Egg-Laying Dinosaurs Doomed Whilst Mammals Live-Birth Reproduction Strategy Triumphed

A team of scientists based in Switzerland have used computer models comparing how dinosaurs grew from a hatchling into an adult with the growth rate of mammals to suggest that the dependence on egg-laying was a factor in the demise of the Dinosauria.  They have added a new twist to the dinosaur extinction theory.

Dinosaur Extinction Theory

Given the physical limitations imposed on the size of hatchlings, dictated by the physical limits of the eggs they hatch from, many dinosaur species had to grow from babies just a few tens of centimetres long into thirty metre and forty tonne giants.  Small, baby dinosaurs having to grow quickly could not compete against mammals that gave birth to much better developed mammalian offspring who could benefit from being suckled by their mothers.

The dinosaurs became extinct approximately sixty-six million years ago, the exact reasons for the extinction of the Dinosauria along with about seventy percent of all terrestrial life at the end of the Cretaceous are still debated, however, within a few million years, life on Earth had recovered and the mammals were rapidly diversifying to fill many of the niches in the ecosystem that were once occupied by dinosaurs.  A team of researchers from the University of Zurich (Switzerland), have used a complex, mathematical model to plot how mammals with their different strategy over reproduction may have gained the ascendancy over those type of dinosaur that survived until the very end of the Mesozoic.

Did the Dinosauria’s Reliance on Eggs Lead to their Demise?

Did a reliance on egg-laying Lead to the extinction of the dinosaurs?

Picture credit: Everything Dinosaur

To view models and figures of extinct non-avian dinosaurs and other prehistoric animals: Safari Ltd Dinosaur Models.

In press releases concerning this new research, detailed in the scientific journal “Biology Letters”, it has been suggested that the mammals won a sort of evolutionary victory over the egg-laying dinosaurs but this does very probably, over simplify the complex environmental factors that were influencing evolution at this crucial time in our own species’s history.  Had the dinosaurs not died out, it is unlikely that there would be the diversity of mammal types around today and it could be argued that the primates, including our own species – Homo sapiens may not have evolved at all.

Ontogenic Studies

The Zurich based scientists looked at how the two sorts of animals (mammals and dinosaurs) grew, they studied the ontogenic properties of typical dinosaurs and mammals that were alive around sixty-six million years ago.  As dinosaurs hatched, they would have had to compete for food with other dinosaurs as well as mammals, whilst the offspring of mammals had their mother’s milk to sustain them.  In addition, dinosaurs had to grow very quickly, for example a baby titanosaur (long-necked dinosaur), may have had to put on more than one kilogramme of body weight a day – a rate of weight gain not seen in the much smaller mammal genera around at the time.

As baby dinosaurs grew, the young animals would have had to compete in several size categories for food, including adults of other animal groups.  This, the scientists claim put the Dinosauria at a distinct advantage and this may help explain why they died out but the majority of mammals did not.

Those niches in the food chain for small and medium-sized animals were already “occupied”, with the intense competition for depleted food reserves after an extraterrestrial impact, volcanism and climate change leaving no room for the dinosaurs.

Being relatively small, as in the case of the Mammalia at the end of the Cretaceous may have been key to their survival, the fossil record suggests that immediately after the extinction event there were very few terrestrial animals larger than a Labrador dog (around 25 kilogrammes).  Some mammals also lived in burrows and bred very rapidly, these factors too could have assisted in the Order’s ultimate survival.

A Fossilised Dinosaur Nest showing Eggs

Two dinosaur eggs. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The Swiss team claim that smaller mammals were able to cope with the post-extinction environment much more effectively than their egg-laying competitors and this led them to evolve and diversify very rapidly in the Cenozoic, rapidly occupying all the niches once held by the dinosaurs.

The team aimed to answer the question using their mathematical model as to why the Dinosauria died out yet the Mammalia survived?  Could adult body mass, and an egg-laying reproduction strategy hold the answer?

Contrary to popular belief, compared to their eventual adult size, many dinosaurs hatched from comparatively small eggs.  The largest dinosaur eggs known in the fossil record are believed to have been laid by titanosaurs (long-necked dinosaurs), these eggs are roughly football-sized and from a hatchling, perhaps less than one metre long and weighing a few kilogrammes, these animals would grow to become a forty metre long, forty thousand kilogramme adult animal.

