Sponge-like Fossils may be Evidence of Earliest Animals Known to Science

A team of researchers writing in the scientific journal “Nature Geoscience” claim that an analysis of limestone strata (stromatolites formed by bacteria) from the Flinders range in South Australia, may have produced evidence of the first complex animals known, a form of ancient sponge.  Analysis of these strange “body” fossils undertaken by Geoscientists based at Princeton University (New Jersey, United States), suggests the presence of primitive sponge-like organisms dating from approximately 650-640 million years ago.  These fossils pre-date the presence of other complex animal fossils in the fossil record by about seventy million years.

Photographs show two stromatolite formations.  Stromatolites are layered, mound-like structures, sometimes reaching more than a metre tall.   These structures are built up over many years in shallow and warm tropical waters by sheets of bacteria growing over the seabed and trapping sediment.  Evidence for stromatolites have been found in rocks dating from 3 billion years of age.

The research team, led by Professor Adam Maloof and assisted by Geoscientist Catherine Rose suggest that the strange, bizarre calcite based forms preserved in the limestone are the fossilised remains of sponges.  The shapes, which vary from ovals, anvils, wishbones and rings some of which measure more than one centimetre long represent body fossils according to the Princeton University researchers.

Broadly there are two main types of fossils.  Firstly, there are body fossils, these preserve something of the bodily remains of animals or plants.  For example, the cast exoskeleton of a lobster or trilobite, fossil bones, teeth, plant remains and such like.  Secondly, there are trace fossils, these preserve evidence of the activity of animals such as tracks, insects bore holes in wood, burrows in sediment and footprints.  Technically, there are other sorts of fossils such as what is referred to as “chemical fossils” evidence preserved in rocks of the chemicals that we know can only be produced by life processes.  There are also micro-fossils, tiny, microscopic body and trace fossils such as pollen grains and other fossil material that is only able to be viewed using microscopes or other technology.

Ancient Sponge

The American based researchers suspected that the peculiar shapes entombed in the limestone might be parts of the bodies of ancient organisms, the use of sophisticated 3-D imaging techniques affirm their theory.

A Model of an Ancient Sponge-like Animal (Vauxia)

A model of an ancient sponge.

The model of the ancient sponge-like animal is from a set of Cambrian replicas in the Wild Safari Toobs range.

To view this range: Wild Safari Prehistoric World Models and Toobs.

The theory is controversial, as if the scientists are correct, then they have discovered fossils of creatures that existed in the Cryogenian period.  This geological period is estimated to have lasted from about 850 million years ago to approximately 635 million years ago, although the exact duration of this particular part of the geological time-scale is disputed, it is thought that the Earth went through dramatic climate changes resulting in a global Ice Age, when the entire planet become covered in ice, leading to the concept of a “snowball Earth”.  To have discovered the remains of relatively sophisticated creatures that have survived beyond the Cryogenian into the Ediacaran period would be a remarkable discovery and enhance the reputation of the Flinders Formation as a major location for Proterozoic fossil finds.

Professor Maloof commented:

“No one was expecting that we would find animals that lived before the ice age [global freezing event – “snowball Earth”] and since animals probably did not evolve twice, we are suddenly confronted with the question of how a relative of these reef-dwelling animals survived the “snowball Earth”.”

A spokesperson from the National Science Foundation, which funded the study, stated that the find is at least seventy million years older than any other evidence of animal body forms in the known fossil record.

Professor Maloof added:

“People have certainly proposed complex organisms, like eukaryotic algae [organisms with cells that contain a nucleus] or protists, and have even proposed animals in the form of trace fossils (preserved tracks) prior to the sponges that we report.  But I think we could confidently say that our sponges are the first somewhat convincing body fossils of an animal before the Ediacaran period.”

