Category: Palaeontological articles

Reconstructing the Brains of Ancient Lungfish

Comparing the Brains of Extant Lungfish to their Ancient Relatives

The lungfish might be regarded by some as a “living fossil”, a term that we at Everything Dinosaur prefer not to use, as it implies that a species has remained present in the fossil record for a very long time.  However, the six species of lungfish alive today, do represent an extremely long lineage of fishes, that have remained relatively unaltered since they first evolved back in the Devonian.  How similar extant lungfish are to their ancient counterparts has been determined by a team of researchers from South Australia (Flinders University) and Sweden (Uppsala University) who have used a combination of computerised tomography and computer modelling to map and compare the brains of living lungfish species with fossils dating back some 365 million years.

A Very Ancient Lineage of Fishes – Lungfish

A lungfish from Australia.

A living Australian lungfish (Neoceratodus forsteri).

Picture Credit: Getty Images/Tom McHugh

Ancient Vertebrates

Lungfish belong to the Class Sarcopterygii part of the huge bony fish group of vertebrates, that is most closely related to Tetrapods and that includes our own species H. sapiens.  Today’s lungfish, all six species, are becoming increasingly rare and scientists still do not know a great deal about them, their behaviours and how they are able to survive in extreme environments.  One thing we do know, is that for a fish, they are relatively big brained.  Of course, brain size does not necessarily reflect cognitive function, but lungfish brains tend to occupy about 80 percent of their cranial cavity.  Compare this to the somewhat more sedentary and a close relative of lungfish, the Coelacanth (Latimeria).  Studies of Latimeria have shown that less than 5% of their cranial cavity is occupied by their brains.

Using Technology to “Brain-warp” Lungfish Fossils

Having a cranial cavity which is mostly filled by brain tissue is a trait more associated with mammals than with fish.  Knowing this, scientists can use the endocast of lungfish fossils that have been preserved in three-dimensions to map the brains of these ancient creatures.  That is exactly what the Swedish and Australian researchers did and their paper has been published on line in the open source directory of the Royal Society.

The fossilised remains of a Late Devonian lungfish (Rhinodipterus) excavated from the Gogo Formation of western Australia have been subjected to high resolution computerised tomography and the data has been used to “brain-warp” cranial soft tissues so the brains of long extinct creatures can be constructed.

A Three-dimensional Skull Fossil of the Sarcopterygian Rhinodipterus from the Gogo Formation

A Skull of the Lungfish Rhinodipterus.

A three-dimensional Rhinodipterus skull from the Gogo Formation.

Picture Credit: ABC

The picture above shows a right lateral view of the skull of Rhinodipterus excavated from the famous Gogo Formation .  The three-dimensional preservation of fossils has permitted the cranial research to take place.

Flinders University evolutionary biologist and lead author of the scientific paper, Alice Clement commented:

“These fishy cousins of ours offer a great insight into our ancient ancestors who first crawled out of water and onto land some 370 million years ago.”

The research team used the endocast from a fossil lungfish to form a three-dimensional diagram of the brain and surrounding tissue.  From this, the scientists could develop ideas regarding brain function and phylogeny of the lungfish family as a whole.  An ancient lungfish brain reconstructed in virtual reality is one thing, built in conjunction with the team’s own sophisticated and novel distance mapping software, but it is hoped these techniques can be applied elsewhere in the fossil record.

Mapping the Brains of Lungfish

Brain mapping in Lungfish.

The Queensland Lungfish brain compared to an ancient relative (Rhinodipterus).

Picture Credit: The Royal Society

The picture above shows brain comparisons between an extant Queensland lungfish (Neoceratodus) and the extinct lungfish Rhinodipterus of the Late Devonian.   Colour coded distance map (a) for the relationship between brain and cranial cavity in Neoceratodus, (b) a three-dimensional endocast of Rhinodipterus.  The reconstructed brain of Rhinodipterus (c) presented as a colour coded brain endocast distance map and (d), a spatial overlap of the reconstructed Rhinodipterus brain (grey) with the endocast (pale red).  The reconstructed brain of Rhinodipterus viewed from the top (dorsal view) is diagram (e).

Brains are Difficult Things to Study

The new “brain-warp” method is important because when it comes to ancient anatomy, brains are extremely difficult to study.  Soft tissue such as brains is highly unlikely to fossilise, although brain shape and structure can be inferred if the bones that surround the brain are preserved.  By examining the hollow, a lot of information about brain morphology can be obtained.

Palaeontologist John Long, an expert on the fossils of the Gogo Formation and co-author of the scientific paper commented:

“Animals’ soft tissue usually breaks down, so discovery of a fossilised brain is very rare.”

The Strategic Professor of Palaeontology at Flinders University went onto explain that lungfishes have a very long evolutionary history, first evolving some 410 million years ago and having a peak diversity of about a hundred species during the latter part of the Silurian and through to the Devonian.

Weird Facts about Lungfishes

  • Molecular studies using living lungfishes and the Latimeria genus of Coelacanth have shown that lungfishes are more closely related to Tetrapods than Coelacanths.
  • Six species of lungfish are know, the Queensland lungfish (Neoceratodus forsteri) from Australia, four species from Africa and one species from South America.
  • The South American lungfish (Lepidosiren paradoxa) when first scientifically studied in the mid 1830’s was thought to be a reptile due to its close affinity with Tetrapods.
  • The West African lungfish (Protopterus annectans) can go without food for more than three years.  When this lungfish was scientifically described by Sir Richard Owen, it was placed at first with the Class Amphibia (amphibians).

One in the Eye for Jurassic Mammals

Early Mammals May Have Evolved Night Vision as a Jurassic Survival Strategy

Over the last few days a number of articles have been published detailing the research of scientists from the University of Alberta and the National Eye Institute of the United States who have been studying the light detecting photoreceptors in the retinas of mammals.  It turns out that night-time vision, an ability to see in very low light levels, evolved millions of years ago in early mammals during the Jurassic.  Many of these articles have emphasised the possibility that night vision evolved to help the mammals adjust to a nocturnal lifestyle in order to avoid the dinosaurs that dominated during the day.  However, the real significance of the research might be a unique genetic ability in mammals to transform some types of light receptors in the eye.   This could have huge implications when it comes to restoring sight in people with damaged eyes.

Adapted to a Life in the Dark – Most Mesozoic Mammals

Sabre-Toothed Mammal that lived amongst Dinosaurs

Sabre-Toothed Mammal that lived amongst Dinosaurs.

Picture Credit: Associated Press

Rods and Cones

Mammalian eyes are complex organs.  Light enters the eye through the cornea, passes through the pupil and into the lens, where it is focused and then directed back to photo sensitive cells that line the retina at the back of the eye.  These light sensitive cells covert the light into electrical signals that are carried to the brain by optic nerves and the brain then decodes them and provides vision.  The retina contains two main types of distinctive photoreceptor cells – the rods and cones.  Rods are thinner than the cones and they are distributed differently across the retina, but the chemical process in each that supports the interpretation of light to electrical signals is very similar.

