Researchers from the Smithsonian Institute (Washington), the University of Oslo and the Ludwig Maximilian Universität (Munich), have published a paper that describes two ichthyosaur specimens from the famous Upper Jurassic Solnhofen deposits of southern Germany. The fossils, an almost complete Aegirosaurus (JME-SOS-08369) and a tail (JME-SOS183), reveal extensive soft tissue preservation, analysis of which indicates the presence of blubber in these marine reptiles.

Late Jurassic Aegirosaurus sp. (JME-SOS-08369) shown in (A) in normal light and (B) composite picture in UV light indicating location of further close-up images included in the scientific paper. Interpretative drawing (C). Note scale bar equals 20 cm. Picture credit: Delsett et al.

Picture credit: Delsett et al

These amazing fossil specimens representing marine reptiles that lived around 150 million years ago will help scientists to better understand how soft tissue can be preserved in the carcases of vertebrates deposited on the seafloor.

For models and replicas of ichthyosaurs and other prehistoric animals: Ichthyosaurs and Prehistoric Animal Models (CollectA).

Aegirosaurus

Aegirosaurus is a genus of ichthyosaur within the Ophthalmosauridae family. Its fossils are associated with the Upper Jurassic limestone deposits of Solnhofen in southern Germany. These deposits are famous for their vertebrate fossils, although ichthyosaur material is rare. Fossils ascribed to this genus have also been found in Lower Cretaceous strata in south-eastern France (Fischer et al, 2011). This discovery suggests that most Late Jurassic ichthyosaurs came through the end Jurassic extinction and continued to thrive in the Early Cretaceous.

Aegirosaurus was an active, nektonic pursuit predator, probably feeding on small fish and squid.

Picture credit: DPA

Evidence for Blubber

The nearly complete ichthyosaur skeleton (JME-SOS-08369) was excavated in 2009, whereas the second specimen involved in this study (the tail), was originally found in 1926, but not formally described. No genus has been assigned to the tail specimen, although the researchers confidently assign it to the Ophthalmosauridae.

The Late Jurassic ichthyosaur tail (specimen number JME-SOS2183) shown in (A) regular light, under ultraviolet light (B) with an interpretative line drawing (C). Note scale bar equals 10 cm. Picture credit: Delsett et al.

Picture credit: Delsett et al

Soft tissue samples were analysed using X-ray diffraction (XRD) and scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDS) analysis. The analyses confirm the presence of the phosphate mineral apatite, with phosphate most likely derived from the body itself. In addition, a yellow-coloured, amorphous substance was identified, the researchers postulate that this substance represents decomposed blubber.

Skull from Late Jurassic Aegirosaurus sp. (JME-SOS-08369) with (A) interpretative drawing and (B) photograph. Note scale bar equals 5 cm. Picture credit: Delsett et al.

Picture credit: Delsett et al

Identifying Adipocere

The researchers conclude that the detailed analysis of the yellowish, amorphous substance indicates that it is adipocere. This is late-stage post-mortem decomposing fatty acids produced by microorganisms under low oxygen conditions. As adipocere is a typical breakdown product of animal blubber, it is postulated that these ichthyosaurs had blubber to help insulate them, just as many extant marine mammals do. The paper does not address any endothermic implications for this conclusion.

Understanding Ichthyosaur Taphonomy

The two ichthyosaur specimens with their extensive soft tissue preservation will help scientists to interpret the taphonomy (how fossils are preserved) of Solnhofen Archipelago vertebrates. Future research will focus on microscopical and geochemical analysis of different parts of the specimens that have the potential to reveal more information about tissue types.

In addition, the beautifully preserved fossils hold the potential for investigations into the locomotion of ophthalmosaurids, helping scientists to better understand how these marine reptiles moved through the water.

The scientific paper: “The soft tissue and skeletal anatomy of two Late Jurassic ichthyosaur specimens from the Solnhofen archipelago” by Lene L. Delsett​, Henrik Friis, Martina Kölbl-Ebert and Jørn H. Hurum published in PeerJ.

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Scientists have identified a trackway made by a large theropod dinosaur as it crossed shallow water, the tracks are exceptionally wide and reveal that this unfortunate predator probably had a dislocated toe.