The Ediacaran Hills

The Ediacaran hills, part of the Flinders Range in South Australia have already provided fossil evidence of some amazing soft bodied organisms.  In 1946, geologist Reginald Sprigg was searching for signs of mineral deposits when he discovered the remains of several bizarre Precambrian animals.  Creatures such as Tribrachidium, Yelovichnus and Spriggina (which is named in honour of him).  These animals comprise a range of organisms classified as Ediacaran fauna and are so unusual and strange that most cannot be associated with known Phylum.  For example, Spriggina could be a primitive, basal trilobite or possibly a segmented worm.

Due to the fact that the animal fossils were made of the same mineral material as the limestone rock (calcite), the scientists were unable to remove them from the matrix.  Instead, the researchers collaborated with Situ Studio, a specialist imaging company to produce digital models of the strange structures.

By carefully slicing off thin layers of rock, each about 50 microns in diameter and photographing it after each layer was removed, the team managed to create a 3-D model of the animals.  The model revealed a series of irregularly shaped bodies up to one centimetre in size (marble sized) with an internal network of interconnected millimetre-wide channels.  The presence of the channels and their structure are the interesting elements to the palaeontologists.  Such structures are found in sponges, it is these channels that have water drawn into them that permit these organisms to feed.  Could these microscopic channels be evidence of Precambrian sponge-like lifeforms?

The researchers suggest that at least three of the specimens had a short, tube-shaped pedicle at the base.  This may have been used to attach the creature to a solid surface.

Proterozoic Lifeforms

The oldest fossil sponges previously found lived around 520 million years ago.  However, chemical traces from materials of cell membranes (steranes) of sponges were discovered in 2009 in sedimentary rocks more than 635 million years old.

However, the theory put forward by the Princeton team is disputed.  In a dismissive statement; Dr Jim Gehling, a Senior Research Scientist from the South Australian Museum said that he saw no convincing evidence to support the interpretation that the “coco-pop breakfast-cereal-like forms” were ancient sponges.

He went on to add:

“They may just as easily be mineralised bacterial cells or some other sort of single-celled microbes.  Sponges should have first appeared in the Cryogenian Period about 650 million years ago – judging by times of branching in family trees in the Animal Kingdom, based on molecular clocks and the discovery of sponge biomarkers (steranes) preserved in rocks of this age.”

However, it is difficult to interpret the fossil evidence as scientists have no real data on what the earliest types of sponge-like organisms actually looked like.

Dr Gehling stated:

“The problem is that we have no idea what the very earliest sponges may have looked like.  This means that the discovery of any weird shape in rocks of this age may lead to claims of the ‘oldest sponge-grade fossils’.”

Our knowledge of Proterozoic lifeforms has increased dramatically over the last thirty years or so.  New insights into existing fossil specimens have occurred thanks in the main to the use of sophisticated new examination techniques.

Dramatic Climate Change Led to Demise of the Woolly Mammoth

New research published in the scientific journal “The Quaternary Science Review” by a team of British based scientists suggests that dramatic global climate change led to the demise of mega fauna such as the Woolly Mammoth and not predation by humans.

Researchers from the University of Durham in collaboration with scientists at the London Natural History Museum have concluded that by 11,400 years ago, most of the large mammals that had roamed across the Northern Hemisphere, animals such as the Giant Elk (Megaloceras), the Woolly Rhino and the Woolly Mammoth had become extinct.  Although hunting from the rapidly expanding human population may have had an effect, the loss of extensive areas of grassland and the re-forestation of northern Europe and Asia was the real reason for these animals extinction.

Woolly Mammoth

Our ancestors would have competed with these large mammals for space and food but it was sudden and dramatic climate change that led to the demise of most of the mega fauna at this time the scientists conclude.

Their findings are part of the most comprehensive study carried out so far on climate change and its impact on the flora and fauna of the northern hemisphere after the height of the last Ice Age, 21,000 years ago.

