A remarkable new study suggests that Homo erectus populations in East Asia may have co-existed and interbred with Denisovans hundreds of thousands of years ago. The research provides the first molecular evidence linking these ancient human lineages.  This recently published research demonstrates how new protein recovery and analysis techniques can enhance data retrieved in association with hominin fossil discoveries.

The paper, published in the journal “Nature”, analysed fossil teeth from China dating to around 400,000 years ago (Chibanian stage of the Pleistocene Epoch). Scientists extracted ancient proteins preserved inside the dental enamel. As a result, they uncovered genetic clues that may reshape our understanding of human evolution in Asia.

Ancient Proteins from Fossil Teeth

The researchers studied six Homo erectus teeth from three famous Chinese fossil sites. These included Zhoukoudian, the home of “Peking Man”. Zhoukoudian on the North China Plain is now a UNESCO World Heritage site.  The Pliocene and Pleistocene deposits have preserved the remains of early hominins, and the site has been the focus of intense research.

“Peking Man” is thought to represent a sub-species of Homo erectus.  A fossil tooth discovered in 1921 and subsequent hominin fossil discoveries has helped palaeoanthropologists to re-define aspects of hominin evolution. For example, H. erectus is thought to be a direct ancestor of modern humans (H. sapiens).  In addition, whilst it is thought that Homo erectus originated in Africa, it was the first hominin to migrate extensively, with fossil remains found throughout Asia.

Importantly, the team used palaeoproteomics (the study of ancient proteins), rather than ancient DNA analysis. Ancient DNA rarely survives in fossils this old. However, proteins locked within tooth enamel can persist for far longer.

The scientists identified two unusual amino acid variants in a tooth-development protein called ameloblastin. One variant appears unique to East Asian Homo erectus. The second variant proved even more intriguing. Previously, it had only been identified in Denisovans.  The Denisovans are an enigmatic and poorly known archaic hominins that lived in Asia during the middle to late Pleistocene. They are named after the Denisova Cave in the Altai Mountains of Siberia, Russia, where their fossils were first discovered in 2008.

To read an article from 2013 highlighting research into the Denisovans: The Mystery of the Denisovans.

Evidence of Ancient Interbreeding?

The shared protein variant hints that Homo erectus and Denisovans may have interbred in East Asia. If correct, this would add another layer of complexity to the human evolution story. Palaeoanthropologists have long suspected that ancient human species interbred with one another. For example, analysis of other hominin fossil discoveries revealed modern humans interbred with both Neanderthals and Denisovans. Moreover, traces of Denisovan ancestry survive in some living populations today, especially in Southeast Asia and Oceania.

Now, this study suggests that these ancient interactions may have started much earlier than previously thought.

Models depicting three hominins. Homo erectus (left), H. neanderthalensis (centre) and a modern human (H. sapiens) right. The Homo erectus is holding a flaming stick a reference to their tool making abilities and control of fire.

The image (above) shows three figures that help to illustrate hominin evolution.  The Homo erectus figure reflects the control of fire that this species is thought to have possessed.  The models come from an “Evolution of Man” model set produced by Safari Ltd.

To view the range of prehistoric figures including early hominins available: Prehistoric World Figures.

A Complicated Human Family Tree

Scientists know that several human lineages overlapped across Africa and Eurasia during the middle to late Pleistocene. However, their exact relationships remain poorly understood. This new research adds more evidence that ancient humans did not evolve in isolated branches. Instead, different populations probably met and exchanged genes repeatedly.

Interestingly, some researchers now wonder whether certain Chinese fossils traditionally assigned to Homo erectus might actually belong to Denisovan-related groups.

A new species of hominin Homo longi: “Dragon Man” from North-eastern China.

Hominin Fossils Still Hold Molecular Secrets

The study also highlights the growing importance of protein analysis in palaeoanthropology. Recovering DNA from hominin fossil remains extremely difficult. Nevertheless, palaeoproteomics is providing new perspectives on human evolution.  Ancient proteins recovered from hominin teeth may provide evidence to help scientists to better understand human evolution.

