Scientists have solved a five-decade-old mystery.  A strange bone found in 1974 has been identified as part of the pelvis from a Dimetrodon (D. teutonis).  In 1974, geologist Thomas Martens discovered a fossil bone whilst exploring the famous Bromacker fossil site in the Thuringian Forest near the village of Tambach-Dietharz (Germany).  This site consists of Permian-aged deposits that have yielded a treasure trove of fossils.  The Bromacker location is regarded as one of the world’s most important locations for fossils of Early Permian animals.  It is part of the UNESCO Geopark in the region, and the Lower Permian rocks have been extensively explored and mapped.

An aerial view of the famous Bromacker fossil site in Germany. Picture credit: Jakob Stubenrauch Team Drohne.

Picture credit: Jakob Stubenrauch Team Drohne

Fossil Mystery Solved at Bromacker Fossil Site

Prior to the fossil bone discovery, tracks of tetrapods had been found at the Bromacker site. However, fossil bones were rare.  It had been thought that preservation conditions had prevented body fossils from being formed.  However, the discovery of pelvic girdle bones demonstrated that this site could yield body fossils.  As part of the current research project, the bones were digitally analysed and reconstructed by researchers at the Museum für Naturkunde Berlin.

The non-destructive CT scans and digital modelling enabled the scientists to produce three-dimensional models of the material.

Project manager Professor Jörg Fröbisch (Museum für Naturkunde Berlin) commented:

“I was particularly fascinated by the first bone find right from the start. With the help of modern and CT-based 3D methods, we were able to isolate the bone, visualise it from all sides and compare it with other finds. The scales fell from our eyes, and we immediately realised that it was the pelvis of a synapsid most likely that of Dimetrodon, a distant relative of us mammals.”

Wild Safari Prehistoric World Dimetrodon model.

The picture (above) shows a Dimetrodon model. The Dimetrodon taxon associated with the Bromacker fossil site is Dimetrodon teutonis.  The model shown is from the Wild Safari Prehistoric World series of figures.

To view this range on Everything Dinosaur’s website: Wild Safari Prehistoric World Models.

Dimetrodon teutonis

Dimetrodon teutonis was probably one of the top predators in the Bromacker palaeoenvironment. It was named and described in 2001 (Berman et al). The type specimen is MNG 10598, which consists of a set of vertebrae including elements from the distinctive sail of the Dimetrodon genus. The Bromacker fossil material represents the first record of Dimetrodon outside of North America. Dimetrodon teutonis was one of the smaller species of Dimetrodon. Scientists have estimated that it measured around a metre in length and weighed approximately twenty-five kilograms.

The species epithet is from the Latin “teutonis”. This translates as an individual of a German tribe. This is a reference to the geographic origins of the fossil material.  It remains the only species of Dimetrodon known from the Bromacker fossil site.  To date, only an isolated upper jaw, skeletal parts of a dorsal sail, a shoulder girdle and limb elements have been found at the Bromacker location. The discovery of the pelvic girdle of D. teutonis will help scientists to better understand the animal’s locomotion.

Everything Dinosaur acknowledges the assistance of a media release from the Museum für Naturkunde Berlin in the compilation of this article.

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

Researchers have concluded that the remarkable fossils associated with the Yixian Formation of north-eastern China were not caused by Pompeii-like events.  The prevailing view was that these amazing fossils, some of which are preserved in stunning detail, were formed due to violent volcanic eruptions, lahars or pyroclastic flows.  However, a team of scientists writing in the journal the “Proceedings of the National Academy of Sciences”, have challenged this hypothesis.  Instead, it is suggested that the deposition took place over a period of less than 100,000 years. Furthermore, more mundane factors were at work, such as high rainfall, causing the burrows of animals to collapse.

Study co-author Paul Olsen exploring the quarry where the first feathered non-avian dinosaur was found in 1996 (Sinosauropteryx). If these fossils had formed as a result of violent volcanic events, it would have been highly unlikely that delicate structures such as feathers would have been preserved. Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory.

Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory

Far from representing Pompeii-like catastrophes, the scientists conclude that the deposits provide a brief snapshot of normal life and death in an Early Cretaceous continental community.

The Incredible Fossils of the Yixian Formation

The Lower Cretaceous deposits of the Yixian Formation exposed in Liaoning Province (north-eastern China) were virtually unexplored until the 1980s.  Villagers reported finding beautiful fossil specimens, representing all kinds of creatures that once lived in a forested environment that contained large lakes.  The rocks are believed to be around 125 million years old (Barremian faunal stage). Fossils of dinosaurs, pterosaurs, birds, mammals, amphibians, reptiles, fish and insects have been found.  Some of the most famous fossils ever found come from this part of China.

Since the first, remarkable discoveries there has been fossil gold rush with an extensive network of fossil dealers and retail outlets springing up. Both locals and scientific field teams have excavated the area so much, the dig sites can be seen from space.  These are perhaps the most extensive palaeontological excavations on Earth.

The corpse of a feathered dinosaur lies on the lake shore whilst a pair of Psittacosaurus wander past and pterosaurs fly overhead.  It had been thought that the beautiful fossils of the Yixian Formation were formed as a result of volcanic activity. Picture credit: Zheng Qiuyang.

