of that continent as “no go” areas for our distant cousins.

Ancient Teeth and Bones Provide an Important Breakthrough in Our Understanding of Primate Evolution

Fossil jaws and teeth of ancient Chinese primates.

Different types of ancient primate from southern China identified from their fossilised jaws and teeth.

Picture Credit: Chinese Academy of Sciences

The picture above shows the different types of fossil teeth and jawbone used by the scientists to identify new species of Asian Oligocene primates.

In a study published in the journal “Science”, researchers from the University of Kansas in collaboration with colleagues from the Chinese Academy of Sciences, report on the identification of six new species of primates from a site in southern China.  Described as a “mother lode”, these extremely rare and precious fossils shed light on how some Asian primates survived the global cooling event that marked the end of the Eocene Epoch.

Eocene to Oligocene Transition (EOT)

The end of the Eocene Epoch is marked by a significant extinction event.  It may not have been as devastating as the end Cretaceous extinction that led to the demise of something like 70% of all large terrestrial animals, but nonetheless, there was a considerable amount of faunal turnover with many long-established genera (such as the early whales), becoming extinct.  Some 34 million years ago, the Earth cooled dramatically.  Global temperatures fell from an average of around 21 degrees Celsius to around 16 degrees Celsius.  Scientists remain uncertain as to the cause of the cooling, although there was considerable tectonic plate activity, volcanism and a number of extraterrestrial impacts during the Late Eocene.  Some studies have indicated a fall in atmospheric carbon dioxide at this time.  This “greenhouse gas”, so feared today, because of its affect on global warming, may have been reduced in the atmosphere to such an extent that the Earth entered a phase of dramatic cooling.  It is at this time that Antarctica began to change into the frozen wasteland we know today.

As the Earth grew colder so the tropical forests shrank and the available habitat for Asian primates was greatly reduced, the six newly described species were part of an ecosystem that clung on in southern China, an area where a tropical climate still persisted.

Commenting on the significance of this decade long study, co-author of the scientific paper, K. Christopher Beard, (senior curator at the University of Kansas Biodiversity Institute) stated:

“Primates like it warm and wet, so they faced hard times around the world — to the extent that they went extinct in North America and Europe.  Of course, primates somehow survived in Africa and southern Asia, because we’re still around to talk about it.”

The Key to Understanding the Evolution of Primates

As anthropoid primates first appeared in Asia, these new fossil discoveries help scientists to understand the fate of primates on that continent, which is fundamental to understanding early primate and ultimately ape evolution.

Senior curator Beard added:

“This has always been an enigma.  We had a lot of evidence previously that the earliest anthropoids originated in Asia.  At some point, later in the Eocene, these Asian anthropoids got to Africa and started to diversify there.  At some point, the geographic focal point of anthropoid evolution — monkeys, apes and humans — shifted from Asia to Africa.  But we never understood when and why.  Now, we know.  The Eocene-Oligocene climate crisis virtually wiped out Asian anthropoids, so the only place they could evolve to become later monkeys, apes and humans was Africa.”

Working with colleagues from the Chinese Academy of Sciences (Institute of Vertebrate Palaeontology and Palaeoanthropology), specifically Xijun Ni, Qiang Li and Lüzhou Li, the researchers were able to shift through the 34 million-year-old sediments to find teeth and jaw fragments that enabled them to erect six new species.  The fossils were recovered from the upper part of the Caijiachong Formation, Yuezhou Basin, Yunnan Province, through a combination of careful site mapping and scree washing.  It seems that whilst much of Asia became inhospitable for primates, this part of China retained tropical forest so a number of species ended up being crowded into a limited space.

A List of the Six New Species of Primate Named

  1. Yunnanadapis folivorus (pronounced You-nan-ah-dap-is) a member of the Strepsirrhini (lemurs).  In the fossil teeth photograph above Y. folivorus is A.
  2. Yunnanadapis imperator (pronounced You-nan-ah-dap-is) a member of the Strepsirrhini (lemurs).  In the fossil teeth photograph above Y.  imperator is B.
  3. Laomaki yunnanensis (pronounced Lay-oh-ma-key) a lemur-like primate (Strepsirrhini).  In the photograph of the fossil teeth above L. yunnanensis is C.
  4. Gatanthropus micros (pronounced Gat-anthro-pos) another lemur-like primate.  In the fossil teeth picture above G. micros is D.
  5. Oligotarsius rarus (pronounced Olee-go-tar-see-us) the only member of the Tarsiidae (Tarsiers) described from this location.  O. rarus is represented by E in the fossil teeth picture above.
  6. Bahinia banyueae (pronounced Ba-hin-nee-ah), the only anthropoid identified, superficially similar to today’s marmosets, represented by F in the fossil teeth photograph above.

