Jaw Fossil Indicates Denisovans Occupied the Tibetan Plateau

Denisovans, occupied the Tibetan Plateau long before Homo sapiens arrived in the region.  Furthermore, the ability to cope with less oxygen at high altitudes may have been passed onto our species when ancient members of Homo sapiens, bred with Denisovans.  The analysis of a fragmentary lower jaw bone reveals the presence of Denisovans at least 160,000 years ago at the Baishiya Karst Cave complex in Xiahe, China.

The ability to survive in such extreme climates had been thought to be a unique trait of H. sapiens, that is now not the case and what is more, the enigmatic and poorly known Denisovans seem to have passed on a gene that helps modern people cope with living at high elevations.

A Digital Reconstruction of the Fossil Mandible

Picture credit: Jean-Jacques Hublin (MPI-EVA)

The Enigmatic Denisovan People

The study, undertaken by a team of international researchers including Shara Bailey (New York University), as well as scientists from the Institute of Tibetan Plateau Research, the Chinese Academy of Sciences, Lanzhou University, and the Max Planck Institute for Evolutionary Anthropology, has been published in the journal “Nature”.

Using a technique known as ancient protein analysis, the researchers found that the mandible’s (lower jaw) owner belonged to a Denisovan population from Siberia.  This population occupied the Tibetan Plateau, regarded as the “Roof of the World” because it rises three miles (five kilometres), above sea level.  This suggests that the enigmatic Denisovans were adapted to a low oxygen environment.

In contrast, evidence of Neanderthals is rarely found above 2,000 metres and what evidence there is, probably indicates that Homo neanderthalensis populations only occasionally climbed to such heights, perhaps for the purpose of a special hunt or ceremony.  They do not seem to have persisted at high altitude.

The research team state that Denisovans had already adapted to living in this high-altitude setting significantly prior to the appearance of Homo sapiens.  Previous genetic studies found present-day Himalayan populations carry the EPAS1 allele in their genome, passed on to them by Denisovans, which helps with adaptation to their specific and demanding environment.

A Posterior View of the Fossil Mandible

Picture credit: Jean-Jacques Hublin (MPI-EVA)

Who Were the Denisovans?

Denisovans are members of a hominin group currently only known directly from fragmentary fossils, the genomes of which have been studied from a single site, Denisova Cave in Siberia.  They are also known indirectly from their genetic legacy through gene flow into several low-altitude East Asian populations and high-altitude modern Tibetans.  The presence of a new species of ancient human was confirmed when a research team led by Svante Pääbo from the Max Planck Institute for Evolutionary Anthropology (MPI-EVA), conducted a genetic study on a single fossil finger bone from the Denisova Cave site.

To read an article from 2010 that summarises the Max Planck Institute for Evolutionary Anthropology research: Finger Bone Hints at New Species of Hominin.

Commenting on the significance of linking a fossil to the Tibetan Plateau, one of the paper’s co-authors Jean-Jacques Hublin (MPI-EVA), stated:

“Traces of Denisovan DNA are found in present-day Asian, Australian, and Melanesian populations, suggesting that these ancient hominins may have once been widespread.  Yet, so far, the only fossils representing this ancient hominin group were identified at the Denisova Cave.”

Indeed, Everything Dinosaur published a report back in 2016 that linked the Inuit people of the Arctic to a Denisovan ancestry: Extinct Human Cousin Helped the Inuit Survive.

A Photograph of the Actual Fossil Jaw Bone (Lateral View)

Picture credit: Dongju Zhang (Lanzhou University)

Discovered by a Monk

In this newly published paper, the researchers describe a hominin lower mandible that was found on the Tibetan Plateau in the Baishiya Karst Cave in Xiahe, Gansu Province, China.  The fossil was originally discovered in 1980 by a local monk who donated it to the 6th Gung-Thang Living Buddha who then passed it on to Lanzhou University.

Since 2010, researchers Fahu Chen and Dongju Zhang from Lanzhou University have been studying the cave site from where the mandible originated in a bid to find more human remains.  In 2016, a collaboration began with the Department of Human Evolution at the Max Planck Institute for Evolutionary Anthropology and although no DNA has been recovered, the team did manage to extract proteins from one of the large molars within the jaw.  These proteins were then categorised using a technique called ancient protein analysis.