Picture credit: Zheng Qiuyang

Flattened Fossils or Three-dimensional Fossils

The fossils occur as flattened with soft tissue preservation (including feathers and melanosomes) in laminated lacustrine strata (lake sediments) or as three-dimensional almost complete, articulated skeletons in more terrestrial orientated deposits.  The discoveries include the first documented evidence of a mammal attacking a dinosaur.

To read more about this amazing fossil discovery: Repenomamus Attacks Psittacosaurus.

Co-author of the study, Paul Olsen a palaeontologist at the Columbia University’s Lamont-Doherty Earth Observatory, commented:

“These are probably the most important dinosaur discoveries of the last 120 years. But what was said about their method of preservation highlights an important human bias. That is, to ascribe extraordinary causes, i.e. miracles, to ordinary events when we don’t understand their origins. These [fossils] are just a snapshot of everyday deaths in normal conditions over a relatively brief time.”

Analysing Grains of Zircon

Lead author of the research, Scott MacLennan (University of Witwatersrand) analysed tiny grains of the mineral zircon taken from the fossil matrix and the actual fossils. With these samples, he measured the ratios of radioactive uranium as it decays into lead. This rate of radioactive decay is constant. As a result, he was able to date the material with a high degree of accuracy. These fossils were formed around 125.8 million years ago, centred around a period of less than 93,000 years.

Further calculations showed that this timeframe contained three periods controlled by variations in the Earth’s orbit when the weather was relatively wet. This caused sediments to build up in lakes and on land much more quickly than previously had been thought. Many already deceased animals were quickly buried, and oxygen that normally would fuel decomposition was sealed out. The sealing effect was fastest in lakes, resulting in the preservation of soft tissues.

This explains why two types of fossils occur.

A field team from the Nanjing Institute of Geology and Palaeontology exploring Yixian Formation exposures (Lujiatun Member). Many Psittacosaurus fossils have been found at this locality. On the right of the photograph is one of the quarries dug by local people in search of fossils to sell. Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory.

Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory

Fossil Preservation Not Connected to Volcanism

The scientists have discounted volcanism. Previous studies have suggested that some animals were entombed in lahars. These are fast-moving concrete-like slurries of mud that flow from volcanoes following eruptions. However, lahars are extremely violent, preserving animal skeletons intact, with soft tissues preserved would be most unlikely.

In addition, other researchers have suggested that the preservation occurred due to pyroclastic flows. Pyroclastic flows involve rapidly moving waves of hot ash and poisonous gases, the sort of event that led to the remarkable preservation found in Pompeii.

There are layers of volcanic ash and lava within the layers of rock that form the Yixian Formation.  However, the fossil remains include delicate structures such as feathers and stomach contents, which could not have survived such traumatic incidents.  The scientists conclude that the evidence indicates sudden burrow collapses.  For example, the famous Repenomamus attacking the Psittacosaurus, a battle preserved in time, could have occurred when the mammal invaded the dinosaur’s burrow, and the burrow subsequently collapsed.

Rather than representing multiple, Pompeii-like terrible events, the Yixian Formation is instead a brief snapshot of normal life and death in an Early Cretaceous ecosystem.

An Economy Centred Around the Yixian Formation

Whatever, the reason for the fossil preservation, Liaoning Province is now one of the most famous parts of China.  These remarkable fossils attract tourists, and an entire industry has sprung up with extensive trading in fossil souvenirs.

Potential buyers examine fossils at a shop in the city of Chaoyang (Liaoning Province), a centre of the Chinese fossil trade. Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory.

Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory

Everything Dinosaur acknowledges the assistance of a media release from The Earth Institute/Columbia Climate School (Columbia University) in the compilation of this article.

The scientific paper: “Extremely rapid, yet noncatastrophic, preservation of the flattened-feathered and 3D dinosaurs of the Early Cretaceous of China” by Scott A. MacLennan, Jingeng Sha, Paul E. Olsen, Sean T. Kinney, Clara Chang, Yanan Fang, Jun Liu, Bennett B. Slibeck, Elaine Chen and Blair Schoene published in the PNAS.

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

Scientists have named a new species of oviraptorosaur from Inner Mongolia (China).  This new theropod has been named Yuanyanglong bainian.  The species name recognises that it is a hundred years since the naming of the first oviraptorosaur taxon.  In 1924, Oviraptor philoceratops was named and formally described.  Yuanyanglong is known from two fossil specimens recovered from the Lower Cretaceous Miaogou Formation.  The fossils come from the Maortu locality in Chilantai, Inner Mongolia.  Phylogenetic analysis suggests that it is a sister taxon to the clade formed by the Caenagathoidea and the Avimimidae.  It was a small dinosaur standing less than a metre high.

A scale drawing of the recently described oviraptorosaur from Inner Mongolia Yuanyanglong bainian. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Yuanyanglong bainian

The research team, writing in the academic journal Cretaceous Research identified several unique autapomorphies in the fossilised bones.  For example, the hindlimbs are proportionately elongated and they have fused lower segments.  In addition, the ilium (part of the pelvic girdle) has a much reduced postacetabular process.  This combination of anatomical traits is not known in other oviraptorosaurs, however, they are found in extant wading birds.  Yuanyanglong may have lived close to bodies of water.

One of the specimens PV02476-2 consists of a partial and poorly preserved skull.  However, the potential diet of this theropod can only be inferred at this time.  Preserved gastroliths similar to those associated with another oviraptorosaur – Caudipteryx have been recovered.  The research team have stated that preliminary observations indicate potential discrepancies in the digestion mode of early and late-diverging oviraptorosaurs.