The discovery of some bizarre, egg-shaped structures by construction workers in Chechyna has recently been featured in a number of media outlets.  The egg-shaped objects, some more than a metre in circumference were believed by some observers and academics to be the fossilised remains of a dinosaur nesting site.  However, palaeontologists have cast doubt over the authenticity of these claims as the structures are simply “too big” to be dinosaur eggs.

To read more about this story: World’s Largest Dinosaur Eggs – The Facts are Scrambled.

The size of an animal that can hatch from an egg is governed by a number of factors.  Firstly, the egg shell has to be thin enough to allow gaseous exchange between the external environment and the embryo inside the egg.  The egg shell has to be thin enough to allow a baby to hatch, to break out of the egg.  If dinosaur eggs were much bigger, then the egg shell surrounding them would have to be much thicker to support the weight of the liquid and the embryo inside.  The egg shell would have to be many times thicker to accommodate this extra weight and therefore, too thick for a baby to break out of.  If the egg shell remained thin as egg size increased then a great many eggs would never hatch as the eggs would crack and split long before the embryo had developed enough to be able to hatch.  Egg size is also limited by the ability of the female to store eggs, to divert enough calcium to permit the formation of egg shell in her body and to allow the passing of eggs via the oviduct so they can be physically laid.

The scientists compared the growth rate of the largest land mammal today, the African elephant (Loxodonta africana) to that of a typical Late Cretaceous titanosaur, the largest type of dinosaur around at the very end of the age of reptiles.  The Swiss team suggested that a titanosaur hatchling was 2,500 times lighter than an adult titanosaur, whilst the African elephant calf was only twenty-two times lighter than its mother.

Cretaceous Mass Extinction Event

Many papers have been written on the Cretaceous mass extinction event.  Egg-laying animals may have been more vulnerable to climate change and this could have been a factor in the demise of the Dinosauria.  However, monotreme mammals (mammals that lay eggs and give birth to very underdeveloped young), did survive the extinction event.  Birds too, survived and they all lay eggs (classified technically as avian dinosaurs).   Body size and the amount of resources needed to sustain a viable breeding population may be a more significant factor in the lottery of life that occurs during an extinction event.  The scientific paper does not help to explain how the pterosaurs or the marine reptiles died out.  Some marine reptiles were viviparous, able to give birth to live young, yet these animals too, went the way of the dinosaurs.

The dinosaurs reliance on an egg-laying reproduction strategy may well have played a role in their eventual demise, but during the Late Cretaceous extinction event all sorts of terrestrial animals became extinct – reptiles, mammals, amphibians and birds.   Thanks to a few types of mammals surviving into the Cenozoic we have the great diversity of mammals seen today.  Within ten million years or so, the main groups of modern mammals had evolved including those prosimians that were to lead eventually to our own species.

Visit Everything Dinosaur’s award-winning website: Visit Everything Dinosaur.

Anglo/Japanese Scientific Team Conclude that Carrying More Food Improved Survival

For our ape-like ancestors being able to use your  hands to grab extra food and run away may have had an important evolutionary influence in early hominids adoption of an upright stance and bipedal walking habit.  That is one of the conclusions made by a joint British/Japanese research team who have been studying the behaviour of extant apes.

Early Hominids

The anthropologists carried out their research studying the complex social behaviours of perhaps our closest living relative – the chimpanzee.  The research team found that these apes, very adept at and more comfortable walking on all fours than walking upright, would adopt a bipedal stance when they needed to monopolise scarce food resources by grabbing more in a single attempt when facing stiff competition from other social group members.

The researchers from Cambridge University (England) and Kyoto University in Japan, concluded that the benefits of being selfish and grabbing as much as you could with both hands would lead to certain individuals getting more than others.  Over a long period of time, natural selection could have favoured those apes that had a better sense of balance and could adopt a bipedal pose to swipe as much food as they could.  This suggest that early hominids could have evolved bipedalism in response to gaining an advantage when competing for scarce food resources – leading to our ancestors becoming permanent bipeds with their hands freed from the role of locomotion for evermore.