  • Rods – are sensitive to low light levels making then highly suited for night vision.
  • Cones – are less sensitive and not capable of operating effectively in low light but they are much better at being able to pick up broader wavelengths of light across the colour spectrum and therefore they are responsible for colour vision and image resolution in bright light.

Student Phil Oel (University of Alberta) One of the Authors of the Scientific Paper

New insight into mammalian eye evolution.

Helping to work out the photoreceptor layout of the mammalian eye.

Picture Credit: The University of Alberta

When the structure of rods and cones are compared, it would appear that the rods are the more primitive and ancient of the two types of light sensitive cell, but this is not the case.  Researchers have long suspected that the light detecting cone cells came first and the rods evolved later.  In the study of the retinas of mice, the researchers found evidence to support the idea of a cone to rod transition.  They found the vestiges of short-wave cones (those responsible for detecting the shorter wave lengths in the visual light spectrum, the blues and violets), in developing rod photosensitive cells.  This would confirm the idea that had persisted for decades that there was a cone-to-rod transition, that the cones came first.

Co-author of the new study, published in the academic journal “Developmental Cell”, PhD candidate Phil Oel (University of Alberta), stated:

“We found evidence in the mouse that these rods were coming from cones, and thought we’d figured it out at that point.”

Enter the Zebrafish – Fresh Insight

When the scientists looked at zebrafish, a member of the most ancient of all the vertebrate lineages, the fish, they found that there was no evidence for short wave cones having converted into rods.  In zebrafish rods did not show any signs of having developed from cones.

Student Phil Oel, explained:

“When we looked for the same thing in zebrafish, we found no evidence for the same feature, that any rods were ever coming from cones.”

The discovery that mice have the ability to convert some types of cone cell into rods is significant in itself, the lack of this feature in zebrafish has helped the researchers solve a seventy-year-old evolutionary puzzle.

If cones provide colour vision and rods vision in low light, it would be reasonable to assume that diurnal (daytime functioning) animals would have a cone cell dominated retina to provide them with optimal daytime vision.  However, studies of mammalian evolution have shown that mammals have a rod dominated retina, better suited for vision at night or a very low light levels, even with diurnal species like H. sapiens.  In humans we have something like 20 rod cells for every 1 cone cell in our retina.

The “Nocturnal Bottleneck”

Evolutionary biologists have traced the origins of a rod dominated mammalian retina to the Late Jurassic and referred to as the “nocturnal bottleneck theory”.  This theory suggests that many mammalian traits such as excellent hearing, a good sense of smell, a rod cell dominated retina, whiskers and a highly developed sense of touch can be explained by the fact that mammals were confined to the dark, poorly lit undergrowth or to a nocturnal existence, so long as the terrestrial reptiles, most notably the dinosaurs, existed.  It was only with the extinction of the non-avian dinosaurs at the end of the Cretaceous that led to mammals diversifying to occupy diurnal niches in ecosystems.  Even today, the majority of the 8,000 species of mammals on our planet are nocturnal.

Recently, the idea that the mammals were restricted to only a few niches and that they were relatively small has been challenged as new fossil finds suggest that during the Cretaceous the mammals were much more diverse and speciose then previously thought.

To read more about this study: Time to Debunk Mammals Totally Dominated by Dinosaurs Myth

Lead author of the research, Ted Allison, Associate Professor in the Department of Biological Sciences at the University of Alberta commented:

“During the Jurassic period, mammals are diversifying, or about to diversify.  The concept that’s been in the literature for years is that mammals took on a nocturnal habit to survive this period, and escaped the daytime roaming dinosaurs by being more active at night.”

Associate Professor Ted Allison (right) and his PhD student Phil Oel

Scientists providing an insight into mammalian evolution.

PhD student Phil Oel and his supervisor Associate Professor Ted Allison.

Picture Credit: The University of Alberta

Those mammals that were best able to exploit the nocturnal way of life, were the ones that survived, going on to radiate and diversify and eventually, after the dinosaur extinction, replacing the Dinosauria as the dominant terrestrial megafauna.  One intriguing question remained, if the mammals were somehow able to produce extra rod cells to help with night-time vision, then where did they come from?

The Associate Professor explained:

“What we’ve proposed here for the first time is a mechanism for how mammals survived that initial nocturnal stage, how they were able to make many rods and exploit that nighttime adaptation.  This nocturnal bottleneck has been theorised now for some 70-odd years, so it’s a big vision mystery solved.”

The findings not only have important implications for evolutionary biologists, but this new understanding may have clinical applications in the future.  If mammals have a way of converting cone photoreceptors to rod cells then it may be possible to apply this research to help develop ways of restoring vision in humans.

The paper: “Recruitment of Rod Photoreceptors from Short-Wavelength-Sensitive Cones during the Evolution of Nocturnal Vision in Mammals.”

Scientists “Root Out” Oldest Plant Root Cells

Oldest Plant Roots Identified

Scientists from Oxford University and the Departamento de Biología Molecular de Plantas, Instituto de Biotecnología, Universidad Nacional Autónoma de México (Mexico), have identified the oldest known population of plant root cells in a 320 million-year-old fossil.  This study, published as an on line, open access article, highlights the importance of historical collections such as the Oxford University Herbaria, which as part of the University’s Plant Sciences Department, houses an extensive botany collection, with some specimens within the archive over 300 years old.

A Slide Showing Preserved Plant Remains from the Oxford University Herbaria Collection

Carboniferous root structures preserved in a thin slice (slide)

A slide made over 100 years ago preserves evidence of fossilised root structures.

Picture Credit: Oxford University Herbaria

The picture above shows a thin soil slice prepared on a slide over 100 years ago and part of the Oxford University Herbaria collection.  The fossilised soil is estimated to be around 320 million-years-old and shows the cellular anatomy of plants which were growing and decaying in the fossil soil underlying the Carboniferous coal swamp forests.

The scientists have not only revealed the oldest plant root stem cells found to date, the research also marks the first time an actively growing fossilised root has been discovered and it shows that plant root cell division in the past may have been more diverse than today.

Roots and Shoots – Getting to the Root of the Problem

The roots and shoots of plants develop from specialised groups of cells called meristems.  These self renew and produce cells that undergo differentiation.  The organisation of these cells changes when growth stops, so up until this research was published, it was impossible to compare the fossil record with the cellular structure of actively growing meristems.  Using slides from the Oxford University Herbaria that represent thin sections of fossilised soils taken from Carboniferous coal balls, researchers were able to identify the fossilised remains of an actively growing root meristem and examine in detail the stem cells and their structure.  They found that the cellular organisation of the fossilised root tip is unique.  Roots and shoots of ancient plants from the Carboniferous may have grown in a broadly similar way to modern plants such as the angiosperms (flowering plants), but the unique cellular order and structure demonstrates that the meristem growth we find today may only represent a proportion of the root and shoot growth diversity that once existed.  This research indicates that some of the biological processes and systems controlling the root development of plants have now become extinct.

A Highly Magnified Image Showing the Growing Root Apex Assigned to the Species Radix carbonica

The holotype fossil of Radix caronica (growing root).

The dark horseshoe-shaped structure is the root cap protecting the growing root apex as it pushes through the soil.