The first part of the genus name is derived from “Yuanyang” the mandarin term for lovebirds (Aix galericulata). These birds form long bonds with their partners, a reference to the pair of skeletons found together.  The second part of the genus name “long” is a transliteration of the Chinese word for dragon.  The species or trivial name “bainian” translates as “one hundred years”, reflecting a hundred years since the naming of the first oviraptorosaur taxon Oviraptor philoceratops.

A scale drawing of a typical oviraptorosaur (O. philoceratops).  The species name of Yuanyanglong bainian commemorates the centenary of the naming of the first oviraptorosaur. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Rare Dinosaur Fossils

The Maortu locality in Chilantai, western Inner Mongolia has produced other vertebrate fossil remains.  However, dinosaur fossils are rare.  Some, as yet, undescribed sauropod remains have been reported.  In addition, three dinosaur taxa are known from this area.  A theropod has been described (Shaochilong maortuensis), along with a hadrosaurid Probactrosaurus gobiensis. In addition, fossils of an armoured dinosaur have been found. Gobisaurus domoculus was named and formally described in 2001 (Vickaryous et al).  Regarded as a member of the Ankylosauridae family Gobisaurus was a large, robust animal.  It may have been over six metres in length and weighed in excess of three tonnes.

A spokesperson from Everything Dinosaur commented that further analysis of vertebrate fossil remains from the Maortu locality would likely result in the announcing of new dinosaur taxa.

To read an article from 2016 about the discovery of a oviraptorosaur from southern China (Tongtianlong limosus) that provided new insights into oviraptorosaur radiation: A Fresh Perspective on Oviraptorosaur Radiation.

The scientific paper “A new oviraptorosaur from the Lower Cretaceous Miaogou Formation of western Inner Mongolia, China” by Mingze Hao, Zhiyu Li, Zhili Wang, Shuqiong Wang, Feimin Ma, Qinggele, J. Logan King, Rui Pei, Qi Zhao and Xing Xu published in the journal Cretaceous Research.

Visit the award-winning Everything Dinosaur website: Dinosaur Toys and Figures.

A recently published scientific paper suggests that rapid global cooling as a result of the release of billions of sulphate particles into the atmosphere played a significant role in the End-Triassic extinctions.

The end of the Triassic marks one of the five great mass extinctions recorded in the Phanerozoic Eon. Arguably, of these five, the End-Triassic extinction is the least understood by Earth scientists. The mechanisms of extinction remain open to debate. However, it is known that during this time there was extensive volcanic activity.  Pangaea began to tear itself apart, the first step in a process that led to the creation of the Atlantic Ocean. The Atlantic is still widening today.

Enormous outpourings of basaltic lava occurred covering the entire (modern) eastern seaboard of the United States, reaching as far west as Texas and probably as far south as Venezuela. These basaltic extrusions have counterparts in Europe and northern Africa that are approximately the same age. These huge eruptions are known collectively as the Central Atlantic Magmatic Province (CAMP).

A New Theory to Explain the End-Triassic Extinctions

It had been thought that huge concentrations of carbon dioxide pumped into the atmosphere led to global warming and the acidification of the world’s marine environments.  Intriguingly, a new study suggests it was sudden and dramatic global cooling that led to the extinction of many animals.

This new study suggests that the first eruptions were immense but relative brief events, lasting less than a hundred years each. Sunlight-reflecting sulphate particles were ejected into the atmosphere, rapidly cooling the planet. The extreme cold changed the biota of planet Earth. The Earth’s temperature began to rise with the increase of carbon dioxide in the atmosphere and global warming took place. However, the researchers conclude that it was the rapid freezing that resulted in the collapse of ecosystems and the initial mass extinctions.

The photograph shows red sandstone deposits in Morocco associated with the Triassic to Jurassic boundary. Red sediments in many locations around the world contain fossils of Triassic fauna and flora. The white caps are sediments laid down by extensive volcanism, as is evidenced by the grey/black basalt layers topping the assemblage. Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory.

Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory

Lead author of the paper, Dennis Kent, Adjunct Senior Research Scientist at Lamont-Doherty Earth Observatory at Columbia University, stated:

“It takes a long time for carbon dioxide to build up and heat things, but the effect of sulphates is pretty much instant. It brings us into the realm of what humans can grasp. These events happened in the span of a lifetime.”

To read another article about Triassic extinction theories: The Carnian Pluvial Episode and Extinction.

Correlating Data from CAMP Deposits

The researchers gathered data from CAMP deposits in the mountains of Morocco, in the Bay of Fundy (Nova Scotia) and from the Newark Basin (New Jersey). The focused their study on the alignment of magnetic particles within the strata. The orientation of these particles records the historical drift of the Earth’s magnetic pole during the time of the volcanic activity.

The magnetic pole is not fixed, it shifts from the planet’s stable axis of rotation—true north—and changes position by a few tenths of a degree each year. This is why compasses do not point at true north. As a result, magnetic particles in lava flows that occurred within a few decades of each other will align in the same direction, whereas those from thousands of years later could be misaligned by twenty to thirty degrees.

Red Triassic sandstones capped by volcanic ash in the Bay of Fundy (Nova Scotia). Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory.