A rapid and sustained period of post-glacial global warming led to a rapid decline in open grasslands as much of northern Europe and Asia became woodland and forest.  Although Mammoths were descended from forest dwelling elephants, the rapid change in habitat was just too quick to enable these large, shaggy elephants to adapt.  The climate changes that led to the change in the landscape and its flora made survival impossible for the big grazing herbivores and the predators that fed on them.

Although Woolly Mammoths are often depicted in icy, glacial environments these elephants were animals of the open plain and fed on grasses, sedges and other ground dwelling plants.  The loss of their habitat led to their demise, claim the research team.

An Illustration of a Family of Woolly Mammoths

Picture credit: Schleich

To view a model of Woolly Mammoth and dinosaur toys: Papo Prehistoric Animal Models and Dinosaurs.

Over the last two or three years, there have been a number of papers published, assessing the impact of global climate change on mammal populations.  Perhaps this is a reflection of the concerns expressed over the problem of dramatic climate change that threatens our own species.  Last year, we reported on some research work that set out to accurately date some Mammoth fossils that had been found in Shropshire, England, using radiocarbon dating.

To read more about radiocarbon dating work on Mammoth fossils: Radiocarbon dating changes date of Mammoth Extinction.

The Last Refuge of Woolly Mammoths

One of the principal authors of the study, Professor Brian Huntley of the School of Biological and Biomedical Sciences (Durham University) stated:

“Woolly Mammoths retreated to northern Siberia, 14,000 years ago, whereas they had roamed and munched their way across many parts of Europe, including the UK , for the previous 100,000 years.”

Commenting on the suggestion that our ancestors may have been at least partially responsible for the Mammoth’s extinction, Professor Huntley said:

“It would have been difficult for man to wipe them out [Woolly Mammoths] because our species was not so widespread then and did not have the technology.  We know from Mammoth fossils that they were hunted by humans, but they would not have been an easy kill because of their size.”

The British based research team point the finger at rising temperatures, the factor that led to the extinction of animals as diverse as Woolly Rhinos, the Mammoths, giant deer and the large meat-eaters that preyed on them.

Although some small, isolated pockets of animals may have clung on for a little longer, the climate change and loss of habitat that resulted had effectively sealed the fate of these species the scientists conclude.

A Replica of an Adult Woolly Mammoth and Calf

The CollectA Deluxe Woolly Mammoth model in 1:20 scale and the CollectA Prehistoric Life Woolly Mammoth calf.

Picture credit: Everything Dinosaur

Summarising the study, Professor Huntley stated:

“Mega-mammals found it increasingly difficult to find food.  We believe the loss of food supplies from productive grasslands was the major contributing factor to extinction.”

Evidence of Stone Tool use by Australopithecus afarensis

The fossilised remains of two ancient animal bones dating from 3.4 million years ago discovered in Ethiopia have put back the use of stone tools by early hominids by some 800,000 years according to a new scientific study.

Researcher Zeresenay Alemseged of the California Academy of Sciences believes that the bones show evidence of being cut and smashed by stone tools, this could be the first evidence of stone tools used by a species of Australopithecus (A. afarensis).

Australopithecines

The Australopithecines represent an extinct group of small but upright-walking, ape-like human ancestors that lived from approximately 4.5 million years to about 1.4 million years ago.  Australopithecus afarensis is estimated by scientists to be the most likely ancestor of the human lineage.  This particular species was named as fossil remains were first found in the Afar region of northern Ethiopia.

Perhaps the most famous of all the early hominid fossils known is that of “Lucy” a female Australopithecus afarensis, nicknamed “Lucy” after the discoverers were listening to the Beatles track “Lucy in the Sky with Diamonds” when the fossils were first located.  Known in the scientific community by the slightly less inspiring name of A. L. 288 this early hominid dates from approximately 3.2 million years ago and about 40% of the skeleton was recovered.  “Lucy” stood a little over one metre tall and importantly, the limb bones show that she walked upright.