There have been many theories postulated as to why a bipedal stance was adopted by our ancestors, those apes that would lead to the emergence of the hominids and eventually our own species H. sapiens.  Studies of Bonobo chimps (Pan paniscus), long-legged, slightly smaller members of the Pan genus of chimpanzee, found in central Africa, led to some scientists concluding that our ancestors became adept at walking upright when they inhabited ancient swamps and regularly had to wade through water.  Most palaeontologists believe that Africa became much drier and the forests gradually became grasslands during the time of the first hominids.  This dry climate and the loss of an arboreal habitat may have driven certain types of apes onto the savannahs and being able to stand tall to look out for danger could well have been a stimulus for a bipedal evolution.

Recent Scientific Papers

There have been a number of recent papers on ancient African hominids, one of the most exciting discoveries was made in southern Africa, the finding of one of the earliest known specimens of the “human family tree”.

To read more about this discovery: New Fossils May Help Redefine Human Ancestry.

Anthropologists studying chimpanzees found that the great apes, who usually walk on all fours, walk upright and free their hands for carrying when they need to monopolise hard-to-find resources by swiping more at a single attempt in the face of fierce competition.

The team from the University of Cambridge and Kyoto University in Japan believe the benefit of “first come, first served” and getting a bigger share of scarce food supplies could, over a long period of time, have led some of our earliest “hominin” ancestors to evolve into “bipedal” primates walking on two legs permanently instead of four.

Professor William McGrew, from Cambridge’s department of archaeology and anthropology, said:

“Bipedality as the key human adaptation may be an evolutionary product of this strategy persisting over time. Ultimately, it set our ancestors on a separate evolutionary path.”

Scientists believe that man’s ancestors changed how they moved at a time of climate upheaval which reduced the forested areas in which they lived and forced them out into the open more. But a lack of fossils means there is division over what specific factor it was that led to the development of walking on two feet.

The research by the team led by PhD student Susana Carvalho and Professor Tetsuro Matsuzawa, published in the journal Current Biology, suggests our earliest hominid ancestors may have lived in shifting environmental conditions in which certain resources were not always easy to come by.

Chimpanzees are one of several ape species able to walk on two legs for short periods of time.

The scientists conducted two studies of chimpanzees in Bossou Forest in Guinea, west Africa, finding that when supplies of highly prized coula nuts were scarce, the chimps were more likely to walk on two feet in an attempt to carry off more in a single trip.

They also found that when the chimpanzees went “crop raiding”, 35% of their activity involved some sort of bipedal movement, and “once again, this behaviour appeared to be linked to a clear attempt to carry as much as possible in one go”.

By studying the behaviour of chimpanzees, they believe that over time, intense bursts of bipedal activity in early hominins may have led to anatomical changes that in turn became the subject of natural selection where competition for food or other resources was strong.

Commenting on the research, Professor William McGrew (Cambridge University’s department of Archaeology and Anthropology) stated:

“Bipedality as the key human adaptation may be an evolutionary product of this strategy persisting over time. Ultimately, it set our ancestors on a separate evolutionary path.”

Walking on your hind legs in a grassland environment makes sense for a number of reasons.  For example, with the brain held slightly higher off the ground when compared to a four-footed form of locomotion it is effectively cooled by being that much further away from the ground.  Hands can be freed up to allow the carrying of food and even simple tools.  A lack of hominid fossils means that there is a lot of debate over what specific factor(s) led to the development of a human-like habit of walking on your back legs.

The work of PhD student Susana Carvalho and Professor Tetsuro Matsuzawa, has been published in the scientific  journal “Current Biology”.  Their work suggests our earliest hominid ancestors may have lived in shifting environmental conditions in which certain resources were not always easy to come by.  Using the observed behaviour of extant apes, such as chimpanzees in the wild, the team postulate that the ability to grab as much as you can could have been a stimulus for bipedalism in our ancestors.  Chimps are just one of several great apes that can walk on their hind legs for a short period, although the position of their hind legs  relative to their pelvic girdle prevents them from walking very efficiently – they tend to swagger using their arms to help balance themselves, whilst human locomotion is a much more bio-mechanically efficient affair.