Picture credit: Paul Olsen/Lamont-Doherty Earth Observatory

Five successive pulses of the Central Atlantic Magmatic Province (CAMP) lava were identified. These pulses covered a time span of approximately 40,000 years. Each lava pulse exhibited magnetic particle alignment in a single direction, suggesting that these eruptions happened within a window of around a hundred years. This is far too short a period of time for significant magnetic pole drift to occur.

The research team concluded that these eruptions released huge amounts of sulphates into the atmosphere. These particles blocked sunlight and led to global temperatures plummeting. Carbon dioxide can remain in the atmosphere for centuries. However, volcanic sulphate aerosols are dissipated within a few years. Consequently, while these volcanic winters were extreme, their duration was relatively short.

The researchers likened the CAMP episodes to the sulphate emissions from the 1783 eruption of Iceland’s Laki volcano, which triggered one of the coldest years on record and caused widespread crop failures. However, it is emphasised that the CAMP eruptions were hundreds of times more powerful.

Everything Dinosaur acknowledges the assistance of a media release from The Earth Institute/Columbia Climate School (Columbia University) in the compilation of this article.

The scientific paper: “Correlation of sub-centennial-scale pulses of initial Central Atlantic Magmatic Province lavas and the end-Triassic extinctions” by Dennis V. Kent, Paul E. Olsen, Huapei Wang and Mohammed Et-Touhami published in the Proceedings of the National Academy of Sciences.

Researchers have named and described one of the oldest dinosauromorphs known to date.  This new archosaur has been named Gondwanax paraisensis and it has been classified as a silesaurid. Controversies remain over the phylogenetic position of the Silesauridae.  They are members of the Archosauria clade but are they a sister-group to the Dinosauria or early ornithischian dinosaurs?  Silesaurid fossils are crucial for comprehending the origins and early evolution of the dinosaurs. The fossils of Gondwanax reveal a suite of characteristics that can help palaeontologists to better understand the rise of the Dinosauria.

A life reconstruction of Gondwanax paraisensis. Picture credit: Matheus Fernandes Gadelha.

Picture credit: Matheus Fernandes Gadelha

Gondwanax paraisensis

The fossilised remains were excavated from the Dinodontosaurus Assemblage Zone of the Santa Maria Formation (Ladinian-Carnian boundary).  The fossils are thought to be around 237 million years old. Basal silesaurids have two sacral vertebrae. However, Gondwanax had three. This is the oldest occurrence of this characteristic in the fossil record. Having at least three sacral vertebrae is a defining anatomical trait of dinosaurs.

A close view of one of the vertebrae of G. paraisensis. Picture credit: Rodrigo Temp Müller.

Picture credit: Rodrigo Temp Müller

The Santa Maria Formation is found in the Rio Grande do Sul region of southern Brazil. The strata represent sediments laid down in the Middle and Upper Triassic. It preserves a remarkable vertebrate fauna including cynodonts, early dinosaurs, dinosauromorphs and rauisuchians.  The Dinodontosaurus Assemblage Zone is named after the dicynodont Dinodontosaurus, which is particularly abundant.

To read more about fossil discoveries from the Dinodontosaurus Assemblage Zone: One of the Oldest Dinosauromorphs.

A view of the fossil site location. The strata here is part of the Dinodontosaurus Assemblage Zone (AZ) of the Santa Maria Formation. Picture credit: Rodrigo Temp Müller.

Picture credit: Rodrigo Temp Müller

An Agile and Lightweight Animal

The researchers estimate that Gondwanax was a fast-running, agile animal. It measured around a metre in length and would have weighed between three and six kilograms.  The absence of any skull material has prevented the scientists from commenting on its diet, but it was much smaller than many of its contemporaries.  For example, the apex predator in the ecosystem was probably Prestosuchus chiniquensis. Now tentatively assigned to the Rauisuchia, P. chiniquensis measured nearly seven metres long. Gondwanax probably used its speed and agility to avoid the jaws of Prestosuchus.

The Wild Safari Prehistoric World Prestosuchus model.

The picture (above) shows a model of the fearsome Triassic predator Prestosuchus.  This figure is one of the prehistoric animals featured in the Wild Safari Prehistoric World range.

To view this range of models: Wild Safari Prehistoric World Models.

A life reconstruction of Gondwanax paraisensis (see human silhouette for scale). In addition, a skeleton reconstruction shown in lateral view (scale bar equals 50 cm) and a world map showing the approximate location of the fossil discovery. Picture credit: Matheus Fernandes Gadelha.

Picture credit: Matheus Fernandes Gadelha

Evidence of a Fourth Trochanter

The researchers are uncertain as to whether the disarticulated bones represent one animal or several individuals. The femur did reveal the presence of a fourth trochanter.  This is a knob-like protrusion located on the shaft of the femur that acted as an anchor point for muscles that helped to pull the hind leg backwards.  It is thought that the evolution of this feature on the thigh bone permitted members of the Dinosauria to develop a bipedal gait.

The author of the scientific paper, Dr Rodrigo Temp Müller commented that these anatomical features probably permitted Gondwanax to move around much more efficiently than other reptiles within the ecosystem.  The evolution of an efficient, upright gait might be one of the reasons for the eventual success and domination of the Dinosauria.