Picture Credit: Oxford University Herbaria

The structures preserved in the fossil record are similar to those found in extant species, but they are different, they represent a unique cellular arrangement not known in modern plants.

Commenting on the study, one of the authors of the paper, Oxford Plant Sciences PhD student Alexander (Sandy) Hetherington stated:

‘I was examining one of the fossilised soil slides held at the University Herbaria as part of my research into the rooting systems of ancient trees when I noticed a structure that looked like the living root tips we see in plants today.  I began to realise that I was looking at a population of 320 million-year-old plant stem cells preserved as they were growing – and that it was the first time anything like this had ever been found.  It gives us a unique window into how roots developed hundreds of millions of years ago.’

The First Global Tropical Wetland Forests

The fossil soil slides and the root structures they contain are extremely important as they provide a record of our planet’s first global tropical wetland forests.  The Carboniferous swamps and wetlands were to form the extensive coal deposits found in much of the world today, including most of the coal in the United Kingdom, exploitation of which fuelled the industrial revolution.  From a biological point of view, these huge, lycopsid (club mosses), pteridosperm (seed fern) and sphenopsid (horsetails) dominated forests represent the first time deep rooting structures evolved on Earth.  These root systems increased the rate of chemical weathering of the silicate minerals in rocks, a chemical reaction that pulled carbon dioxide out of the atmosphere, leading to a period of global cooling – climate change on a worldwide scale.  Of the 139 slides studied, two root caps were identified.  The first was assigned to a known species Lyginopteris oldhamia, a seed fern (pteridosperm), the second was an unknown species, this has been named Radix carbonica, this translates as “coal root”.

Professor Liam Dolan, (Department Head of Plant Sciences, Oxford University) and lead author of the academic paper, explained:

“These fossils demonstrate how the roots of these ancient plants grew for the first time.  It is startling that something so small could have had such a dramatic effect on the Earth’s climate.  This discovery also shows the importance of collections such as the Oxford University Herbaria, they are so valuable, and we need to maintain them for future generations.”

A Highly Magnified Image Showing the Root Cellular Structure

A close up of the fossilised root structure (Radix carbonica).

Fossilised root structure preserves record of ancient root growth.

Picture Credit: Oxford University Herbaria

From examining the size and number of cells which radiate out from the tip the researchers were able to establish that the root was actively growing at the time it was fossilised.  This makes the finding the first and only discovery to date of the fossilised remains of an actively growing root meristem.

The Root Growth of Radix carbonica is Unique Compared to Living Plant Root Meristems

The schematic diagram below shows the cellular organisation of a typical member of the gymnosperm group (conifers, ginkgos and cycads).  The colours show various major tissue types within the meristem.

Mapping the Evolution of Root Systems

The origin of root evolution in the Plantae.

New study suggests different types of root growth in plants took place in the past.

Picture Credit: Current Biology with additional annotation by Everything Dinosaur

The diagram above shows (A and C) the meristem of a typical gymnosperm, compared with (B and D) the meristem of Radix carbonica.

Yellow = the root cap

Pink = the promeristem (yellow lines in the R. carbonica promeristem indicate the positions of anticlinal cell divisions within the promeristem)

Orange = ground tissue

Blue = epidermis

Green = procambium

A simplified cladogram showing the hypothesised origin of roots based on this new study (E).  The meristems of different types of lycopsids are compared to the evolution of ferns, gymnosperms and the path towards the flowing plants (angiosperms), that evolved later.

Everything Dinosaur acknowledges the help of a press release from the press team at Oxford University in the compilation of this article.

The paper “Unique Cellular Organization in the Oldest Root Meristem”  is published in Current Biology. DOI: 10.1016/j.cub.2016.04.072

Sorting Out Lucy’s Neighbours

Pliocene Hominin Diversity – Neighbours for Lucy

Anthropologists have discovered that the human family tree, that branch of the hominins that led ultimately to our own species H. sapiens, is very complicated.  We might like to think that our own evolution was pre-destined, once the first apes that left the trees and started to walk upright on a regular basis, our big-brained species was bound to come along, but that does not seem to be the case.  For example, scientists have now concluded that there were at least four species of hominin present in Europe and Asia up until relatively recently.  In a new paper, published in the “Proceedings of the National Academy of Sciences”, researchers have reviewed Late and Middle Pliocene hominin fossils and concluded that there were multiple species of early hominins around between 3.8 and 3.3 million years ago.  It seems that “Lucy” the most famous example of Australopithecus afarensis had company – lots of company in fact.

Late Miocene and Pliocene Hominin Chronological Distribution

A number of early hominin species have been identified.

Late Miocene and Pliocene hominin diversity.

Picture Credit: PNAS with additional annotation by Everything Dinosaur

All Early Hominin Fossils Packed into a Suitcase

Four decades ago, the number of early hominin fossils discovered in eastern Africa was very low.  We recall anthropologists joking, but with some degree of truth, that the entire east African hominin fossil record could be packed into a single, large suitcase.  However, recent fossil discoveries have greatly increased the amount of fossil material known and raised the possibility that early hominins in Africa were at least as speciose as later members of the human family tree.

The graph above plots the current recognised species of Late Miocene and Early Pliocene hominin species over the last seven million years or so.  The different coloured columns represent different taxa and the length of each column equates to the approximate length of time that each taxon is known to have existed.  Dotted parts indicate uncertainty in the age of a taxon or the absence of fossils from that particular time span.  Lucy, as a member of the Australopithecines (southern apes), and an A. afarensis represents a species that lived from approximately 3.9 million years ago to around 3 million years ago.  The solid, black line forming a rectangle shape on the timeline around 3.6 million years ago shows the presence of multiple hominin species during the Middle Pliocene.  It seems that Australopithecus afarensis had lots of other hominin species for company.

In the diagram above, the dashed rectangle situated around the 6 million years ago mark, indicates possible hominin diversity as far back as the Late Miocene, if the three earliest named hominin species represent different taxa.

An Update on Pliocene hominin fossils from Africa

The authors of the scientific paper, Dr. Yohannes Haile-Selassie and Dr. Denise Su (The Cleveland Museum of Natural History), in collaboration with their colleague Dr. Stephanie Melillo (Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany), have compiled a detailed review of the current fossil material of early hominins, collating data from fossil discoveries from Ethiopia, Chad and Kenya.  This review demonstrates the complexity of the early hominin evolutionary tree and it raises the intriguing question, how did these early humans relate to each other?  For example, was there niche partitioning taking place?  How did these different species compete for resources?

Lead author of the report, Dr. Yohannes Haile-Selassie (Curator of Physical Anthropology at The Cleveland Museum of Natural History), commented:

“It is now obvious that more than one species of early hominin co-existed during Lucy’s time.  The question now is not whether Australopithecus afarensis, the species to which the famous Lucy belongs, was the only potential human ancestor species that roamed in what is now the Afar region of Ethiopia during the middle Pliocene, but how these species are related to each other and exploited available resources.”

Australopithecus deyiremeda

The idea that a number of Australopithecines co-existed is not new.  Back in 2015, Everything Dinosaur reported on the discovery of Australopithecus deyiremeda by a team of researchers led by Dr. Yohannes Haile-Selassie.  This new species was named after four fragmentary pieces of fossil jaw bone complete with teeth, which represented three individuals had been discovered in the Woranso-Mille area of the Afar region in March 2011.