Writing in the open access journal PLOS One, the researchers describe an exceptionally wide trackway (LH-Mg-10-16), made by a meat-eating dinosaur at a site at the Las Hoyas locality (La Huérguina Formation), in central Spain. The trackway consists of six prints (three left and three right prints) and has been interpreted as representing a large theropod dinosaur crossing shallow water, blanketed by a microbial mat.

Views of the LH-Mg-10-16 theropod trackway. Cartography done in the field (A), (B) scanned surface of the trackway, mounted from a set of colour photos. Colour ramp, showing the depths and the countours of the site (in cm). Note scale bar equals 1 metre. The cartography is reprinted from Las Hoyas a Cretaceous wetland, Gibert JM et al. under a Creative Commons BY licence, with permission from Dr. Friedrich Pfeil Verlag, original copyright 2016. Picture credit: Herrera-Castillo et al.

Lower Cretaceous (Barremian Faunal Stage)

The famous Las Hoyas site has been dated to around 129-127 million years ago (Barremian faunal stage of the Early Cretaceous). Although the Las Hoyas locality has yielded many amazing vertebrate fossils (birds, amphibians, fish), dinosaur fossils are relatively rare. Stride length calculations indicate that the theropod that produced this trackway had a hip height of around two metres. This would suggest a total body length of approximately eight metres. As far as Everything Dinosaur team members are aware, the only large theropod described from fossils associated with Las Hoyas is Concavenator (C. corcovatus).

It is not possible to determine the genus from these tracks, although the prints indicate a theropod that was either bigger than Concavenator or an exceptionally large Concavenator specimen. The known foot bones of Concavenator would have created a print, approximately half the size of the LH-Mg-10-16 tracks. This suggests that there may have been a much larger, as yet undescribed, theropod present in the Las Hoyas ecosystem.

The new for 2020 Wild Safari Prehistoric World Concavenator dinosaur model.

The picture (above) shows a Wild Safari Prehistoric World dinosaur model.

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

Theropod Dinosaur Crossing Water

Sedimentary analysis indicate that the trackway was produced as the dinosaur traversed a microbial mat located on the bed of a watercourse. Marks on the surface of the substrate have been diagnosed as swimming traces of fish. The ichnospecies Undichna unisulca has been proposed, an ichnotaxon associated with the Las Hoyas site. The research team postulate that the trails were made by a type of deep-bodied bony fish (pycnodontiform), although body fossils of these fish are not common at Las Hoyas.

Undichna fish trails in Magenta LH-Mg-10-16. Fish trails (A and B) associated to the theropod footprints with interpretative line drawings (C) and (D). Lines in black trails and in red, wrinkles marks. Scale equals 10 cm. Picture credit: Herrera-Castillo et al.

A Damaged Left Foot

Detailed analysis of the trackway suggests that the “wide-steps” of the theropod are not unusual compared to other bipedal dinosaur tracks, but they do confirm that these trace fossils were made by a single individual animal.

The right footprints are more regular in shape compared to those made by the left foot. On the left foot the limited impressions made by digit II suggest that either this toe is missing or it is dislocated in some way. Birds suffer from “crooked toes”, a condition caused due to environmental factors, dietary deficits or genetics. In theropod dinosaurs it is often digit II that shows pathology including damage to the bones.

Taphonomic features of the theropod prints. Left footprints (A) and right footprints (B). The right footprints are more regular in shape whilst analysis of the left footprints suggest that this dinosaur had an injured foot. The scientists suggest that digit II of the left foot was either missing or dislocated. Picture credit: Herrera-Castillo et al.

Evidence of a Deformity or Injury

The research team concludes that despite a suspected toe injury/deformity the tracks reveal no signs of a limp. These remarkable trace fossils have captured a moment in time during the Early Cretaceous when a large, meat-eating dinosaur with a body length in excess of eight metres crossed a pool of water that was teaming with fish.

The scientific paper: “A theropod trackway providing evidence of a pathological foot from the exceptional locality of Las Hoyas (upper Barremian, Serranía de Cuenca, Spain)” by Carlos M. Herrera-Castillo, José J. Moratalla, Zain Belaústegui, Jesús Marugán-Lobón, Hugo Martín-Abad, Sergio M. Nebreda, Ana I. López-Archilla and Angela D. Buscalioni published in PLOS One.