The femur of Gondwanax paraisensis. The thigh bone preserves some signs of a 4th trochanter, which is a common characteristic shared by archosaurs. It is a knob-like process that indicates muscle attachment. The researcher suggests that the presence of this anatomical feature suggests that this silesaurid had “advanced locomotor capability”. Picture credit: Rodrigo Temp Müller.

Picture credit: Rodrigo Temp Müller

Fossil enthusiast Pedro Aurelio stumbled upon remains causing excitement in the scientific community at Paraiso do Sul, a location known for unearthing precursors to mammals and even a miniature crocodile species called Parvosuchus aurelioi. These fossil finds swiftly moved to the research hub at the Universidade Federal de Santa Maria’s Palaeontology Research Centre, where Dr Muller embarked on the delicate process of preparing and examining this piece of prehistoric life and carefully removing the surrounding rock matrix.

Niche Differentiation

Writing in the academic journal “Gondwana Research”, Dr Temp Müller comments that the co-occurrence of Gondwanax paraisensis and a second silesaurid (Gamatavus antiquus) in the same Assemblage Zone represents the oldest evidence of sympatry among “silesaurids” in South America. Two related species living at the same time in the same habitat.  In addition, the unique combination of sacral and hindlimb anatomical traits suggests distinct behaviours for these two species.  This could be an example of niche differentiation within the same ecosystem.

Author of the scientific paper Rodrigo Temp Müller examining fossils of Gondwanax. Picture credit: Janaína Brand Dillmann.

Picture credit: Janaína Brand Dillmann

Everything Dinosaur acknowledges the assistance of the author of the scientific paper in the compilation of this article.

The scientific paper: “A new “silesaurid” from the oldest dinosauromorph-bearing beds of South America provides insights into the early evolution of bird-line archosaurs” by Rodrigo Temp Müller published in Gondwana Research.

The award-winning Everything Dinosaur website: Prehistoric Animal Models.

Scientists have described the smallest non-avian dinosaur eggs known to date.  The eggs, the smallest of which measures just 2.9 centimetres in length were probably laid by a small theropod.  The researchers have erected a new ootaxon Minioolithus ganzhouensis. This discovery increases the diversity of dinosaur eggs in the Late Cretaceous and is significant for our understanding of the evolution of theropods.  Everything Dinosaur contacted one of the authors of the scientific paper and we were emailed an image showing this remarkable dinosaur fossil.

Minioolithus ganzhouensis the smallest non-avian dinosaur eggs discovered to date. The fossil which represents a clutch of six, tiny theropod eggs was discovered at a construction site in Ganzhou (south-eastern China). Picture credit: Shukang Zhang (IVPP).

Picture credit: Shukang Zhang (IVPP)

Minioolithus ganzhouensis

The Upper Cretaceous Ganzhou Basin exposures located in Jiangxi Province have yielded exquisite fossils of dinosaur nests, eggs and embryos. Most of these egg fossils represent oviraptorosaurs. However, troodontid, hadrosaur and potential dromaeosaurid egg fossils have also been reported. Scientists have been able to learn about dinosaur nesting and reproductive behaviours. Intriguingly, all the eggs known from these deposits were relatively large. Writing in the academic journal “Historical Biology”, the researchers describe a partial clutch with six complete small eggs. The fossil material comes from the Tangbian Formation and the eggs are thought to be around eighty million years old.

China has provided a wealth of dinosaur egg fossils.  Furthermore, the theropod egg fossils have helped to shed light on the relationship between avian and non-avian dinosaurs.  For example, a remarkable dinosaur egg fossil from southern China demonstrated the “tucking” position in an embryo. This posture is seen in the embryos of modern birds. It is a behaviour controlled by the central nervous system and it is critical for hatching success.

To read more about the remarkable theropod embryo fossil: Exquisitely Preserved Theropod Embryo Found Inside Egg.

Mike from Everything Dinosaur commented:

“This is a remarkable fossil find.  Our thanks to the research team for sharing the image with us.  Discoveries such as this are helping palaeontologists to learn more about the remarkable links between today’s birds and their theropod ancestors.”

Everything Dinosaur acknowledges the assistance of one of the scientific paper’s authors in the compilation of this article.

The scientific paper: “The smallest known complete dinosaur fossil eggs from the Upper Cretaceous of South China” by Rui Wu, Fasheng Lou, Juan Yu, Yu Xue, Shukang Zhang, Ling Yang, Wenjiang Qiu, Huimin Wang and Fenglu Han published in Historical Biology.

The award-winning Everything Dinosaur website: Dinosaur and Prehistoric Animal Models.

Remarkable Arthropleura fossils from France offer new insights into the life and behaviour of one of the largest invertebrates known to science.  For the first time, scientists have revealed the head of this giant arthropod in detail.  Intriguingly, this study suggests that this Carboniferous creature had characteristics of both millipedes and centipedes.  Arthropleura was a giant arthropod.  For years, palaeontologists had only fragmentary body fossils to study.  It was thought that it was a giant millipede, probably herbivorous, but the absence of any fossil material representing the head had meant that scientists could not be certain about its taxonomy.

The CT analysis of a fossil preserving the head surprised the research team.  The head displays traits similar to early centipedes. This suggests that millipedes and centipedes may be more closely related than previously thought.

Arthropleura sp., specimen MNHN.F.SOT002123, details on the ventral sclerites and the feeding apparatus revealed by computer modelling after a CT scan of the fossil. Picture credit: Lhéritier et al.