Dr. Yohannes Haile-Selassie Holds a Cast of the Jaws of Australopithecus deyiremeda

A cast of the jaws of A. deyiremeda.

A cast of the jaws of A. deyiremeda an Australopithecine from northern Ethiopia.

Picture Credit: Laura Dempsey

To read about the Australopithecus deyiremeda research: A New Face to the Human Family Tree

Putting an Evolutionary Foot In It!

The paucity of the fossil record and the highly fragmentary nature of most of the known fossil material makes interpreting the fossil record extremely difficult.  Perhaps the most compelling evidence for the presence of more than one type of early human species in eastern Africa between 3.8 and 3.3 million years ago, was the discovery of a partial foot (the Burtele foot), in the Woranso-Mille region of Afar, the same area where the jaws of A. deyiremeda were discovered.

The Burtele Foot Fossil (Afar Region of Ethiopia)

A partial right foot with an opposable big toe representing an as yet not described species of early human.

Picture Credit: The Cleveland Museum of Natural History/ Dr. Yohannes Haile-Selassie

The specimen (BRT-VP-2/73), is photographed above in the correct anatomical position.  These bones represent the right foot and the bones on the left of the picture are the big toe (hallux).  Researchers have concluded that this digit was opposable, so the foot was also used for grasping.  The foot bones, referred to as the “Burtele foot”,  come from strata that is little younger than the strata where the jaw bone fossils of Australopithecus deyiremeda were found.  However, it is possible that these two species may have co-existed.

The foot represents a species that was contemporaneous with A. afarensis and probably several other early hominin species too.  Assessment of the walking abilities of the creature represented by the Burtele foot, indicates that its locomotion was different from that of A. afarensis, perhaps the foot bones provide evidence to support the idea that a more ancient human-like species, Ardipithecus ramidus persisted much longer than previously thought, or these foot bones could represent an as yet unknown species.

Commenting on the need to continue to explore eastern Africa to help unravel this early human puzzle, Dr. Stephanie Melillo of the Max Planck Institute stated:

“We continue to search for more fossils.  We know a lot about the skeleton of A. afarensis, but for the other Middle Pliocene species, most of the anatomy remains unknown.  Ultimately, larger sample sizes will be the key to sorting out which species are present and how they are related.  This makes every fossil discovery all the more exciting.”

Kulindadromeus Gets Its Coat of Feathers

Reconstructing the Feathered Kulindadromeus zabaikalicus

The remarkable Kulindadromeus (K. zabaikalicus), the earliest known member of the Ornithischia (bird-hipped dinosaurs), to have been feathered has been reconstructed as part of a dinosaur exhibition currently on display in Japan.  The beautifully made, life-size model of this early Middle Jurassic herbivore will provide visitors with an opportunity to see for themselves how some of the Ornithischia evolved into feathered forms.  Kulindadromeus suggests that perhaps, the majority of dinosaurs, not just the Theropods were covered in a coat of feathers.

A Life Size Model of Kulindadromeus zabaikalicus

A scale model of the feathered dinosaur Kulindadromeus.

A 1:1 scale model of Kulindadromeus.

Picture Credit: T. Hubin/RBINS

It was back in the summer of 2014 that Everything Dinosaur reported upon the discovery of an extensive bone-bed that preserved the fossilised remains of a number of specimens of this dinosaur.  The rocks represent strata that was laid down sometime between 175 and 160 million years ago (Middle Jurassic Period).

To read an article by Everything Dinosaur on the discovery of Kulindadromeus: Did All Dinosaurs Have Feathers?

The Kulindadromeus fossil material comes from a site on the banks of the River Olov in the TransBaikal region of Siberia.  Dr. Pascal Godefroit (Royal Belgian Institute of Natural Sciences), one of the scientists responsible for naming this little, one-metre-long dinosaur back in 2014, has commissioned the reconstruction of a life-sized model of this feathered animal along with a replica of its skeleton.

A Model of the Skeleton of Kulindadromeus

A replica of the skeleton of Kulindadromeus.

A model of the Kulindadromeus skeleton

Picture Credit: T. Hubin/RBINS

Kulindadromeus was very probably bipedal and it may have lived in flocks, just like many birds do today, but it was not very closely related to Aves (birds).  It had filamentous structures covering most of its body, including its head, chest and neck.  The more complex feather-like structures were restricted to the upper arms and the top of the legs, an arrangement of feathers found in many fossils of small Theropod dinosaurs excavated from Lower Cretaceous strata in the famous Lioaning Province of China.  The long tail, that made up at least forty percent of the animal’s entire length may have been completely devoid of feathers, just covered in scales, giving this dinosaur a “rat-tailed” appearance.

Kulindadromeus Could Not Fly

Standing around sixty centimetres high a the hips, this fast-running dinosaur could not fly.  Instead, the feathers probably served as insulation to help keep this active, little animal warm.

Visitors Will Get the Chance to Look into the Eyes of Kulindadromeus

A life-size replica of the dinosaur Kulindadromeus from Siberia.

Kulindadromeus life-size replica.

Picture Credit: T. Hubin/RBINS

Fossils of this curious dinosaur were uncovered in a series of field expeditions between 2010 and 2013, one of the leading researchers was Dr. Sofia Sinitsa (Institute of Natural Resources, Ecology and Cryology) from the Siberian city of Chita.  When the discovery of Kulindadromeus was announced, it led to wide speculation that all dinosaurs could have possessed some form of integumental covering.  Currently, Dr.  Maria McNamara of Cork University (Ireland), is working on a study of the microstructure of the animal’s “proto-feathers”.  A scientific paper detailing this research is due to be published soon.

Commenting on the significance of Kulindadromeus, Dr. Godefroit stated:

“It is a big discovery.  It has completely changed our vision of dinosaurs.  The animal had a short snout, long hind legs, short arms and five strong fingers.  It had reptile-like scales on its tail and shins, with short bristles on its head and back.”

Hundreds of Bones Excavated

During the course of the summer expeditions, the joint Belgian-Russian team excavated a vast amount of Kulindadromeus fossil material, as well as insect and plant fossil remains.

Kulindadromeus Fossil Material from the River Olov Site

Preserved Kulindadromeus bones in a volcanic ash deposit.

Kulindadromeus fossil material.

Picture Credit: T. Hubin/RBINS, V. Shevchenko

In the field photograph of one of the fossil slabs from the dig site (above), Kulindadromeus bones can be made out in the bottom right hand corner of the piece of rock.  Danielle Dhouailly, an expert on bird feathers from the Universite Joseph Fourier in La Tronche (France) explained:

“The feathers look like down feathers from some modern chickens.  When we compare them with the leg scales, it looks as if the scales are aborted feathers, an idea that has been suggested to explain why modern birds also have scaly, bare legs.”

The wonderful Kulindadromeus replica is currently being displayed at the Tokyo National Museum of Nature and Sciences.