The Reconstructed Denisovan Jaw Bone

Picture credit: Jean-Jacques Hublin (MPI-EVA)

Piecing Together the Face of a Denisovan

The fossil record of the Denisovans is particularly sparse, it is limited to just some teeth and part of a finger.  This is the first fossil of its kind to be found and perhaps, if more Denisovan fossils can be discovered, then it hints at the possibility that anthropologists might be able to reconstruct the skull.

Co-author Shara Bailey explained:

“Although we still do not know the shape and size of the Denisovan skull, now with a lower jaw we can start to piece together the puzzle of what they actually looked like”.

Everything Dinosaur acknowledges the assistance of a press release from New York University in the compilation of this article.

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Callichimaera perplexa et al Challenging the Definition of a Crab

An international team of scientists reported the discovery of a variety of Late Cretaceous marine crustacea that have challenged the current definitions of what makes a crab.  It is a case of a Cretaceous crab ruffling a few scientific feathers.

Writing in the academic journal “Science Advances”, the researchers from the University of Alberta, Kent State University, the University of Montreal, the Smithsonian Tropical Research Institute in Panama, the Canadian Parks and Wilderness Society, the National Autonomous University of Mexico, the University of Nevada, and the College of Communication and Design in Boca Raton, Florida, as well as Yale University , describe the discovery of hundreds of beautifully-preserved specimens from the USA and Colombia.

A Life Reconstruction of the Cretaceous Crab  Callichimaera perplexa

Picture credit: Elissa Martin, (Yale Peabody Museum of Natural History)

The preserved remains include hundreds of tiny shrimp fossils and an entirely new branch of the evolutionary tree for crabs (Order Decapoda).

A Very “Goofy-looking” Crab – Callichimaera perplexa

According to lead researcher, Yale University palaeontologist Javier Luque, the most significant fossil discovery is Callichimaera perplexa, which at around 95-million-years-old, is the earliest example of a swimming arthropod with paddle-like legs since the eurypterids (sea scorpions), that are believed to have died out in the Permian.  The genus name derives from the mythical creature called a chimera, which was formed from the body parts of a variety of different animals.  In a press release from Yale University, it is stated that the binomial scientific name translates as “perplexing beautiful chimera.”

Examining a Fossil Specimen (Callichimaera perplexa)

Picture credit: Yale University

A Unique and Very Strange Cretaceous Nektonic Crab

Measuring around 2-3 centimetres in diameter, Callichimaera is described as looking very strange with large, unprotected compound eyes with no sockets, bent claws, leg-like mouth parts, a long body and an exposed tail.  It was nektonic (an active swimmer), as an adult it resembled typical crab larval stages.  This suggests that some ancient crabs may have retained a few of their larval traits into adulthood, amplified them, and developed a new body architecture.  This is an evolutionary process called “heterochrony” – a change to the timing or rate of development relative to the ancestor.

The Diverse Body Plans of Swimming Crabs and other Nektonic Arthropods

Picture credit: Yale University

Luque commented:

“Callichimaera perplexa is so unique and strange that it can be considered the platypus of the crab world.  It hints at how novel forms evolve and become so disparate through time.  Usually we think of crabs as big animals with broad carapaces, strong claws, small eyes in long eyestalks, and a small tail tucked under the body.  Well, Callichimaera defies all of these ‘crabby’ features and forces a re-think of our definition of what makes a crab a crab.”

A Computer-generated Image Showing the Underside of Callichimaera perplexa

Picture credit: Yale University

The scientific paper: “Exceptional Preservation of mid-Cretaceous Marine Arthropods and the Evolution of Novel Forms via Heterochrony” by J. Luque1, R. M. Feldmann, O. Vernygora, C. E. Schweitzer, C. B. Cameron, K. A. Kerr, F. J. Vega, A. Duque, M. Strange, A. R. Palmer and C. Jaramillo published in the journal Science Advances.

Everything acknowledges the assistance of a press release from Yale University in the compilation of this article.