Differences in Oligocene Primate Faunas

The team’s research suggests that the Eocene-Oligocene transition (EOT) led to completely different primate faunas in Asia compared to Africa and the Near East.  In Africa, the anthropoid primates radiated, diversified and became dominant.  However, in Asia, it was the lemur-like primates the Strepsirrhini that seem to have dominated.  The EOT acted as an evolutionary filter dramatically altering the evolution of primates around the world.

The EOT Acted as an Evolutionary Filter Changing Primate Evolution

Global cooling changed primate evolution.

Changing Primate Faunas due to Eocene to Oligocene transition.

Picture Credit: Chinese Academy of Sciences

The EOT changed the evolutionary history of the primates, acting as a filter.  When the composition of early Oligocene primate faunas of Asia and Afro-Arabia are compared, we see that in Asia it was the lemur-like primates (Strepsirrhini) that rose to dominance, whereas in Afro-Arabia, the lemurs became much rarer and it was the anthropoid apes that diversified and became prominent.

The Rare Oligotarsius

Tarsier fossils are incredibly rare in the fossil record, and very little is known about the evolution of the Tarsiidae, the trivial name of O. rarus recognises this.  The teeth of Oligotarsius are very similar to modern tarsiers found today in Indonesia and the Philippines.  This suggests that extant tarsiers are little changed from their ancient ancestors.

Tarsiers – A “Living Fossil”

An extant tarsier.

A photograph of a modern tarsier, described as a “living fossil”.

Picture Credit: University of Kansas/Andrew Cunningham

Dr. Beard explained:

“If you look back at the fossil record, we know that tarsiers once lived on mainland Asia, as far north as central China.  The fossil teeth described in this paper are nearly identical to those of modern tarsiers.  Research shows that modern tarsiers are pretty much living fossils, those things have been doing what they do ever since time immemorial, as far as we can tell.”

A Vulnerability of All Primates?

This new study underscores a vulnerability of perhaps, all primates, that is how they cope when there is dramatic climate change.  The global cooling of the EOT altered primate evolution and transformed the primate faunal mixes of both Asia and Africa.  The EOT is an opposite climate effect to what we are experiencing today.  Thirty-four million years ago the world cooled, today people are very concerned about global warming, the key point is this, whether the climate warms or grows cold, primates seem to be more sensitive to a changing world than other mammals.  This could mean very bad news for our own species.

Food for Thought

It is a sobering thought, but what if the Eocene-Oligocene cooling had not taken place?  Asian anthropoids would have continued to evolve and diversify, potentially with far-reaching consequences for all primates, including hominins and our own species.  Homo sapiens (that’s us), evolved in Africa some 220,000 years ago, however, had this ancient cooling not occurred, the outcome in terms of anthropoid and ultimately human evolution could have been very different.

For an article on potentially the oldest primate: The Oldest Primate To Date?

To read about Miocene Tarsiers from Thailand: Miocene Tarsier Fossils from Thailand

World’s First Mass Extinction Engineered by Animals

Ediacaran Faunal Out Competed by Newly Evolved Animals

A remote fossil site in Namibia has helped strengthen the theory that the fauna of the Ediacaran was unable to survive the radical “re-engineering of marine ecosystems” that resulted with the evolution of more advanced biological organisms.  Newly evolved metazoans (animals that have three types of tissue layer in the embryo and are multi-cellular), altered the marine environment so much that most of the older, largely immobile, species that had dominated the Ediacaran geological period died out.

A Late Precambrian (Ediacaran) Marine Environment

Ediacaran marine life.

Life in the Ediacaran.

Picture Credit: John Sibbick

The Ediacaran geological period is defined as the last geological period of the Proterozoic (early life), it lasted from around 635 million years ago to 542 million years ago and this geological period saw the emergence of a diverse variety of soft-bodied multi-cellular creatures, most of which have no living descendants today.  The ecosystems that existed were very simple with short food chains, multi-cellular life was bizarre with many organisms shaped like discs, tubes or fronds.

Towards the end the Ediacaran more advanced and crucially mobile organisms began to evolve.  Food chains became more complicated with the evolution of active predation amongst organisms.  These new species were “ecological engineers” who changed the environment in ways that made it more and more difficult for Ediacaran organisms to survive.  That is the conclusion of the research team which studied the Namibian fossil remains.

Assistant Professor Simon Darroch Searching the Namibian Site for Fossils

Fossil hunting (Namibia)

Searching for fossils dating from the Ediacaran (southern Namibia).