 Dr. Pascal Godefroit added:

“I was really amazed when I saw this.  We knew that some of the plant-eating Ornithischian dinosaurs had simple bristles and we couldn’t be sure whether these were the same kinds of structures as bird and Theropod feathers.  Our new find clinches it, all dinosaurs had feathers, or at least the potential to sprout feathers.”

The discovery of Kulindadromeus and the identification of feathered Ornithischians raises the tantalising possibility that the common ancestor of both the Theropoda and the Ornithischian dinosaurs, which might have lived more than 235 million years ago, may have been covered in feathers.

Early Cretaceous Crocodile from Brazil Subjected to Shrink Ray

Susisuchus anatoceps – Probably a Dwarf Crocodile

A team of Brazilian based scientists have concluded that the Early Cretaceous crocodile Susisuchus (S. anatoceps) may not have been as large as previously thought, writing in the on line, open access journal PLOS One, the researchers suggest that this species may have grown to less than one metre in length.  It had been thought that specimens collected to date represented juveniles but analysis of growth rings preserved in the fossilised bones of one individual, believed to have died when it was around seventeen years old, suggests that this reptile rarely exceeded seventy centimetres in length.

Early Cretaceous Crocodile Subjected to Palaeontologist Shrink Ray

Susisuchus anatoceps scale drawing.

A modified scale drawing of the Cretaceous crocodile Susisuchus.

Picture Credit: University of Queensland with additional annotation by Everything Dinosaur

Originally described in 2003 from a partial skeleton representing an individual whose desiccated carcase probably laid out on an ancient riverbed for some considerable time before eventual burial, Susisuchus anatoceps is known from about ten fossil specimens, which from their small size were all thought to represent young animals.  However, the scientists, which included lead author of the scientific paper Juliana M. Sayão  from the Universidade Federal de Pernambuco (north-eastern Brazil), analysed the internal structures of a two bones (a rib and a bone from the lower front limb – an ulna) from a Susisuchus and concluded that this specimen represented an animal that was a sub-adult and therefore nearly fully grown.  This research suggests that these crocodiles were small bodied and comparable to extant dwarf crocodiles.

The Fossil Specimen Studied Showing Location Where Bone Samples Were Taken and Close up Views of the Bone Structure

Calculating the age of Susisuchus anatoceps.

A close up of the rib and limb bone fragment used to assess the age of a Susisuchus anatoceps crocodile specimen.

Picture Credit: PLOS One

The picture above shows (A) the fossil specimen of Susisuchus (MPSC R1136), which is part of the vertebrate fossil collection of the Museu de Paleontologia da Universidade Regional do Cariri (Santana do Cariri, Ceará State, Brazil).  The scale bar for (A) is five centimetres.  The area in red (marked B) and green (marked C) with arrows (corresponding to rib and ulna respectively) indicate where the cuts were made for the bone sample collection. (B) View of the cross section of the ulna. (C) View of the cross section of the rib.  In the scientific journal the scale bar for B and C is reported as being 5 mm but we suspect that this scale is inaccurate for both photographs.

Susisuchus anatoceps

Fossils of this ancient crocodile come from the Crato Formation of Brazil and indicate that Susisuchus lived around 112 to 100 million years ago.  Similar crocodile fossils have been discovered in Australia suggesting that these types of crocodiles may have migrated using river systems that linked these parts of the super-continent Gondwana.  Although, now known to be small, when it comes to Crocodylomorphs Susisuchus punches way above its weight as it is one of the oldest crocodilians with a dermal skeleton very similar to that seen in extent crocodilians (members of the Eusuchia), comprising a dorsal shield comprising of at least six longitudinal rows of osteoderms (dermal armour).  This suggests that Susisuchus is phylogenetically very close to the origin of Eusuchia – modern day crocodiles, caiman, alligators and gharials.

Susisuchus anatoceps  – On the Road to Modern Crocodylians

The fossilised remains of the ancient crocodile Susisuchus anatoceps.

Susisuchus anatoceps fossil material.

Picture Credit: University of Queensland

Despite the wealth of vertebrate fossil material associated with the Crato Formation, crocodile fossils are relatively rare.  Many palaeontologists believe that the Crato Formation deposits, the majority of which represent a brackish, lagoonal type environment was not the natural habitat of Susisuchus, instead the bodies of animals were washed downstream into the lagoon and therefore the carcase may have travelled extensively before final deposition.  It is probable that Susisuchus lived in freshwater environments further inland and it fed on small fish, molluscs and amphibians.

Comparing the Size of Brazilian Cretaceous and Early Palaeocene Crocodiles

Scale comparison of Brazilian Cretaceous Crocodylomorpha.

Comparative size of Susisuchus anatoceps to other Brazilian Cretaceous and Palaeocene Crocodylomorphs.

Picture Credit: PLOS One

The diagram above shows Susisuchus anatoceps (4) compared to three other Brazilian Crocodylomorphs from the Cretaceous and Early Palaeocene namely:

1).  Baurusuchus salgadoensis a 4.5 metre long terrestrial predator named in 2005 kwon from the Adamantina Formation of Brazil which lived around 90-83 million years ago.

2).  Guarinisuchus munizi a 3 metre long marine crocodile known from the Early Palaeocene.

3).  Mariliasuchus amarali a  one metre long, highly terrestrial crocodile known from the  upper part of the Adamantina Formation indicating a Late Cretaceous age (possibly Campanian or perhaps Maastrichtian faunal stage)

Strange Tusked Dicynodont from Brazil

Rastodon procurvidens – A Permian “Tusker” from Brazil

Palaeontologists wanting to learn more about a bizarre group of Permian/Triassic therapsids known as Dicynodonts usually head to the famous Karoo Basin of South Africa, a part of the world famous for its reptile fossils.  So abundant are the various Dicynodont fossils in the strata that make up the Permian and Triassic components of the Karoo Basin Supergroup, that their fossil remains are used to date the rocks in which they are found.  There is no doubting that the Dicynodonts were a very successful group, but what about the rest of Pangaea and their fossil record?

An Illustration of a Typical Dicynodont

A Dicynodont model.

A model of a Dicynodont (therapsid).

Scuttle forward Rastodon procurvidens, only the second Permian Dicynodont to be identified from the Paraná Basin of Brazil.  A team of international scientists writing in the on line, open access journal PLOS One describe Rastodon from a beautifully preserved, albeit slightly crushed fossil skull that was found on a private residence (Boqueirão farm outcrop), located in the municipality of São Gabriel (Catuçaba district), approximately in the central part of the Rio Grande do Sul State, in south-eastern Brazil.

The researchers, which include scientists from the Federal University of Rio Grande do Sul and the Museum für Naturkunde (Berlin, Germany), studied the holotype material, which consists of most of the skull with attached lower jaws and named the animal “Rasto – tooth” in honour of the Rio do Rasto Formation from which the fossils came.  Ironically, as a synapsid reptile, Rastodon is more closely related to mammals such as ourselves than it is to modern reptiles like crocodiles, snakes and lizards.

Left Lateral View of the Skull of Rastodon procurvidens

Rastodon fossil skull from Brazil.

A view of the skull of the therapsid Rastodon.