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Simbakubwa kutokaafrika – Giant African Hyaenodont

Scientists writing in the “Journal of Vertebrate Paleontology” have described a new species of giant hyaenodont from sub-Saharan Africa that was bigger than a polar bear.  The giant carnivore, most likely the apex predator in its Early Miocene ecosystem, has been named Simbakubwa kutokaafrika and this fearsome beast with its huge teeth is the stuff of nightmares.

A Life Reconstruction of the Newly Described Giant Hyaenodont Simbakubwa kutokaafrika

Picture credit: Mauricio Anton

Simbakubwa kutokaafrika – A Chance Discovery

Co-author of the scientific paper Matthew Borths (Duke University, North Carolina), was visiting the Nairobi National Museum in Kenya in 2013  to view some specimens.  He asked to view the contents of a collection labelled as “hyaenas” and he discovered a gigantic lower jaw bone more than forty centimetres in length.   The bones and teeth had been placed in a drawer after a dig in western Kenya in the late 1970s and had remained there ever since.

The genus name, Simbakubwa is from Swahili “simba” meaning “lion” and “kubwa” meaning “big”, big this animal certainly was, its body weight has been estimated at over 1,500 kilograms making S. kutokaafrika heavier than the largest land carnivore alive today, the polar bear (Ursus maritimus).  The species name kutokaafrika, is also from Swahili, it means “from Africa”.

The Lower Jaw of S. kutokaafrika Compared to the Jaw of a Modern Lion (Panthero leo)

Picture credit: Journal of Vertebrate Paleontology

The picture (above), shows the holotype left dentary (KNM-ME 20A), in (A) lingual, (B) buccal and (C) occlusal views.  It is compared in size to the lower jaw of a modern lion (Panthero leo), photograph (D).  Note the scale bar is 5 cm.

Classified as a Member of the Hyaenodonta (Hyainailourinae)

The carnivore has been classified as a member of the Hyaenodonta (Hyainailourinae), a large and diverse group of creodonts that may have evolved in Africa.  These animals dominated predatory niches in ecosystems until the emergence of the modern Carnivora.  As such, Simbakubwa is only very distantly related to today’s big cats the Felidae.

The Giant Teeth of a Giant Prehistoric Predator

Picture credit: Journal of Vertebrate Palaeontology

The photograph (above), shows isolated teeth associated with the lower jaw.  Pictures (A, B and C) show a right lower canine in lingual, buccal and occlusal views.  A right molar (m1), is shown in (D) occlusal, (E) lingual and (F) buccal views and the second right molar (m2), is shown in (G) occlusal, (H) lingual and (I) buccal views, whilst a left molar (m2), is show in (J) occlusal, (K) lingual and (L) buccal views.  Note the scale bar equals 5 cm.

A Widely Dispersed Clade of Super-sized Mammalian Predators

The hyainailourine hyaenodonts are among the biggest land mammalian carnivores known to science.  The group is temporally and geographically widely dispersed with fossil finds in Europe, Asia, North America, Arabia as well as Africa.  The fossil material assigned to the Simbakubwa genus represent the most complete hyainailourine known from sub-Saharan Africa.  The researchers conclude that the fossils represent a relatively young adult animal and the material was collected at the Meswa Bridge site (western Kenya).

Bayesian ancestral state reconstruction supports an Afro-Arabian origin for Hyainailourinae with subsequent dispersal to Europe and Asia.  A regression analysis conducted by the authors of the paper, based on carnassial size suggests that Simbakubwa could have weighed around 1,500 kilogrammes, more than four times the weight of a modern African lion.   The evolution and extinction of Hyainailourinae offers important insights for interpreting ecological transitions from Paleogene to Neogene faunas in Afro-Arabia and Eurasia.

The scientific paper: “Simbakubwa kutokaafrika, gen. et sp. nov. (Hyainailourinae, Hyaenodonta, ‘Creodonta,’ Mammalia), a gigantic carnivore from the earliest Miocene of Kenya” by Matthew R. Borths and Nancy J. Stevens published in the Journal of Vertebrate Paleontology.

For models and replicas of prehistoric animals: The Everything Dinosaur Website.