As more fossils undergo molecular analysis, researchers may finally untangle the complicated evolutionary history of ancient humans in Asia. Furthermore, how our own species evolved and its complex taxonomic relationship with other hominin taxa.

For now, these ancient teeth provide tantalising evidence that Homo erectus and Denisovans once shared more than just the same landscape. They may also have shared genes.

The scientific paper: “Enamel proteins from six Homo erectus specimens across China” by Qiaomei Fu, Zhongyou Wu, E. Andrew Bennett, Song Xing, Qiang Ji, Zhe Dong, Huiyun Rao, Xuejun Gu, Yizhao Dang, Jun Xing, Kai Zhou and Xiaotian Feng published in the journal Nature.

For scientifically accurate models of ancient hominins and other Pleistocene fauna: Models of Prehistoric Life.

A new genus of sauropod dinosaur has been named from Brazil.  It expands the known diversity of Early Cretaceous sauropods in the northern part of South America. In addition, the newly named dinosaur Dasosaurus tocantinensis provides fresh evidence of dinosaur dispersal between Europe, Africa and South America. The scientific paper describing the new taxon was recently published in the “Journal of Systematic Palaeontology”.

Dasosaurus tocantinensis

The fossil material was discovered by a construction team building a road/rail terminal in the city of Davinópolis, Maranhão state (northeastern Brazil).  The fossils consisted of ten disarticulated caudal vertebrae, limb bones, ribs, a pubis, ischium and several phalanges were found at the bottom of an eight-metre-high slope.  Initially, it was thought these large bones were Quaternary in age.  However, it was soon determined that the material represented a large sauropod dinosaur.

Palaeontologists have confirmed that the fossils (specimen number CPHNAM VT 1600), are from the Aptian-aged strata of the Itapecuru Formation. At an estimated twenty metres in length, Dasosaurus is the largest sauropod to be scientifically described from this formation. Moreover, it is one of the largest dinosaurs known from Brazil.

Dasosaurus has been assigned to the Somphospondyli, a group of titanosauriform sauropods closely related to titanosaurs. Scientists identified several unique anatomical traits in the fossil material. These included unusual ridges on the tail vertebrae and a pronounced lateral bulge on the femur.

A scale drawing of the Brazilian titanosauriform Dasosaurus tocantinensis. Picture credit: Everything Dinosaur (AI assisted).

Picture credit: Everything Dinosaur (AI assisted)

What’s in a Name?

The genus name combines the Greek word “dasos”, meaning forest, with “sauros”, meaning lizard. It is in recognition of this region of Brazil is famous for the remarkable Amazon forest. The species name honours the Tocantins region, close to where the fossils were discovered.

The study highlights an intriguing evolutionary relationship.  Phylogenetic analysis brackets Dasosaurus with the larger, and geologically older Garumbatitan morellensis, a sauropod from the Arcillas de Morella Formation of Spain. As a result, the scientists proposed that the lineage originated in Europe. Subsequently, these dinosaurs dispersed into South America through northern Africa before the Atlantic Ocean fully opened.

This discovery highlights important faunal links between Europe and Gondwana during the Early Cretaceous. In addition, it demonstrates that dinosaur populations could still migrate between landmasses during the Early Cretaceous.

Studying Dinosaur Bone Histology

The research team also examined the microscopic structure of the fossil bones. This branch of palaeontology is known as osteohistology. The scientists identified a mixture of primitive and more advanced traits within the bone tissue. These findings provide valuable information about sauropod growth and development. Moreover, they help scientists understand the evolutionary transition between early neosauropods and later titanosaurs.

The Significance of Dasosaurus tocantinensis

South America has yielded many spectacular sauropod fossils.  For example, some of the largest dinosaurs of all time such as Argentinosaurus and Patagotitan.  However, discoveries of earlier branching titanosauriforms remain relatively rare.

To read about the discovery of the giant titanosaur Patagotitan: A New Giant Dinosaur Gets a Name.

An enormous titanosaur from Brazil Austroposeidon magnificus: Huge Titanosaur from Brazil (Austroposeidon).