Early hominid fossils are extremely rare and it is likely that this particular species was quite widespread across central and east Africa.  The large distance between the fossil sites has led scientists to postulate that this particular species of ape-man was quite widespread.

Examples of Stone Tools on Display in a Museum

A collection of typical Stone Age Tools. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Commenting on the conclusions drawn from the study Zeresenay Alemseged stated:

“We are putting stone tools in their hands!”

However, other palaeoanthropologists have urged caution.

The authors of the report state that the bones indicate that human ancestors used sharp stones to carve meat from the carcasses of large animals and other stones to smash bones to get to the marrow.  Being able to feed on marrow would have been very important to our ancient ancestors.  This foodstuff would not be readily accessible to other predators and even if a carcase had been picked clean by vultures and other scavengers, early hominids could still get a highly nutritious meal by breaking the bones and feeding on the protein rich marrow inside.

Some scientists have suggested that the ability to feed on protein rich marrow may have been crucial in the development of larger brains.

One of the bones analysed belonged to a herbivore about the size of a modern cow, the other bone in the study is a leg bone from an animal about goat sized.  No stone tools were found at the site.

The research team have also concluded that these fossils represent the earliest evidence for meat-eating amongst hominids.  The study authors attribute the stone tool use to A. afarensis as no other hominid species is known from that region and rock strata.  “Lucy”, herself was discovered in the same general area, so if this is “smoking gun” evidence of stone tool use then Australopithecus afarensis is the most likely to be the tool user.

Stone Age Tools

Alemseged commented that our ancient relatives probably scavenged carcasses rather than hunting live animals.  They also ate the meat raw has fire had not been mastered yet.  The research team are unable to state whether the stone tools were made or whether they were simply stones that were used as tools.  The intention is to continue the fieldwork in order to establish more evidence.

Alemseged made the point that as some A. afarensis stripped meat from a carcase, others probably stood guard to ward off other scavengers and predators in return for some of the meat, which would indicate a degree of cooperative behaviour.

Until this new study, which has been published in the scientific journal “Nature”, the earliest sign of tool use dates to approximately 2.6 million years ago, also from Ethiopia, but scientists are not sure what species used these tools.

Other experts remain sceptical regarding this particular study’s conclusions.

Nicholas Toth of Indiana University, a palaeoanthropologist who has specialised in the study of early stone tools stated:

“I’m very cautious about the conclusions.”

He went on to point out that the bones in this new study were actually found on the surface rather than being excavated from a layer of sedimentary rock.  This means that nobody can be sure exactly what strata the bones come from, which is crucial to knowing their true age.

The marks on the bones may not be from the impact and use of stone tools.  Toth noted that the pictures he had seen were inconclusive, the notches and marks could have been made by trampling or animal bites.

Tim White of the University of California (Berkeley) commented that the tooth marks in his opinion looked like the work of crocodiles, he also pointed out that the marks do not appear in the places on the bones that one would expect from a butchering.

Noting that in 30 years of searching for fossils, no stone tools as old as the bones have been found – White stated:

“The evidence is very thin here, and very ambiguous.  An extraordinary claim requires extraordinary evidence.”

Other experts are more supportive of the study’s conclusions, Bernard Wood of George Washington University declared:

“I’d be willing to bet a month’s salary that those cut marks are from stone tools and not tooth marks.”

Commenting further Bernard went on to state that the bone markings:

“Are as significant a statement about early hominid behaviour as the Laetoli footprints are about hominid locomotion.  Whilst it is reasonable to assume that A. afarensis wielded the tools, the idea about the butchers being guarded by other group members in exchange for meat is pushing the envelope a bit far.”

Wood also said the finding suggests A. afarensis ate meat but doesn’t prove it, because maybe they cut off animal flesh just to get to the marrow.

For models of early hominids including the popular “Evolution of Man” model set (whilst stocks last): Wild Safari Prehistoric World.