Picture Credit: Felipe Lima Pinheiro

Odd Tusks

Many types of Dicynodont had enlarged tusks in the upper jaw.  The tusks of Rastodon seem to be extremely unusual, even for this bizarre group of ancient herbivores.  They are very small and curve forwards with the tip of each tusk angled towards the front of the snout.  Phylogenetic analysis indicates that R. procurvidens is the earliest and most basal member of Bidentalia, a cosmopolitan clade that includes Permian and Triassic Dicynodonts whose dentition is usually reduced to a pair of maxillary tusks.   The authors of the scientific paper note that the shape and position of the tusks were not due to post-mortem crushing of the skull bones or due in any part to the fossilisation process.   Both tusks look symmetrical when the skull is viewed from the front end (anterior view) and in addition, each tooth fits neatly into a groove in the lower jaw.  The presence of this embayment or recess confirms that the teeth position and morphology are just about unchanged from when this quadruped scuttled around this part of Brazil the best part of 260 million years ago.  The odd tusks of Rastodon have inspired the trivial name which means “curved forward tooth”.

To read an article about another bizarre Therapsid from BrazilBizarre Sabre-Toothed Permian Herbivore from Brazil

As to the specific function of these strange teeth, well, that remains somewhat of a mystery.

The “Black Sheep” of the Ichthyosaur Family

Making Heads or Tails of Sclerocormus parviceps

No sooner has the likes of Oliver Rieppel, (Rowe Family Curator of Evolutionary Biology at the Field Museum, Chicago) and Nick Fraser (National Museums of Scotland), in collaboration with scientists from China “unzipped” the bizarre Triassic marine reptile Atopodentatus unicus*, another academic paper comes along introducing the equally peculiar looking Sclerocormus parviceps to the world.  A number of media outlets have already covered this news story, but in this article we will take a slightly different approach, focusing on the rapid evolutionary changes that seem to have taken place in marine ecosystems following the End Permian mass extinction event.

The Complete Specimen of Sclerocormus parviceps (Holotype Reference AGB6265)

Sclerocormus parviceps fossil material.

Sclerocormus parviceps fossil material.

Picture Credit: Da-yong Jiang (Peking University)

The photograph above shows the various components that make up the holotype specimen.  The scale bars to the left and in the centre each  measure 25 centimetres in length.  The long, thin, whip-like tail is on the left of the photograph, the skull on the right.

The specimen was excavated from Bed 719 in the Majiashan Quarry, near the city of Chaohu in Anhui Province (eastern China).  These, predominately limestone beds are highly fossiliferous and a huge variety of invertebrate and vertebrate fossils are known from this location.  The strata was laid down in a shallow, tropical sea environment not long after the End Permian extinction event and as a result, the fossils found in these rocks have provided palaeontologists with a unique opportunity to examine how marine fauna bounced back after the extinction that is believed to have wiped out around 95% of all marine life.

Sclerocormus parviceps – Not Your Typical Ichthyosauriform

Writing in the on line journal “Scientific Reports”, the researchers describe this new type of marine reptile as a basal member of the ichthyosauriforms.  The fossil material dates from around 248 million years ago (Olenekian faunal stage of the Lower Triassic), it suggests that if a long-tailed, short-snouted marine reptile existed at this time, then these reptiles must have diversified rapidly during the Early Triassic.  Although, related to the Ichthyosaurs, those dolphin-like, super sleek animals with their long jaws and fishy tails, as S. parviceps was so different from the typical Ichthyosaur body plan it indicates that there must have been a period of very rapid evolution.

A Scale Drawing of Sclerocormus parviceps

A scale drawing of Sclerocormus parviceps.

A scale drawing of Sclerocormus parviceps.

Picture Credit: Everything Dinosaur modified from an illustration by Nicolay Zverkov

Measuring around 1.6 metres long from that stubby snout to the end of the serpentine tail Sclerocormus parviceps is one of the largest types of marine reptile known from the Lower Triassic.  Based on an analysis of the fossil material, in comparison to Late Triassic Ichthyosaurs, Sclerocormus would have been a relatively poor swimmer.  In addition, whilst many of the later Ichthyosaurs evolved into apex predators, the short -snouted Sclerocormus seems to have specialised in eating small, soft-bodied creatures.  The scientists speculate that the toothless Sclerocormus used its short snout to create pressure and suck up food like a syringe.  It looks very different from its relatives and it probably behaved very differently too.  Sclerocormus could be considered the “black-sheep” of this particular group of marine reptiles and as it was so very different from its relatives it tells palaeontologists a lot about the rapid exploitation of ecosystem niches by vertebrates after the mass extinction event.

The Skull of Sclerocormus parviceps (b) and a Line Drawing Illustrating the Individual Bones (b2)

The skull of Sclerocormus parviceps (b) with an explanatory line drawing identifying individual bones (b2).

The skull of Sclerocormus parviceps (b) with an explanatory line drawing identifying individual bones (b2).

Picture Credit: Scientific Reports

The picture above shows (b) a close up of the skull material and (b2) a line drawing indicating the individual position of the bones.  Although, crushed the palaeontologists can make out a lot of detail regarding the skull morphology of this marine reptile.  The scale bars represent 1 cm (b) and 2 cm (b2).

Key

Skull elements. Abbreviations: a?, angular; ar?, articular; d?, dentary; f, frontal; j?, jugal, l?, lacrimal; m, maxilla; n, nasal; p, parietal; pm, premaxilla; po, postorbital; pof, postfrontal; prf, prefrontal; q, quadrate; sa?, surangular; scl, scleral ossicles; sq, squamosal and st, supratemporal.

Commenting on the significance of this discovery, Dr. Rieppel stated:

“Sclerocormus tells us that ichthyosauriforms evolved and diversified rapidly at the end of the Lower Triassic period.  We don’t have many marine reptile fossils from this period, so this specimen is important because it suggests that there’s diversity that hasn’t been uncovered yet.”

The Triassic Timescale and Marine Reptile Diversity

Although, the marine reptile fossil record for the Lower and Middle Triassic is poor, scientists have been able to use recent fossil discoveries from China to help plot the evolution of this important group of marine reptiles.  The authors of the scientific paper plotted the diversity of species during the Triassic and their evidence suggests that there was not a single burst of evolution during the Early to the Middle Triassic, but at least two waves of marine reptile diversification, separated by a decline in speciation.  In addition, the scientists conclude that the first burst of evolution led to a rapid increase in the Ichthyosauromorpha, the ichthyosauriforms such as  Sclerocormus and the related Hupehsuchia.  This was followed by a second period of rapid marine evolution, but this time it was the Sauropterygia (Placodonts and their relatives) and the closely related Saurosphargidae that seem to have evolved most rapidly.

Two Bursts of Marine Reptile Evolution in the Early to Mid Triassic

The diversity of Triassic marine reptiles.

The diversity of Triassic marine reptiles.