Picture credit: Lhéritier et al

A Giant Invertebrate

Regarded as one of the largest land invertebrates of all time, some specimens may have measured over 2.6 metres in length. Arthropleura belongs to the arthropod group, which includes insects, crustaceans, and arachnids.  It had been thought that it preferred damp, swampy environments.  However, a study of fossil material published in 2021 indicated that larger individuals may have inhabited open woodland.

To read more about the giant invertebrate Arthropleura: Largest-ever Arthropleura Fossils Described.

An out-dated reconstruction of the giant arthropod Arthropleura.

The researchers, writing in the academic journal Science Advances, reveal breath-taking details identified from CT scans.  The fossils do not represent fully grown individuals.  However, they reveal important new details.  Notably, the head morphology is similar to that of early centipedes.

One of the authors of the paper, Dr Greg Edgecombe from the London Natural History Museum explained how these fossils helped refine our understanding of Arthropleura. He explained that previously, the presence of two pairs of legs on each body segment indicated affinity with millipedes.  Therefore, Arthropleura was thought to be a giant millipede.  However, now that fossil material representing the head has been studied, this theory has been challenged.  The head had enclosed mandibles and two pairs of head limbs behind them.  These fossils challenge long held views on millipede and centipede taxonomy.

By combining data from hundreds of genes in living species with physical characteristics of fossils like Arthropleura, the situation was clarified. Millipedes and centipedes are actually each other’s closest relatives.

Studying Arthropleura Fossils

Many aspects of Arthropleura’s life remain a mystery, such as how it breathed and what it ate. Researchers are gradually forming a clearer picture of this invertebrate.

Living between 346 and 290 million years ago, Arthropleura was the largest land invertebrate during an era of giant arthropods. When these animals died, sediment quickly buried them. Some became encased in a mineral called siderite, forming nodules. These fossils preserved even the most delicate anatomical features, making them valuable for researchers.

After hundreds of millions of years of continental drift, some siderite nodules surfaced in a coal mine in Montceau-les-Mines, France, during the 1970s. They later went to the Museum of Autun, where CT scans are finally revealing their hidden contents.

In the past, these nodules would have been split open and casts taken to produce three-dimensional replicas of the fossils.  However, the paper outlines how the Arthropleura fossils were scanned using a combination of microCT and synchrotron imagery to examine the Arthropleura inside, revealing the fine details of its anatomy.

A photograph of a latex cast taken from an Arthropleura fossil, the counterpart to specimen number MNHN.F.SOT002122. Picture credit: Lhéritier et al.

Picture credit: Lhéritier et al

Two Important Specimens

Two specimens were of particular significance to the researchers. These fossils represent juveniles. They measure just twenty-five and forty millimetres long, it is these fossils that reveal how Arthropleura reached a huge size.

Arthropleura specimens have different amounts of body segments. This suggests that these invertebrates added them until they reached a fixed maximum number. This is like most extant millipedes but differs from many centipedes, which are born with all of their segments already in place.

This means that Arthropleura’s maximum size would have been reached by, or after, sexual maturity, rather than at birth. The maximum size of the species used in the study is an open question, but it may not have been as massive as some of the biggest fossil specimens of Arthropleura spp. indicate.

It had been suggested that Arthropleura inhabited swampy environments. Whilst it was probably limited to equatorial regions, a recent study suggests it preferred open woodland. Picture credit: National Museum of Wales.

Picture credit: National Museum of Wales

Eyes on Stalks

Other aspects of their lifestyle are similarly ambiguous. While the researchers found that Arthropleura had club-shaped eyes, their structure has not survived. Moreover, startlingly, the Arthropleura fossils reveal that the eyes were on stalks. This is not a common feature in centipedes and millipedes. The team believe they were probably compound eyes, based on the animal’s relatives, but they cannot be certain.

No venom fangs or legs specialised for catching prey were found. Its legs are better adapted for slow movement. It is likely that Arthropleura was a detritus-eating animal, with a diet similar to modern day millipedes.

Everything Dinosaur acknowledges the assistance of the media team at the London Natural History Museum in the compilation of this article.

The scientific paper: “Head anatomy and phylogenomics show the Carboniferous giant Arthropleura belonged to a millipede-centipede group” by Mickaël Lhéritier, Gregory D. Edgecombe, Russell J. Garwood, Adrien Buisson, Alexis Gerbe, Nicolás Mongiardino Koch, Jean Vannier, Gilles Escarguel, Jérome Adrien, Vincent Fernandez, Aude Bergeret-Medina and Vincent Perrier published in Science Advances.

The Everything Dinosaur website: Prehistoric Animal Toys.

Remarkable cynodont fossils from southern Brazil are helping researchers from the University of Bristol and their South American colleagues to better understand mammal evolution.  The fossils represent the mammal-precursors Brasilodon quadrangularis and Riograndia guaibensis.  These animals lived in the Late Triassic.  The fossils provide a critical insight into the development of the mammalian middle ear and jaw.  These key anatomical features of the Mammalia may have evolved millions of years earlier than previously thought.

Getting to Grips with Mammal Evolution

Mammals have a distinctive jaw structure and have evolved three middle ear bones to help with hearing.  The evolutionary transition from earlier tetrapods which had a single middle ear bone, has intrigued palaeontologists.  This new research, published in the journal “Nature” examines how mammalian ancestors (cynodonts), evolved these features over time.