Dasosaurus tocantinensis helps fill an important gap in the fossil record. It also expands the known diversity of Brazilian sauropods from the Early Cretaceous. Furthermore, the discovery supports the idea that ancient dinosaur faunas remained interconnected across vast regions. During the Early Cretaceous, Europe, Africa and South America still shared intermittent land connections. These routes allowed dinosaurs and other animals to disperse between continents.

The known dinosaur biota associated with the Itapecuru Formation of Brazil. Picture credit: Everything Dinosaur (AI assisted).

Picture credit: Everything Dinosaur (AI assisted)

With its distinctive anatomy and European affinities, Dasosaurus tocantinensis represents one of the most significant South American sauropod discoveries announced this year.

The scientific paper: “A new titanosauriform with European affinities in the Early Cretaceous of Brazil: insights on Somphospondyli phylogeny, histology and biogeography” by Elver L. Mayer, Julian C. G. Silva Junior, Leonardo R. Kerber, Bruno A. Navarro, Kamila L. N. Bandeira, Juan C. Cisneros, Eliane P. Sousa, Agostina A. Pereira, Manuel A. Medeiros, Rafael M. Lindoso, Francisco Pedro Cavalcanti Neto, Aline M. Ghilardi, Tito Aureliano, Pedro L. Godoy, Gabriel S. Ferreira and Max C. Langer published in the Journal of Systematic Palaeontology.

The multi-award-winning Everything Dinosaur website: Models of Sauropods and Other Prehistoric Animals.

A newly published scientific paper has provided fresh insights into the feeding habits of the famous hadrosaur Maiasaura peeblesorum. Analysis of tooth wear in juvenile Maiasaura compared to adult hadrosaurs suggests that young Maiasaura fed differently from fully grown animals. Researchers examined dental wear associated with Maiasaura peeblesorum fossil teeth.  Dietary insights may help to explain the remarkable success of these ornithischian dinosaurs.

The study focused on the microscopic wear patterns preserved in the dental batteries. Hadrosaurs possessed hundreds of tightly packed teeth. These teeth formed highly efficient grinding surfaces. However, the new research indicates that juveniles used their teeth differently when compared to adult duck-billed dinosaurs.

Haolonggood Maiasaura models. Each adult figure is supplied with a juvenile. The green coloured adult Maiasaura (left) is called Chun Hui. Whereas the model with the tail tinged purple is known as Hua Di. Research suggests that young Maiasaura may have had a different diet compared to the adults.

The image (above) shows the adult and juvenile Maiasaura models available from Haolonggood.  These figures have been praised for their scientific accuracy.

To view the range of Haolonggood figures available: Haolonggood Prehistoric Animal Models.

A Different Diet for Young Hadrosaurs?

The researchers identified different proportions of wear types in juvenile jaws. This evidence suggests that young Maiasaura processed softer vegetation. In contrast, adults probably consumed tougher and more fibrous plants. Consequently, the study supports the idea of an ontogenetic dietary shift. In simple terms, the diet changed as the dinosaur matured. This feeding strategy may have reduced competition between younger and older herd members. Therefore, juveniles and adults could share the same environment whilst exploiting different food resources. In addition, a less fibrous and more nutritious diet could have facilitated rapid growth.  Growing quickly is an effective way to avoid predation.

Duck-billed dinosaurs grew fast to avoid being eaten: Hadrosaurs Grew Fast to Avoid Predation.

The researchers postulated that the more nutritious diet probably consisted of new buds and protein-rich berries.  The extra calories consumed, especially the greater proportion of carbohydrates, fuelled their rapid growth and development.

Maiasaura peeblesorum “Good Mother Lizard”

Maiasaura peeblesorum ranks amongst the most famous dinosaurs discovered in North America. Palaeontologists uncovered extensive nesting colonies in the Upper Cretaceous deposits of Montana. These fossil sites included nests, eggs and juvenile skeletons. As a result, scientists proposed that Maiasaura cared for its young. It was named and scientifically described in 1979 (Horner and Makela). The genus name translates as “good mother lizard”. This duck-billed dinosaur measured around eight to nine metres in length when fully grown.  The jaws analysed in this study came from very young Maiasaura which measured around a metre in length. Maiasaura lived approximately 76 million years ago during the Late Cretaceous (Campanian faunal stage).