Tentacled “Cthulhu” Fossil Reveals Relative of Modern Sea Cucumbers

The remarkable Silurian-aged deposits located at a secret site in Herefordshire (England), have provided scientists with a unique look at the early evolution of sea cucumbers and their relatives.  The rocks at this location are comprised of very fine grained volcanic ash that settled on the seafloor some 430 to 425 million years ago.  These deposits have preserved in fantastic detail the remains of the marine biota.  The latest new species to be named from this location is Sollasina cthulhu, a multi-tentacled, benthic animal that was a ferocious predator.

The prehistoric sea cucumber’s trivial name honours the “Cthulhu” universe, as it resembles some of the monsters created by the American, 20th century science-fiction writer H. P. Lovecraft.  At only three centimetres across, it might not look very formidable to us, but its numerous tentacles, (actually tube feet), would have been used to terrorise and capture other animals as it roamed across the seafloor.

A Life Reconstruction of the Newly Described Sollasina cthulhu

Picture credit: Elissa Martin, (Yale Peabody Museum of Natural History)

Writing in the academic journal the “Proceedings of the Royal Society B (Biology)”, palaeontologists from the USA and the UK were able to create an accurate, three-dimensional digital reconstruction of the 430-million-year-old fossil.  The exceptionally preserved fossil, once analysed using this three-dimensional computer modelling technique, revealed details of internal soft tissues previously not seen in a fossil like this.

Sollasina cthulhu

Like other fossils from the secret Herefordshire “Lagerstätte”, Sollasina cthulhu was examined using a method that involved grinding it away, layer-by-layer, with a photograph taken at each stage.  This led to hundreds of images being produced which were then combined in a special computer programme to create an exact 3-D image, a “virtual fossil”.

The scientists, which included researchers from the Oxford Museum of Natural History, Leicester University, Imperial College London, Yale University and the University of Southern California, were able to make out an internal ring, which is believed to be part of the organism’s water vascular system.  The water vascular system is the system of fluid-filled canals used for feeding and movement in living sea cucumbers and their relatives.

Dr Imran Rahman (Deputy Head of Research at Oxford University Museum of Natural History) and lead author of the paper stated:

“Sollasina belongs to an extinct group called the ophiocistioids, and this new material provides the first information on the group’s internal structures.  This includes an inner ring-like form that has never been described in the group before.  We interpret this as the first evidence of the soft parts of the water vascular system in ophiocistioids.”

Computer-based Analysis

This new fossil was subjected to a phylogenetic analysis to assess the evolutionary relationships between fossil sea cucumbers and sea urchins (members of the Echinodermata Phylum).  The results showed that Sollasina and its relatives are more closely related to sea cucumbers than they are to sea urchins.  This has provided a new insight into the evolution of this very important group of invertebrates.

A Computer-generated Three-dimensional Image of Sollasina cthulhu

Picture credit: Dr Imran Rahman (Oxford University Museum of Natural History)

Dr Jeffrey Thompson (University of Southern California) and a co-author of the paper commented:

“We carried out a number of analyses to work out whether Sollasina was more closely related to sea cucumbers or sea urchins.  To our surprise, the results suggest it was an
ancient sea cucumber.  This helps us understand the changes that occurred during the early evolution of the group, which ultimately gave rise to the slug-like forms we see today.”

The Herefordshire site has provided palaeontologists with some remarkable fossils to study:

An ancient Silurian ostracod: An Ancient Ostracod from Herefordshire.

A rare Silurian marine worm: Rare Silurian Fossil Worm from a Herefordshire “Hotspot”.

A Prehistoric Scene – Life in the Silurian Seas

Picture credit: Everything Dinosaur

Everything Dinosaur acknowledges the assistance of a press release from the Oxford University Museum of Natural History in the compilation of this article.

The scientific paper: “A New Ophiocistioid with Soft-tissue Preservation from the Silurian Herefordshire Lagerstätte, and the Evolution of the Holothurian Body Plan” by Imran A. Rahman, Jeffrey R. Thompson, Derek E. G. Briggs, David J. Siveter, Derek J. Siveter and Mark D. Sutton published in the Proceedings of the Royal Society B.

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