As the scientists concluded:

“Once again, this behaviour appeared to be linked to a clear attempt to carry as much as possible in one go”.

The study of an extant ape, has led this joint Anglo/Japanese team to conclude that intense bursts of bipedalism in our ancient ancestors may have led to the evolution of anatomical adaptations that led to a more efficient and effective upright stance.  Becoming a biped so that you can use your hands to grab as much food as possible may have been the evolutionary spark that lit the touch-paper that over millions of years led to the emergence of our own branch of the hominid family tree.

To read another article on the evolution of bipedalism in early hominids, an article written about some of the fossil evidence in support of an upright walking stance in A. afarensis: Early Hominid Walking Tall.

The scientific paper: “Chimpanzee carrying behaviour and the origins of human bipedality” by Susana Carvalho et al published in Current Biology.

For models and replicas or early hominids and other creatures: Prehistoric Animal Figures and Models.

Who were the Red Deer People?

A paper published in the online scientific journal PLoS One (public library of science) details the discovery and analysis of ancient human remains which may provide evidence that south-western China was once populated by an ancient species of hominids, a species that is entirely new to science.

The Red Deer People

An international team of researchers including scientists from the University of New South Wales (Australia) have been analysing the fragmentary fossil remains of ancient humans, their studies show that these humans have a mix of both modern and ancient traits.  They could be the last vestiges of a hominid that survived to the Pleistocene/Holocene transition or perhaps evidence that our own species interbreed with more ancient hominids on arrival in Asia.  Dating work including analysis of charcoal deposits left by the cave people as they cooked their food suggest that the fossils are between 14,300 and 11,500 years old – very recent in terms of the geological record.

Team co-leader Darren Curnoe, of the University of New South Wales, commented that the physical appearance of these extinct people was unique, like nothing seen in the Asian hominid record to date.

He stated:

”They look very different to all modern humans, whether alive today or in Africa 150,000 years ago.”

Skeletal Evidence

Skeletal evidence and the results of DNA analysis indicate that our species evolved in Africa before migrating and populating every continent.  It is thought that modern humans migrated into Asia across the Arabian peninsula something like 60,000 years ago.  Evidence from early H. sapiens and H. neanderthalensis  sites is open to a number of interpretations as the archaeological record suggests a complex migration pattern with groups of modern humans and Neanderthals moving in and out of the region in response to changing climate.  The Tibetan plateau may have acted as a natural barrier permitting an ancient hominid species that may have migrated through the Indian sub-continent and eventually present in south-west China to remain excluded from the incursions of more modern species.

Pleistocene aged human fossils are rare in East Asia.  Finds are very scarce but a number of discoveries in south-western China are helping to document the history of human migration into that part of the continent.  This international team, studied a partial skull which was carefully extracted from a block of sediment collected in 1979 from the Longlin Cave (Guangxi Province).  Although the fossil had been found nearly 35 years ago, it had not been properly studied.  This specimen was compared to other human remains found at a cave known as the “Red Deer Cave” due to the number of fossil deer bones found (Maludong, Yunnan Province), mostly fragmentary specimens but as yet undescribed human bones.  The bones found at these different locations suggest that they represent a single population, one type of people with a mixture of ancient and modern anatomical characteristics.

The Partial Human Skull (Longlin Cave)

The flattened facial features can be clearly made out.

Picture credit: PLoS One/Curnoe et al.

The prehistoric people had short, flat faces with ancient features reminiscent of H. heidelbergensis such as thick skull bones  and big teeth but brains with modern-looking frontal lobes.  Known as the “Red Deer People” due to their apparent reliance on an extinct species of deer for food, these humans are the youngest people in terms of geological age, found to date that do not resemble our own human species.

Two Possible Explanations

The research team have put forward two possible explanations for the existence of this unknown human species in this region.  Firstly, they could be modern humans (H. sapiens) that migrated out of Africa very early and reached China independently of other human migrations out of Africa.  Once in China these people did not contribute genetically to people living in East Asia today.