Picture Credit: Scientific Reports with additional annotation by Everything Dinosaur

The graph above shows species diversity over time through the Triassic.  The black line in the graph shows raw data from the fossil record, however, as the fossil record for marine reptiles from this time is far from complete, the scientists have inflated the stratigraphic ranges of species to account for gaps in the fossil record.  The red dotted line plots the data where half of the species are assumed to have their records missing from the faunal sub-stages of the Triassic.  The blue dotted line shows a more extreme view where all species known to date are assumed to be missing records from the faunal sub-stages before and after the actual date of a fossil discovery.  The data, however it is plotted, does show two distinct evolutionary phases, lots of new species in a relatively short time.

Explaining the team’s findings in the context of Darwinian evolution, Dr. Rieppel explained:

“Darwin’s model of evolution consists of small, gradual changes over a long period of time, and that’s not quite what we’re seeing here.  These ichthyosauriforms seem to have evolved very quickly, in short bursts of lots of change, in leaps and bounds.”

Gradual change, a sort of slow, creeping evolution may not have taken place in shallow seas immediately following the End Permian extinction event.  With so many vacant niches to exploit, those vertebrates that survived the extinction seem to have radiated rapidly, evolving a myriad of specialist forms such as Sclerocormus parviceps.  This may be an example of “punctuated equilibrium” a form of evolution proposed by the famous palaeontologist Stephen Jay Gould and others whereby evolutionary change occurs relatively rapidly, alternating with longer periods of relative evolutionary stability.

The Triassic Timescale – An Explanation

In the line graph above, Everything Dinosaur team members have labelled the three Epochs that form the Triassic on the horizontal timeline (Lower, Middle and Upper).  Underneath the graph, we have annotated the faunal sub-stages listed by providing a key showing the faunal stage that each sub-stage is associated with (Olenekian, Anisian, Ladinian, Carnian and Norian).  For some readers the term faunal sub-stage may be unfamiliar to them, here is a brief explanation.

Biostratigraphic in conjunction with relative dating and more recently methods such as radiometric dating and palaeomagnetism have enabled scientists to date events preserved in the geological record.  These time intervals allow a geological period, in this case the Triassic to be established.  However, to explore in more detail the geological record laid down over the tens of millions of years represented by a geological period, this immense amount of time is further divided up into epochs, faunal stages and sub-faunal stages.  It is just like the pages of a book being divided up into paragraphs, the pages themselves being grouped into chapters.

The Triassic comprises of three Epochs (also called series): Lower, Middle and Upper

These in turn are divided into seven faunal stages:
Lower = Induan, Olenekian
Middle = Anisian, Ladinian
Upper = Carnian, Norian, Rhaetian

As the faunal stages themselves represent many millions of years, changes in the geological record are used to divide these stages themselves into a series of smaller units called faunal sub-stages:

The seven faunal stages of the Triassic are further divided into fifteen faunal sub-stages namely:

Induan = upper Griesbachian and the Dienerian

Olenekian = Smithian and the Spathian

Anisian= Aegean, Bithynian, Pelsonian and the Illyrian

Ladinian =Fassanian, Longobardian

Carnian = Julian and the Tuvalian

Norian = Lacian, Alaunian, Sevatian

*To read an update on the bizarre Triassic marine reptile Atopodentatus unicus: Atopodentatus unzipped

Life “Loomed Large” 1.56 Billion Years Ago

Multicellular Eukaryotes from  1.56 billion-year-old Rocks (Gaoyuzhuang Formation)

A team of Chinese and American scientists have confirmed the presence of large (several centimetres long in some cases), communities of eukaryotic cells preserved as impressions within rocks laid down in a shallow marine environment some 1.56 billion years ago.  This suggests that organisms had begun to form such structures during the Mesoproterozoic, some five hundred million years or so after the very first eukaryote cells evolved.

Macro-Fossils Preserved in the Mudstones of the Gaoyuzhuang Formation (Northern China)

Examples of various eukaryotic communities preserved in the mudstones of the Gaoyuzhuang Formation.

Examples of various eukaryotic communities preserved in the mudstones of the Gaoyuzhuang Formation.

Picture Credit: Nature Communications/Nanjing Institute of Geology and Palaeontology

Scale bar information for the picture (above) 5 cm (in a,b,g), 20 mm (in c), 40 mm (in d) and 5 mm (in e,f).

The scientists, which included Professor Andrew Knoll (Harvard University), a co-author of the academic paper published in the journal “Nature Communications”, identified a variety of different shaped fossils, some were linear, others wedge-shaped, whilst some were oblong and yet another group were described as tongue-shaped.  In total, fifty-three fossil communities were identified.  Although it is difficult to assign these structures to a place in standard Linnaean classification, a spokesperson from Everything Dinosaur suggested that these ancient life forms could be linked to the Kingdom Protoctista, a biological kingdom which includes certain large, multicellular eukaryotes, such as red algae and kelp.

What is a Eukaryotic Cell?

Eukaryotes have their genetic material enclosed within a nucleus, this is a distinct area within the confines of the cell where the genetic instructions and information can be found.  They also have organelles which are specialised structures within the cell that are responsible for specific areas of activity such as mitochondria for energy production or chloroplasts that convert sunlight energy into sugars (photosynthesis).  The first cells to form lacked a nucleus and specialised structures (organelles), these cells are referred to as prokaryotes (from the Greek which means “before the nucleus”), the DNA of prokaryotic cells is held in the cytoplasm of the cell.

Prokaryote Cells Compared to Eukaryote Cells

Simple diagram showing differences in Eukaryote cells and Prokaryote cells.

Simple diagram showing differences in Eukaryote cells and Prokaryote cells.

Picture Credit: Everything Dinosaur

The diagram above shows the basic differences between prokaryotic and eukaryotic cells.  Note the different scales, due to their unstructured form, prokaryotic cells are much smaller than eukaryotic cells.  Fossil evidence for cyanobacteria (prokaryotes) suggest that these cells first formed some 3.5 billion years ago (Archean Eon)*.  The first eukaryotic cells may have formed around 2.1 billion years ago**.

Eukaryote cells most likely evolved from prokaryote cells at some point in the Paleoproterozoic.  How this came about is a subject of much debate.  One theory proposes predatory prokaryotes engulfed other smaller prokaryote cells.  Instead of these cells being consumed, a symbiotic relationship resulted with the smaller cells becoming the specialised elements of the larger cell.  Another theory suggests that more complex cells came about due to mutations during cellular division.  The presence of DNA strands in mitochondria which are not exactly the same as the DNA found within the host cell nucleus suggests that the mitochondria were once single-celled organisms in their own right.

The Significance of the Gaoyuzhuang Formation

Fossils described as macro-fossils are exceedingly rare in rocks older than the Late Neoproterozoic Era, but uranium – lead (U to Pb) radiometric dating suggests that the biota identified from the mudstones from the Gaoyuzhuang Formation (Yanshan area in the Hebei Province of northern China) are around 1.56 billion years old.  Other geological formations dated to over a billion years old which contain macro-fossils have been identified before, but it is the number and variety of the different types of fossil that marks out this strata as being something special.

Researchers Exploring the Exposed Mudstones Looking for Evidence of Ancient Life

Researchers examine the fine-grained mudstones which form part of the Gaoyuzhuang Formation.

Researchers examine the fine-grained mudstones which form part of the Gaoyuzhuang Formation.