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

The debate continues as to when the first dinosaurs evolved. Some of the oldest specimens described to date come from the famous Ischigualasto Formation located in north-western Argentina. These sediments are estimated to be around 232 million years old. It is thought that the first true dinosaurs evolved in the Southern Hemisphere and many palaeontologists favour a South American origin whilst others consider the evolutionary cradle of the Dinosauria was Africa: Dinosaurs Out of Africa?

To compound this debate, the fossil record of the ancestors of dinosaurs is particularly sparse. Some older Argentinian deposits have provided evidence of the precursors to the “true dinosaurs”, with some of these fossils estimated to be around 236 million years of age. However, scientists from the Universidade Federal de Santa Maria (Rio Grande do Sul, Brazil), have reported the discovery of a single fossilised thigh bone from Middle Triassic sediments in Brazil that predates all the Argentinian dinosauromorph fossils.

A skeletal drawing showing the placement of the right femur bone (shown in white) and a photograph of the actual fossil. Skeletal drawing by Maurício Silva Garcia, photography by Rodrigo Temp Müller. Note scale bar = 50 cm.

Picture credit: Maurício Silva Garcia/Rodrigo Temp Müller

The Dinodontosaurus Assemblage Zone

The fossilised thigh bone (right femur) measures 11 cm in length and it comes from Middle Triassic sediments (Pinheiros-Chiniquá Sequence) from the famous Dinodontosaurus Assemblage Zone, so named because as well as archosaur fossils, the sediments have yielded an abundance of fossil material associated with the dicynodont Dinodontosaurus. The femur has a morphology similar to the thigh bones of other dinosauromorphs, but it comes from much older stratum, estimated to be at least 237 million years old (Ladinian faunal stage of the Middle Triassic).

This newly described specimen establishes that the Dinosauromorpha (dinosaurs and their close ancestors), were present in South America earlier than previously recorded and extends the fossil record of South American dinosauromorphs into the Ladinian stage of the Triassic.

The thigh bone might be small and no genus has been erected based on this single fossil, but it does represent the oldest dinosauromorph fossil found in South America to date.

A skeletal drawing of the Brazilian dinosauromorph (femur shown in white) with a comparison of fossil specimen stratigraphy from Argentina and Brazil which demonstrates the thigh bone represents the oldest evidence of Dinosauromorpha described to date in South America. Picture credit: Müller and Garcia.

Picture credit: Müller and Garcia

An Ecosystem Dominated by Other Reptiles

Based on comparisons with more complete fossil specimens the femur came from an animal around a metre in length, most of which was accounted for by its long, thin tail if this dinosauromorph possessed a similar body plan. It lived in a diverse ecosystem dominated by other types of reptile. For example, the giant pseudosuchian Prestosuchus was probably the apex predator and at nearly 7 metres in length, this giant member of the crocodile-line of the Archosauria would have dwarfed all the dinosauromorphs in the ecosystem.

A life reconstruction of the Brazilian dinosauromorph based on the 11 cm long femur. This ancestor of the Dinosauria would have been dwarfed by other archosaurs in the ancient environment (Prestosuchus). Picture credit: Caetano Soares.

Picture credit: Caetano Soares

For an update on the research into South American dinosauromorphs: A New Silesaurid from South America.

A scale drawing showing the relative sizes of the Brazilian dinosauromorph from the Pinheiros-Chiniquá Sequence compared to Prestosuchus chiniquensis. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The scientific paper: “Oldest dinosauromorph from South America and the early radiation of dinosaur precursors in Gondwana” by Rodrigo T. Müller and Maurício S. Garcia published in Gondwana Research.

Visit the Everything Dinosaur website: Prehistoric Animal Models.

Scientists have identified the first confirmed dinosaur nesting site in Brazil. The fossilised eggs found suggest a colonial titanosaur nesting site and indicate individuals returning periodically to the same location to breed.  A paper has been published in the journal “Scientific Reports”.

The fossils consisting of preserved clutches and isolated egg fragments were excavated from sandy deposits in an abandoned limestone quarry (Lafarge Quarry) at Ponte Alta District, Uberaba Municipality in Minas Gerais State (south-eastern Brazil). The fossils were recovered from the Serra da Galga Formation (Upper Cretaceous) and although no fossilised embryos were found at the site, the shape of the eggs strongly suggest that they were laid by titanosaurs.