Secondly, the fossil material could represent an unknown species of hominid, deer hunting, venison eating people who lived at a time when our own species was adopting a more sedentary existence rather than the hunter/gatherer way of life, with the development of agriculture.

Although cautious, Professor Curnoe favours the new human species theory, he stated:

”While finely balanced, I think the evidence is slightly weighted towards the Red Deer Cave people representing a new evolutionary line.”

The find follows the discoveries of two new human species in Asia, dubbed “the Hobbit”, (H. floresiensis) due to their small size and the Denisovans, in the last decade or so.  The Indonesian island of Flores was home to a diminutive species of hominid up until approximately 13,000 years ago.

To read more about the Denisovans: X-woman Competing with Modern Humans and Neanderthals.

The discovery team, co-led by Professor Curnoe and Professor Ji Xueping, of Yunnan University in Kunming, includes researchers from five Australian and six Chinese institutions.  This work is invaluable in helping archaeologists and palaeontologists to piece together the human family tree.

The scientific paper: “Human Remains from the Pleistocene-Holocene Transition of Southwest China Suggest a Complex Evolutionary History for East Asians” by Curnoe et al published in PLoS One.

For models and replicas of Neanderthals: CollectA Prehistoric Life Models.

Fossilised Fleas Ten Times the Size of a House Flea from the Jurassic

Warning, reading the current edition of “Nature” may lead to an outbreak of scratching as this scientific journal carries details of a new study into the evolution of fleas, with a focus on giant blood-sucking parasites from the Middle Jurassic.  Scientists have been studying prehistoric fleas that fed by sucking the blood of dinosaurs.

Dinosaurs

Chinese scientists have been slowly and surely piecing together the origins of the flea family using fossils found in two regions of China, famous for their dinosaur fossils.  Professor Huang Diying from Nanjing Institute of Geology and Palaeontology, (Chinese Academy of Sciences) and his colleagues have been “scratching” around in the sedimentary layers of Liaoning Province and in Ningcheng County collecting beautifully preserved, ancient, insect specimens that shed light on the origin and evolution of fleas.

The team have produced a scientific paper which details their studies.  It is entitled  “Diverse transitional giant fleas from the Mesozoic era of China”, not the catchiest of titles, but we know that many readers will be just “itching” to learn more about the team’s fossil discoveries.

Prehistoric Fleas

Fleas are one of the most dramatically specialised of all the families that make up the Order Insecta.  They have reduced wings, a laterally-flattened body and specialised mouth parts for feeding on the blood of mainly mammals (including our own species).  There are about 2,500 species or sub-species known and they are present throughout the world.  Most fleas are small, usually between 1-3 millimetres in length.  Fleas are ectoparasitic insects – insects that feed on other creatures (parasites).

Like most insects, fleas are seldom preserved as fossils.  Indeed, take away those fossils of insects preserved inside amber and you are left with a disproportionately sparse fossil record for such an important group of arthropods.  Definitive fossil evidence of fleas has been largely confined to fossils of fleas caught in tree sap and preserved as amber.

Dating from the Cenozoic

Most of these fossils date from the Cenozoic, from after the time of the dinosaurs, but in one or two exceptional locations fossils of fleas that once plagued the dinosaurs can be found.  The evidence suggesting the origin and early evolution of fleas has not been gathered together and studied, there simply were not enough fossils to study – until now.

One of the few records of a fossilised flea-like creature was unearthed in Australia a few years ago.  Found in sediments dated to around 120 million years ago (Early Cretaceous – Aptian faunal stage).  The genus was named Tarwinia, but it is difficult to work out the taxonomic relationship between this fossil and extant species.

Chinese Scientists Study Flea Fossils

Over the last few years, the Chinese scientists have  found several giant flea fossils dating from the Middle Jurassic (Bathonian faunal stage – Daohugou biota) in Ningcheng County, Inner Mongolia.  These insects lived around 165 million years ago.  The team have also uncovered the fossils of later specimens of the flea family near to Beipiao City, Liaoning Province.  This part of China is famous for its feathered dinosaur fossils and birds.  It seems that some of these blood-sucking insects may have adapted to a life living off the feathered dinosaurs.  These Early Cretaceous fossils relate to the famous Jehol biota (dated to around 125 million years ago).