Computed tomography (CT scans) was used to create digital models of the jaw joint of these Brazilian cynodonts.  The scientists discovered a “mammalian-style” contact between the skull and the lower jaw in Riograndia guaibensis.  This feature was not found in the Brasilodon quadrangularis fossil material.   B. quadrangularis is closer to the stem mammals than Riograndia guaibensis. This discovery suggests that the defining mammalian jaw feature evolved multiple times in different groups of cynodonts.  In addition, Riograndia lived around seventeen million years earlier than the previous oldest known example of this structure.  This indicates that this anatomical feature had evolved earlier than previously thought.

Riograndia guaibensis and Brasilodon quadrangularis life reconstruction. Brasilodon quadrangularis (left) and Riograndia guaibensis (right). Picture credit: Jorge Blanco.

Picture credit: Jorge Blanco

Brazilian cynodont fossils have played an important role in helping to better understand mammal evolution. In 2022, Everything Dinosaur reported on an analysis of the teeth of Brasilodon quadrangularis that led palaeontologists to suggest the Mammaliaformes (the lineage leading to the modern Mammalia), originated some twenty million years earlier than previously perceived.

To read this article: Nibbling Away at the Earliest Date for True Mammals.

New Study Suggests Mammaliaformes Experimented with Different Jaw Functions

The authors of this new study conclude that Mammaliaformes experimented with different jaw functions, leading to the evolution of “mammalian” traits independently in various lineages.

Lead author of the study, James Rawson (University of Bristol) explained:

“The acquisition of the mammalian jaw contact was a key moment in mammal evolution. What these new Brazilian fossils have shown is that different cynodont groups were experimenting with various jaw joint types, and that some features once considered uniquely mammalian evolved numerous times in other lineages as well.”

This new research has significant implications for the understanding of the early stages of mammal evolution.  The study illustrates that features such as the mammalian jaw joint and middle ear bones evolved in a patchwork, or mosaic, fashion across different cynodont groups.

Fossils from Brazil Have Global Significance for Understanding Mammal Evolution

Co-author of the study, Dr Agustín Martinelli (Museo Argentino de Ciencias Natural, Buenos Aires) added:

“Over the last years, these tiny fossil species from Brazil have brought marvellous information that enrich our knowledge about the origin and evolution of mammalian features. We are just in the beginning and our multi-national collaborations will bring more news soon.”

The researchers are eager to investigate further the South American fossil record.  It has proven to be a rich source of new information on mammalian evolution.

Professor Marina Soares of the Museu Nacional, Brazil, exclaimed:

“Nowhere else in the world has such a diverse array of cynodont forms, closely related to the earliest mammals.”

By integrating these findings with the results from other studies, the scientists hope to deepen their understanding of how early jaw joints functioned and contributed to the development of the Mammalia.

James added:

“The study opens new doors for palaeontological research, as these fossils provide invaluable evidence of the complex and varied evolutionary experiments that ultimately gave rise to modern mammals.”

Everything Dinosaur acknowledges the assistance of a media release from the University of Bristol in the compilation of this article.

The scientific paper: “Brazilian fossils reveal homoplasy in the oldest mammalian jaw joint” by James Rawson et al published in Nature.

The Everything Dinosaur website: Dinosaur and Prehistoric Mammal Toys.

Following the publication of a scientific paper describing Coahuilasaurus lipani the Saurolophinae evolutionary tree has been updated.  Coahuilasaurus was named and described by Longrich et al. This new Mexican hadrosaur is known from the front end of a skull.  It differs from related species in having a very short, deep muzzle and a series of tooth-like projections on the roof of the mouth. The genus name is derived from the Coahuila State and the Greek “sauros” for lizard. The species name honours the Lipani Apache tribe of northern Mexico.

It had been thought that the fossil material represented a Kritosaurus. However, a more detailed analysis revealed unique traits which permitted the establishment of a new species of hadrosaur.

To read Everything Dinosaur’s blog post about Coahuilasaurus lipani: A New Duckbill Dinosaur from Northern Mexico.

The Saurolophinae Evolutionary Tree

The phylogeny of Coahuilasaurus. Evolutionary tree of the Saurolophinae, showing the relationships of Coahuilasaurus within the Kritosaurini. Picture credit: Longrich et al.

Picture credit: Longrich et al

The researchers performed two phylogenetic analyses. The information used was given different weights, and the two sets of results are different. However, the second analysis is better-resolved and is in line with the stratigraphy.

Both analyses recover three major subclades within the Kritosaurini tribe.

1. Coahuilasaurus lipani, Gryposaurus utahensis, Rhinorex condrupus, and Gryposaurus notabilis.
2. Naashoibitosaurus ostromi, Anasazisaurus horneri, and Kritosaurus navajovius.
3. Comprises the South American kritosaurins, the Austrokritosauria, as well as “Gryposaurus” alsatei.

The Wild Safari Prehistoric World Gryposaurus dinosaur model.

The image (above) shows the Gryposaurus model that was introduced by Safari Ltd in 2013. This figure has been retired.

To view the range of Wild Safari Prehistoric World figures in stock at Everything Dinosaur: Wild Safari Prehistoric World Figures.