Images of selected titanosaurian eggs and egg-clutches collected from the Late Cretaceous Serra da Galga Formation (Bauru Group) at Ponto Alta nesting site, Uberaba Municipality, Minas Gerais State, Brazil. CPPLIP 1798, (a) the best-preserved recovered egg-clutch, bottom view. CPPLIP 1801, (b) isolated egg, with accompanying tomographic slice, showing thickness of the shell and its sedimentary fill. Specimen number CPPLIP 1799, (c) egg-clutch with accompanying tomographic slice, showing thickness of the shell, shells collapsed and its sedimentary fill. The specimen number CPPLIP 1800, (d and e) two eggs found associated. Specimen number CPPLIP 1804 (f) isolated partial egg. Note scale bars 5 cm. Picture credit: Fiorelli et al.

Picture credit: Fiorelli et al

Nesting in Colonies and Evidence of Breeding-site Fidelity

The Titanosauria were a highly successful clade of long-necked, long-tailed herbivores that were globally distributed during the Cretaceous and survived up until the very end of the Mesozoic. Some of the biggest terrestrial animals known to science are members of this clade, dinosaurs such as Patagotitan, Argentinosaurus and Notocolossus. All three of these titanosaurs lived millions of years before the Lafarge Quarry eggs were laid and they lived much further south (higher palaeolatitude).

A scale drawing of the giant titanosaur Patagotitan mayorum commissioned by Everything Dinosaur. This huge dinosaur was estimated to have measured around 35 metres when its fossil bones were initially examined. When Patagotitan was formally named and scientifically described its body size and weight was reduced slightly. However, a reconstructed, life-size skeleton was built measuring 37.2 metres in length. Titanosaurs are amongst the largest terrestrial animals known to science. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Numerous titanosaur nesting sites are known (Spain, Romania, France, India and most notably Argentina), writing in the academic journal “Scientific Reports”, the researchers report the first titanosaur nesting site from the Late Cretaceous of Brazil (Maastrichtian faunal stage). The fossil material consisting of several egg-clutches, partially preserved, isolated eggs and many eggshell fragments were found in two distinct levels, approximately two metres apart.

This discovery adds further support to the theory that these large herbivores nested in colonies and had preferred locations for their nesting sites, what is often referred to as breeding-site fidelity.

To read a related blog post about breeding-site fidelity (philopatry) identified in South American titanosaurs: Two New South American Titanosaurs Described.

The titanosaur egg fossils were found in two distinct layers (L1 and L2) approximately two metres apart. This suggests that this area was a preferred nesting site for titanosaurs. This is the first confirmed dinosaur nesting area found in Brazil. The eggs attributed to titanosaurs also represent the most northerly titanosaurian nesting site known from South America. The discovery of nests located at different levels indicates that titanosaurs returned regularly to preferred nesting areas. Picture credit: Fiorelli et al.

Picture credit: Fiorelli et al

Which Titanosaur Species?

Isolated and fragmentary remains of titanosaur eggs had previously been reported from Brazil, but the Lafarge Quarry specimens provide unambiguous proof of titanosaur nesting in Brazil. As no embryos have been found in association with the fossilised eggs, it is not possible to comment on the specific genus involved.

However, the researchers state that between the Santonian to the Maastrichtian faunal stages of the Late Cretaceous (86 to 66 million years ago) only derived titanosaurs such as saltasaurids and colossosaurians are recorded from South America. It is likely that the fossils associated with the nesting site represent an unknown genus.

Sue from Everything Dinosaur poses in front of the colossal Patagotitan skeleton which is being exhibited at the Natural History Museum (London). Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

During the Late Cretaceous the Ponte Alta District would have been located at around 26 degrees south of the Equator, putting it on a similar palaeolatitude of titanosaur nesting sites found in India. Previously, South American titanosaur nesting sites have been recorded between 33 to 47 degrees south of the Equator. This latitudinal difference could also influence the distribution of species on the Gondwana continent. The palaeoclimatic variation and geological characteristics could result in a difference in nesting time between titanosaurs living at different latitudes.