“Good Mother Lizard” A Maiasaura and nest. The human silhouette provides a scale. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Like other hadrosaurs, Maiasaura possessed a broad beak and sophisticated dental batteries adapted for processing plant material. Scientists also think these herbivores lived in large herds.

Studying Tooth Wear

The authors of the study are John P. Hunter (Ohio State University) and Christine M. Janis who is part of the Bristol Palaeobiology Group at the University of Bristol. They analysed wear facets preserved on the teeth. Different types of scratches and polished surfaces can reveal how animals processed their food. Furthermore, these microscopic traces help scientists infer diet and feeding behaviour. The authors concluded that juvenile Maiasaura displayed wear patterns distinct from adults. This difference probably reflects changes in feeding mechanics as the skull and jaws developed.

Understanding Dinosaur Growth and Behaviour

Scientists have studied Maiasaura extensively for decades. Previous research examined growth rates, nesting behaviour and herd structure. This new paper adds another important piece to the puzzle. Moreover, it demonstrates how dinosaur feeding strategies changed throughout life. Studies like this help palaeontologists reconstruct ancient ecosystems more accurately. They also show that dinosaur populations may have divided food resources according to age. Modern animals often display similar ecological separation.  For example, birds with altricial young and an extended nesting period often have different diets depending on their age.  Juveniles grow fast on a more nutritious diet of proteins, sugars and fat compared to the less nutritious diet consumed by the adult.

A Caveat

The researchers highlight that adult dental batteries of Maiasaura were not available for this study. However, as all other saurolophines examined have similarly large proportions of vertical wear on the dental batteries, while lambeosaurines appear to have a greater proportion of horizontal wear, they assume that the dental wear of adult specimens of Maiasaura would resemble that of these related saurolophine taxa.

The paper’s authors acknowledge this to be a weakness in their argument, and that their conclusions would be falsified if the dental batteries of adult Maiasaura were to resemble those of the juveniles. However, the researchers consider that, as with many other cases in paleobiology, it is still worthwhile proceeding with analysis on partial data if there are appropriate caveats placed on the limitations.

Commenting on the significance of this new Maiasaura peeblesorum fossil study, Mike from Everything Dinosaur stated:

“Hadrosaurs dominated many Late Cretaceous ecosystems. Their advanced chewing mechanisms helped them process huge quantities of vegetation. The new Maiasaura peeblesorum fossil teeth study highlights just how adaptable these herbivores may have been”.

The scientific paper: “Tooth wear in juvenile and adult hadrosaurs: implications for parental care in Maiasaura” by John P. Hunter and Christine M. Janis published in Palaeogeography, Palaeoclimatology, Palaeoecology.

The award-winning Everything Dinosaur website: Hadrosaur and Dinosaur Models.

Researchers from Virginia Tech (Virginia, USA) have identified a new species of Late Triassic dinosaur.  The dinosaur has been named Ptychotherates bucculentus.  This new carnivorous dinosaur taxon has been erected based on the detailed examination of an incomplete, well-preserved but jumbled up skull fossil (specimen number CM 31368).  The skull comes from the world-famous Coelophysis Quarry from the Ghost Ranch fossil site in New Mexico. Significantly, the scientists have assigned P. bucculentus to the Herrerasauria.  It might be one of the last surviving members of this earliest-evolving clade of meat-eating dinosaurs.

A New Herrerasaurian Dinosaur

In 1982, a field team from the Carnegie Museum of Natural History (Pittsburgh, Pennsylvania, USA), excavated the fossil from the Coelophysis Quarry. This site contains the preserved remains of numerous vertebrates, but the fossil assemblage is dominated by fossils of the theropod Coelophysis bauri. The fossil bones of over a thousand individuals have been reported. The skull remained in storage and was not studied. However, one of the paper’s authors Sterling Nesbitt (Department of Geosciences, Virginia Tech), arranged for the skull to be scanned using computer tomography (CT). The individual bones were identified and a 3D model of the skull constructed.