This Chinese research provides new insights into the origin and early evolution of fleas and provides clues as to how these insects adapted as dinosaurs, birds and mammals evolved.  This new research pushes back in the fossil record the earliest occurrence of fleas (Order Siphonaptera) by about forty million years.

Mesozoic Fleas

The Mesozoic fleas like the sauropods these animals may have fed on; are huge.  Their bodies are many times bigger than extant fleas with many approximately 15 mm in length, and some longer than 20 mm, that’s ten times the size of a house flea.  As with flea species found today, the ancient females are larger than males.

For example, a flea species from Daohougou is 14 mm for female and only 8 mm for male.  They are wingless insects, but more or less dorso-ventrally flattened, their antennae are short and compact with more antennal segments (16-19 segments) than modern fleas (11 segments).  These prehistoric giants had a very long piercing siphonate mouthpart, elongate legs armed with various ctenidia (comb-like structures for securing themselves to their host).

Interestingly, these Mesozoic fleas show no signs of the modified back legs that permit these creatures to jump phenomenal distances.  It seems the ability to jump, is a Cenozoic development – at least based on the fossil evidence found so far.

Examining the Mouthparts

A close examination of the fossilised mouthparts of these ancient parasites show that many of the earliest forms have long, piercing mouthparts resembling those seen in the Mecoptera, an order of winged, graceful insects that include the scorpion flies.  Based on the fossil evidence it could be suggested that fleas should not be classified separately (Siphonaptera), but should be regarded as highly specialised members of the Mecoptera.

The fossils of the fleas when reviewed as a collection provides evidence that fleas readily adapted to take advantage of the food resources available from newly evolved, potential hosts such as the Dinosauria, early mammals and the Aves.

Fossils from Jehol, show fleas armed with various ctenidia on their legs and numerous posteriorly-directed setae (bristles) on their abdomens, indicating an adaption to hosts with hair or fur.  From the same strata, a number of mammal species have been described, the flea fossils show adaptations suited to feeding off animals covered in fur or hair.  The long siphon seen on some flea fossils dating from this period (120 million years ago) may have evolved so that they could be used to pierce the skin of feathered dinosaurs.

New Chinese Research

This new Chinese study may shed light on an amazingly fossilised insect found preserved in the soft mud of an ancient Mesozoic lake in Russia.  A 2.5-cm-long fossil of an insect was discovered in the Cretaceous aged rocks of Transbaikalia (eastern Russia).  This creature had no discernible wings, long legs with hooks on the end and a distended mouthpart, like a long proboscis.  The body was soft but could have expanded considerably in size, perhaps as a result of feeding on fluids such as blood.

The creature was named Saurophthirus longipes.  It has been suggested that this insect specialised in feeding upon the blood of pterosaurs (flying reptiles), a sort of ecological niche similar to that occupied by the bat fleas that feed on bats today.  Professor Huang Diying and his colleagues suggest that S. longipes may have been a specialised flea, highly adapted to a life feeding on reptile aviators.

For models and replicas of dinosaurs and pterosaurs: PNSO Age of Dinosaurs Models.

Dinosaurs

The Jurassic-aged fossils may be the earliest evidence of the flea family discovered to date and these fossils taken in context with the Cretaceous-aged finds show that Mesozoic fleas readily adapted to feeding on a number of vertebrate hosts, including in all likelihood the dinosaurs.

In recent years, there has been a number of studies published on fossils of other parasites that may have plagued the Dinosauria and the Pterosauria, blood-sucking lice for example.  To read an article on prehistoric lice that may have fed on both feathered and non-feathered dinosaurs: The Itchy and Scratchy Show.

Pebble May Be the Oldest H. sapiens Artwork Ever Found

A small pebble made of ochre, discovered in South Africa may be the oldest example ever found of an engraving made by H. sapiens.  Researchers from the University of Witwatersrand Institute for Human Evolution (S. Africa) have dated this eight-centimetre-long fragment, part of what was believed to be a much larger object, to around 100,000 years ago, making this object a candidate for the oldest known abstract art.