The scientific paper: “Coahuilasaurus lipani, a New Kritosaurin Hadrosaurid from the Upper Campanian Cerro Del Pueblo Formation, Northern Mexico” by Nicholas R. Longrich, Angel Alejandro Ramirez Velasco, Jim Kirkland, Andrés Eduardo Bermúdez Torres and Claudia Inés Serrano-Brañas published in the journal MDPI Diversity.

Visit the award-winning Everything Dinosaur website: Dinosaur Models.

A team of international scientists have described a new species of hadrosaur from the end of the Cretaceous. The dinosaur, from Coahuila in northern Mexico has been named Coahuilasaurus lipani. The cranial material used to describe this new duckbill dinosaur was previously identified as Kritosaurus. A closer examination revealed unique autapomorphies of the snout and beak that led to the establishment of this new taxon. Along with other recent dinosaur discoveries from Mexico, Coahuilasaurus shows that Mexico had different species of dinosaurs than the United States and Canada.

Coahuilasaurus lipani life reconstruction. Picture credit: C. Díaz Frías.

Picture credit: C. Díaz Frías

Coahuilasaurus lipani

The new duckbill is known from the front end of a skull. Coahuilasaurus differs from related species in having a very short, deep muzzle and a series of tooth-like projections on the roof of the mouth. The unusual morphology of the jaws suggests a specialisation for the consumption of tough vegetation like palms and cycads.

In recent years, scientists have found a rich fauna of dinosaurs in northern Mexico, like the horned dinosaur (Coahuilaceratops), the crested duckbills Velafrons and Tlatolophus, and now a new kritosaurin hadrosaurid Coahuilasaurus.  Mexico in the Late Cretaceous was very different from today.  It was not an arid, desert environment.  Instead, it was a tropical rainforest full of palm trees and bananas, bordering the Gulf of Mexico.

The Cerro del Pueblo Formation, in Coahuila State, Mexico. Picture credit: Longrich et al.

Picture credit: Longrich et al

An article from 2008 providing information on the discovery of Velafrons coahuilensis: Duckbilled Dinosaur from “South of the Border”.

A blog post from 2010 about the ceratopsian Coahuilaceratops magnacuerna: A New Genus of Horned Dinosaur.

To read a blog post from 2021 about the discovery of Tlatolophus galorum: A New Lambeosaurine from the Gulf of Mexico.

The Different Dinosaur Biotas of Laramidia

Further north, in the USA and Canada, completely different dinosaurs existed. For example, the duckbill Edmontosaurus and the ceratopsian Pachyrhinosaurus. The identification of a new taxon fits the pattern where dinosaurs in the south are distinct from the ones in the northern parts of the ancient landmass of Laramidia.

The dinosaur biota of the Cerro del Pueblo Formation. Picture credit: Longrich et al.

Picture credit: Longrich et al

There are lineages of dinosaurs that disappear from the north but persist for longer in the south. The southern dinosaurs seem to be very different from the northern dinosaurs, so it may be that a lot of what we think we know – including what dinosaur diversity was doing at the very end of the Cretaceous is biased by the fact that until now palaeontologists have been more focused on the dinosaur biota from northern Laramidia.

A drawing of the skull of Coahuilasaurus lipani with known bones show in white (A). A silhouette of C. lipani (B), note the scale bar in (A) of 20 cm and (B) one metre. Picture credit: Longrich et al.

Picture credit: Longrich et al

Commenting on the significance of this new dinosaur discovery Dr Nick Longrich (University of Bath), and a co-author of the study stated:

“Dinosaurs apparently had very small geographic ranges compared to modern mammals, which often range across entire continents. Which is bizarre given that big animals tend to have huge ranges. But what this means is that even in a relatively small area like western North America, you could pack huge numbers of species into a small landmass. Since we’ve only explored a few places for dinosaurs, that implies there’s a huge diversity of dinosaurs waiting to be discovered.”

More Dinosaur Discoveries from Mexico are Likely

Some of those dinosaurs may never be found.  For example, some may never have been preserved as fossils. The remains of others are buried far beneath the ground, or their fossils eroded out millions of years ago and have been weathered away. However, in Coahuila there are vast regions of desert that have hardly been explored.  It is likely that more dinosaur fossils representing new taxa will be discovered in northern Mexico.

The holotype of Coahuilasaurus lipani. The unique morphology of the skull and jaws led to the establishment of a new species of kritosaurin hadrosaurid. Picture credit: Longrich et al.

Picture credit: Longrich et al

Dr Longrich added:

“Canada and the United States have been pretty well-explored at this point. We’ll keep finding new dinosaurs there, but it’s slow going, the low-hanging fruit, the common species we’ve found. Mexico is terra incognita. There’s a lot of dinosaurs waiting to be discovered, we just need to get out there and find them.”

Everything Dinosaur acknowledges the assistance of the Department of Life Sciences (Bath University) and Dr Nicholas Longrich for the compilation of this article.

The scientific paper: “Coahuilasaurus lipani, a New Kritosaurin Hadrosaurid from the Upper Campanian Cerro Del Pueblo Formation, Northern Mexico” by Nicholas R. Longrich, Angel Alejandro Ramirez Velasco, Jim Kirkland, Andrés Eduardo Bermúdez Torres and Claudia Inés Serrano-Brañas published in the journal MDPI Diversity.

The Everything Dinosaur website: Prehistoric Animal Models and Toys.