When digitally reconstructed the scientists discovered that the jugal bone was unusually tall. Ptychotherates has proportionately the dorsoventrally deepest jugal known for any Triassic-aged dinosaur. Phylogenetic analyses align Ptychotherates bucculentus with Tawa hallae, Chindesaurus bryansmalli and Daemonosaurus chauliodus within the Herrerasauria clade and closely related to the Herrerasauridae family.  The researchers erected the clade Morphoraptora to nest these dinosaurs in.  The Morphoraptora are united by several autapomorphies.  For example, these dinosaurs have extremely fine serrations on their teeth.

Artistic rendition of Ptychotherates bucculentus. Picture credit: Megan Sodano for Virginia Tech.

Picture credit: Megan Sodano for Virginia Tech

The Morphoraptora and Radiohead

Morphoraptora is from the Greek for “form”, “shape” and raptor for “robber”.  This reflects the morphological convergence between members of this clade and theropod dinosaurs.  It loosely translates as “body snatcher” a reference to the close anatomical similarities between the carnivorous Morphoraptora and the Theropoda.  In addition, it honours the 2007 song by the English rock band Radiohead in the album In Rainbows, which one of the authors of the study listened to whilst preparing the manuscript.

The open-access paper was published in the journal Papers in Palaeontology.

To read Everything Dinosaur’s blog post from 2009 about the discovery of Tawa hallae: New Meat-eating Dinosaur from the Chinle Formation.

Our 2011 post about the discovery of Daemonosaurus: The Little “Demon” of Ghost Ranch.

Ptychotherates bucculentus – What’s in a Name?

The skull of Ptychotherates (pronounced Tie-cho-the-rate-ees), was relatively short, but proportionately deep.  Although, no substantial postcranial material is known, scientists estimate that this dinosaur probably measured around 2.2 metres in length.  Like the closely related Tawa, Chindesaurus and Daemonosaurus, it was probably lightly built with the tail comprising around fifty percent of the total body length.

The genus name means “folded jaw hunter”.  This references the carnivorous nature of this dinosaur and also the “folds” and unusual orientations of the fossil material that hampered reconstruction. The species name is from the Latin and translates as “with full cheeks” in reference to the exceptionally tall jugal.

One of the co-authors of the study Simba Srivastava holding the preserved skull of Ptychotherates bucculentus. Picture credit: Spencer Coppage for Virginia Tech.

Picture credit: Spencer Coppage for Virginia Tech

A Late Triassic Hunter

The paper also notes that the phylogenetic relationships of these early saurischian dinosaurs remain controversial. Unfortunately, the fossil material ascribed to Ptychotherates bucculentus, Tawa hallae, Chindesaurus bryansmalli and Daemonosaurus chauliodus does not overlap sufficiently to permit direct fossil comparison. The lack of fossils makes determining the phylogeny difficult. However, the discovery of herrerasaurians in the Coelophysis Quarry establishes that different types of meat-eating dinosaur co-existed during the Late Triassic. Furthermore, the occurrence of morphoraptorans in the Coelophysis Quarry assemblage extends their stratigraphic range later in the Triassic than previously thought.

The exact age of Ptychotherates is hard to determine.  However, it is estimated that this lithe meat-eater lived more recently than 210 million years ago. Ptychotherates bucculentus may have lived shortly before the great extinction event that marked the end of the Triassic. Moreover, scientists have not found any younger herrerasaurian fossils. This discovery suggests that the mass extinction event may have wiped out this dinosaur lineage. In addition, palaeontologists have not found Late Triassic herrerasaurians anywhere else in the world. Therefore, the region that is now southwestern USA may have served as the clade’s final refuge before their extinction.

It had been thought that the end-Triassic extinction wiped out competitors to the Dinosauria.  However, with the discovery of Ptychotherates it suggests that some long-standing dinosaur lineages also died out at this time.

Everything Dinosaur acknowledges the assistance of a media release from Virginia Tech in the compilation of this article.

The scientific paper: “A new taxon of saurischian dinosaur from the Coelophysis Quarry of New Mexico, USA (Triassic: latest Norian or Rhaetian) highlights herrerasaurian diversity in the latest Triassic” by Simba Srivastava and Sterling J. Nesbitt published in Papers in Palaeontology.

The award-winning Everything Dinosaur website: Models of Triassic Dinosaurs and Prehistoric Animals.