Picture Credit: Sarah Tweedt, Smithsonian Institution

Writing in the journal “Palaeogeography, Palaeoclimatology, Palaeoecology”, the scientists, which include Simon Darroch (Assistant Professor of Earth and Environmental Sciences at Vanderbilt University located at Nashville Tennessee), report that they have found one of the best-preserved examples of a mixed community of Ediacaran and metazoan organisms preserved in strata from the Zaris sub-basin of southern Namibia.

The Biota Replacement Model

Palaeontologists had predicted that evidence would be found in the fossil record to indicate ecosystems dominated by Ediacaran organisms being replaced by ecosystems dominated by organisms whose fossil record persist into the Cambrian and beyond.  The Namibian fossils provide the best evidence yet of a close ecological association between these distinct types of life-form.

Assistant Professor Darroch explained:

“Until this, the evidence for an overlapping ecological association between metazoans and soft-bodied Ediacaran organisms was limited.  Here, we describe new fossil localities from southern Namibia that preserve soft-bodied Ediacara biota, enigmatic tubular organisms thought to represent metazoans and vertically oriented metazoan trace fossils.  Although the precise identity of the trace makers remains elusive, the structures bear several striking similarities with a cone-shaped organism called Conichnus that has been found in the Cambrian period.”

Conichnus Trace Fossils from Namibia – Evidence of Biota Replacement

Conichnus trace fossils (Namibia).

Conichnus burrows are trace fossils. The surface bumps represent vertical tubes that were originally occupied by anemone-like animals that may have fed on Ediacaran larvae

Picture Credit: Vanderbilt University/Darroch

Conichnus is an ichnogenus (known only from trace fossils), that may have been some form of anemone that fed on Ediacaran larvae.  The scientists also report that they have found strands of Ediacaran frond-like organisms with animal fossils preserved in place coiled around their holdfasts.  The Namibian fossil material provides a snapshot of a transitional ecosystem prior to the Cambrian explosion which led to the evolution of much more modern looking food chains.

Assistant Professor Darroch stated:

“Both animal burrows – ‘trace fossils’ – and the remains of animals themselves sharing the same communities, lets us speculate about how these two very different groups of organisms interacted.”

Lessons for Today

Although the research team are studying the remains of organisms preserved in rocks that were laid down more than 540 million years ago, the biota replacement model that these fossils seem to confirm has relevance for our planet today.  Some of the fossil strata shows the preserved body fossils of a bizarre metazoan called Shaanxilithes, these fossils are coiled found the anchoring, trace fossil (a holdfast) of a frond-like organism),

Shaanxilithes Fossils (Ediacaran Strata – Namibia)

Signs of Late Ediacaran biota replacement.

Shaanxilithes are odd, annulated and ribbon-like fossils that start showing up near the end of the Ediacaran period. In this fossil they are wrapped around Aspidella holdfasts.

Picture Credit: Vanderbilt University/Darroch

Simon explained:

“There is a powerful analogy between the Earth’s first mass extinction and what is happening today.  The end-Ediacaran extinction shows that the evolution of new behaviours can fundamentally change the entire planet, and today we humans are the most powerful ‘ecosystems engineers’ ever known.”

This research entitled: “A mixed Ediacaran-metazoan assemblage from the Zaris sub-basin, Namibia”, builds on an earlier scientific paper published last year that examined a large number of animal burrows preserved in the Namibia rocks that were interpreted as representing the fossil record of a community under stress.

The Disc-Like Structures Represent the Holdfasts of Ediacaran Organisms

Trace fossils (Aspidella).

The disc-like fossils are the preserved remains of holdfast structures used by the Ediacaran species Aspidella that went extinct about a million years after these individuals died and were preserved.

Picture Credit: Vanderbilt University/Darroch

The picture above shows the preserved remains of several disc-like fossils in the Namibian strata.  These have been interpreted as the holdfast, anchoring structures of the fern-like Aspidella.  Once thought to be an ancestral jellyfish, at the time it was first studied, it was the first Precambrian body fossil to have been formally scientifically described.  These disc shapes are now interpreted as trace fossils, examples of the benthic, immobile fauna of the Ediacaran, that was being replaced by more complex and mobile metazoans.

Stirring up Sediments

Hunting and eating the Ediacaran fauna might not have been the only destructive behaviour of the more complex mobile organisms that represented emerging fauna that would dominate the Cambrian.  The researchers also point out that mobile Cambrian animals would have stirred up nutrients leaving them in suspension above the sea floor, far away from the reach of the benthic Ediacaran life-forms.  In essence, the microbial mats and more complex but ultimately, confined to the sea floor Ediacaran fauna, would have found that nutrients that once always fell to the seabed were now suspended in a new marine ecosystem, effectively placing these nutrients out of reach.

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