Picture Credit: Nature Communications

Some of the fossilised structures measure up to thirty centimetres in length and eight centimetres wide.  The researchers conclude that the specimens may not represent the oldest know eukaryotes but they are the oldest eukaryotes that exhibit multicellular structures.  These organisms lived in a shallow marine environment and they were probably benthic (lived on the sea floor).  Analysis of the cells indicates that they may have been capable of photosynthesis and although large by Precambrian standards these organisms cannot be described as complex life.

Explaining the difference between complex life and these large multicellular structures, Professor Knoll stated that the Chinese fossils were:

“Large but I doubt that they were complicated – it’s an important distinction.”

Eukaryotic cells are capable of becoming specialised with different cells being responsible for different systems, functions and processes, a vital step on the path to complex life forms.  These cells, preserved as carbonaceous impressions in the rock show no signs of fundamental differentiation at the cellular level.  These fossils provide the best evidence to date that multicellular eukaryotes of large size (greater than a centimetre in length), with a regular shape existed in marine environments at least a billion years prior to the Cambrian explosion.  They are multicellular but they are not the complex, more specialised and differentiated cells associated with more advanced organisms.

Treated Sections of the Fossils Showing the Cell Structure

Treated sections of the Gaoyuzhuang Formation fossils showing cellular structures.

Treated sections of the Gaoyuzhuang Formation fossils showing cellular structures.

Picture Credit: Nature Communications

The picture above shows various views of the cell structure.  Pictures b and d show organic fragments with preserved cellular structure, the scale bar representing 100 μm (microns).  Pictures c and e show polygonal cells forming a multi-layered network (scale bar 20 μm).

The existence of these structures provides further evidence of the diversity of life during the Proterozoic, it also suggests that an increase in oxygen levels in conjunction with the establishment of a protective ozone layer in the Earth’s upper atmosphere may have permitted these multicellular organisms to form.

*/**The dates given for the first fossil evidence of prokaryotes and eukaryotic cells are speculative.

Rare Horseshoe Crab Fossil Discovery from Nova Scotia

The Important Role Enthusiastic Amateurs Play in Palaeontology

Last week Everything Dinosaur reported on the concerns being raised over the extensive amount of digging into cliffs on north Norfolk beaches by fossil collectors.  Whilst we frown upon such activities and urge all fossil collectors to follow the fossil collecting code, today, we report on the significant contribution made to palaeontology by a couple of enthusiastic fossil hunters from Nova Scotia.  Their dedication has resulted in a number of important discoveries, the latest being a new species of ancient horseshoe crab, which is known from just two specimens.

To read the article about concerns over coastal Norfolk fossil sites: Experts Fear for Safety of Fossils and Fossil Collectors

Say Hello to Paleolimulus woodae – A 360 million-year-old Horseshoe Crab

Paleolimulus woodae fossil from Blue Beach (Bay of Fundy)

Paleolimulus woodae fossil from Blue Beach (Bay of Fundy)

Picture Credit: CTV News Atlantic

Lower Carboniferous Sandstones and Silts of the Bay of Fundy

The Blue Beach area of the Bay of Fundy (Nova Scotia), is one of the most important Late Palaeozoic fossil locations in the world.  The strata is being constantly eroded by the exceptionally powerful tides (a macro tidal environment) and the eroding cliffs are giving up the fossilised remains of animals and plants that lived in the very Early Carboniferous period (Lower Mississippian Epoch – Tournaisian faunal stage).  The body and trace fossils found here record life in a estuarine environment bordered by dense swamps that existed some 360 million years ago.  Thanks to the efforts of husband and wife team Chris Mansky and Sonja Wood, tens of thousands of fossil specimens have been retrieved from the beach.  The rocks have such significance as they preserve fossils of some of the very first Tetrapods – primitive amphibians that were the first terrestrial vertebrates.  Working in conjunction with scientists from the New Mexico Museum of Natural History and Science, an extremely rare horseshoe crab has been identified and described as a new species.  The species name honours Sonja, the ancient Arthropod has been called Paleolimulus woodae (pronounced pay-leo-limb-mew-lus wood-i).

A Natural Goldmine for Fossils

Commenting on the significance of the fossil find, co-author of the scientific paper that has just been published in the academic journal “Neues Jahrbuch für Geologie und Paläontologie”, Chris Mansky stated:

“We’re sitting on an unrealised bonanza or mother-load of information.  It’s a very small scarp that shows probably one of the most important pieces of evolutionary information.”

The powerful tides scour the beach and cliffs twice a day exposing fossil material all year round.  The work of Chris and Sonja is vital, as without their help, many important fossil specimens, such as the ten pence sized horseshoe crab fossil would be lost.  The couple have run the Blue Beach Fossil Museum since 2002, and they have amassed a collection of some 90,000 lbs of rocks containing body fossils of early Tetrapods, ancient fish, molluscs, as well as important trace fossils, preserving tracks in the mud made by both back-boned animals and invertebrates.

Sonja Wood of the Blue Beach Fossil Museum Holding One of the Specimens of  Paleolimulus woodae

Sonja Wood Holding a specimen of her namesake - P. woodae

Sonja Wood Holding a specimen of her namesake – P. woodae

Picture Credit: Colin Chisholm – Hants Journal

Romer’s Gap* and All That

Horseshoe crabs are marine Arthropods, (Order Xiphosurida, Family Limulidae), known as living fossils as they seem little changed since their evolutionary origins some 450 million years ago.  A number of genera exist today, but populations are threatened due to habitat destruction and the removal of eggs for human consumption.

An Illustration of a Extant Horseshoe Crab

An illustration of a Horseshoe Crab (a living fossil).

An illustration of a Horseshoe Crab (a living fossil).

Picture Credit: Everything Dinosaur

The Blue Beach location is regarded as one of the most important Lagerstätte (strata with an abundance of fossils), of the Late Palaeozoic.  The Lower Carboniferous rocks are helping to provide scientists with information about vertebrates to fill in “Romer’s Gap”, a discontinuity in the fossil record between the end of the Devonian and the first fifteen million years of the Carboniferous, a time when terrestrial ecosystems were rapidly evolving and the first land animals with back-bones were becoming widespread.  The gap in the geological record is named after the American palaeontologist Alfred Sherwood Romer who first recognised this discontinuity.

Explaining just how rare the horseshoe crab fossils are, Chris Mansky said:

“Out of the tens of thousands of fossils that have been gathered [from the Blue Beach area] only two were horseshoe crab.”

The fossil material including body impressions and tracks made by the horseshoe crabs in the soft mud are helping scientists to piece together more information about this ancient palaeoenvironment.  Today, we pay tribute to Chris and Sonja whose efforts are helping scientists to learn more about a crucial period in the evolution of life on Earth.

Romer’s Gap* An Explanation

The gap in the fossil record that marks the beginning of the Carboniferous geological period.  In sedimentary rocks fractionally older than Romer’s Gap palaeontologists have unearthed evidence of very primitive Devonian Tetrapods , fish with fingers, lots of fingers.  Tetrapod fossils found in slightly younger rocks provide evidence of Carboniferous Tetrapods that all had five fingers and toes and they are much better adapted to terrestrial habitats.

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