The colourful pebble was found in the Klasies River Cave (Eastern Cape Province), it is associated with human remains and artefacts from the Middle Stone Age.  The Middle Stone Age, the Mesolithic is the period of geological time used by archaeologists to describe the period of human evolution from the ending of the Ice Age phases to the beginning of sedentary farming.  It is a “catch all” period with different dates ascribed to Mesolithic artefacts and human remains dependent on where in the world they were found.

Commenting on the research, co-author of the scientific paper, Riaan Rifkin (University of Witwatersrand’s Institute for Human Evolution) stated:

“Associated human remains indicate that the engraved piece was certainly made by Homo sapiens.”

Rifkin and colleagues Francesco d’Errico and Renata Garcia Moreno performed extensive non-invasive analyses of the object.  Methods like X-ray fluorescence and microscopic analysis enabled the researchers to examine every minute detail of the ochre pebble.  The scientists have concluded that humans or a human deliberately and intentionally made sub-parallel cuts on the pebble – for what purpose remains open to speculation.

The Ochre Pebble – Does is Show Early Human Symbolism?

The pebble with the scratches highlighted.

Picture credit: University of Witwatersrand

Riaan added:

“Upon engraving the piece with a sharp lithic implement [stone tool], it is likely to have produced a markedly bright and dark red-maroon powder.  The design may therefore have been strikingly visible shortly after it was produced.”

Ochre- is a naturally tinted clay that mainly consists of hydrated iron oxide.  It was amongst the earliest pigments used by humans and other hominids (Neanderthals for example).  It is often referred to as the “caveman’s crayon”.

The Klasies River object contains a series of seven deep cuts and several (sixteen or so), smaller and somewhat shallower linear features.  It is not known whether the cuts of different magnitude were made by the same person or by different stone tools or made by a second human engraver.

Riaan commented:

“The fragment is a remnant of a formerly semi-circular ochre pebble that likely contained a much more extensive engraved design on its surface.”

The research team are particularly interested in whether or not the engraver or engravers made the design with symbolic intent.  Excavations at Blombos Cave, on the southern Cape Coast of South Africa have revealed similar finds of red ochre engraved with geometric patterns.  These objects have been dated to approximately 73,000 years ago, but the Klasies River Cave object is much older.

Use of symbols and meaningful images are thought to have been a significant breakthrough in human development. Language, maths and countless other studies are tied to this basic skill, in addition to improved communication.  To this day, art permits communication of identity and other things among diverse cultures.

Linear and cross-hatch carved patterns may have been common in Mesolithic culture.  As well as the examples found in Blombos Cave, scientists found similar carvings on ostrich eggshell fragments found in the Diepkloof Rock Shelter in the Western Cape Province.  Some of these, and other, similar objects may even pre-date the Klasies River pebble, but studies on them are ongoing and research papers yet to be published.

Riaan Rifkin explained:

“The employment of red ochre for symbolic purposes likely played an important role in mediating increasingly complex social relations that emerged during the Middle Stone Age.”

Christopher Henshilwood, a researcher at the University of Witwatersrand, did not work on this study, but he has examined other very early probable engravings.  For example, he studied abstract markings of another piece of southern African ochre dating to around 70,000 years ago.

In that case, the engraving consisted of a more complex geometric pattern that looks like the letter “X” repeated in a connected series.  Scientists remain puzzled as to what meaning these symbols may have had.

Henshilwood stated:

“They are symbols that I think could have been interpreted by those people as having meaning that would have been understood by others.”

At present, Rifkin and his team are studying 30,000-year old cave art from Africa.  So far, they have determined that the abstract images depict a zebra, a rhino and a half human-half cat creature – perhaps a deity symbol or an animal that features in tribal stories.  The Klasies River Cave system was inhabited by humans for thousands of years.  Excavations have been on-going at this location since the 1960s.  The site is one of the most important in the world in terms of H. sapiens evolution and development.  The artefacts found have provided an unprecedented insight into early human behaviour, particularly hunting among groups of early humans.  Some of the remains and items found in the cave system are believed to date from more than 125,000 years ago.

Visit Everything Dinosaur’s website: Everything Dinosaur.