How Did Titanosaurs Build Nests?

The Lafarge Quarry site indicates colonial nesting which also suggests that these herbivorous dinosaurs moved around in herds. It is likely that Ponte Alta District titanosaurs scooped out pits in the soft sand using their back legs and then laid their eggs in clutches, before burying them and perhaps covering the nest with vegetation to help incubation.

To read an article about the naming of Austroposeidon magnificus the largest dinosaur from Brazil described to date: Brazil’s Biggest Dinosaur.

The scientific paper: “First titanosaur dinosaur nesting site from the Late Cretaceous of Brazil” by Lucas E. Fiorelli, Agustín G. Martinelli, João Ismael da Silva, E. Martín Hechenleitner, Marcus Vinícius Theodoro Soares, Julian C. G. Silva Junior, José Carlos da Silva, Élbia Messias Roteli Borges, Luiz Carlos Borges Ribeiro, André Marconato, Giorgio Basilici and Thiago da Silva Marinho published in Scientific Reports.

The award-winning Everything Dinosaur website: Dinosaur Models.

Scientists including Professor Paul Barrett of the London Natural History Museum have described a new species of basal armoured dinosaur from fossils found in China. The dinosaur named Yuxisaurus kopchicki, represents the first valid and undisputed member of the Thyreophora (armoured dinosaurs) to be described from fossils found in Lower Jurassic Asian strata.

A life reconstruction of the newly described, Early Jurassic Chinese armoured dinosaur Yuxisaurus kopchicki. Picture credit: Yu Chen.

Picture credit: Yu Chen

The Rapid Geographic Spread of Early Armoured Dinosaurs

With an estimated body length of around three metres, Yuxisaurus might be small compared to some of the later and much more famous members of the Thyreophora clade such as Ankylosaurus and Stegosaurus, but confirmation of the presence of early armoured dinosaurs in China underlines the rapid geographic dispersal of these ornithischians. The first armoured dinosaurs are thought to have evolved around 200 million years ago (Hettangian faunal stage of the Early Jurassic). Yuxisaurus fossils consisting of vertebrae, skull bones, elements from the limbs, shoulder blades (scapulae) and 120 osteoderms (bony armour), were excavated from the upper portion of Fengjiahe Formation exposures, near Jiaojiadian village, Yimen County, Yuxi Prefecture, Yunnan Province (southwestern China).

Although the dating of the strata has proved problematical, it is likely that the fossils are somewhere between 192 and 182 million years old (late Sinemurian to early Toarcian stage of the Early Jurassic).

Variety Amongst Early Members of the Thyreophora

Although relatively small compared to later armoured dinosaurs, the limb bones suggest a robust, stout animal indicating that Yuxisaurus had a different body shape compared to other known early thyreophorans such as Scutellosaurus and Emausaurus. This suggests that early armoured dinosaurs had a diverse morphology and ecology and they spread rapidly establishing a wide geographical distribution and filling a variety of niches in Early Jurassic ecosystems.

Skeletal reconstruction of Y. kopchicki showing main preserved elements from the holotype (highlighted in blue). Details of the skull bones (A), cervical vertebrae (B) and dorsal vertebrae (C). The left scapula is shown (D) and the right humerus (E) along with the distal portion of the left femur (F). Note scale bars equal 5 cm for A-C and 10 cm for D-F. Osteoderms have been omitted to show the skeleton. Picture credit: Xi Yao.

Picture credit: Xi Yao

The First Unambiguous Armoured Dinosaur from the Early Jurassic of Asia

First author of the scientific paper, Professor Paul Barrett (Natural History Museum, London), commented:

“Although we’ve had tantalising fragments of early armoured dinosaurs from Asia, this is the first time we’ve had enough material to recognise a new species from the region and investigate its evolutionary history. I hope it’s the first of many new dinosaurs from the localities being discovered by my colleagues in Yunnan.”

Senior author of the paper, Dr Shundong Bi, a professor at Indiana University of Pennsylvania, explained that the dinosaur had been named Yuxisaurus kopchicki in honour of the Yuxi Prefecture, whilst the trivial or species name was in recognition of the work of molecular biologist Dr John J. Kopchick and for his support and funding of a new Indiana University of Pennsylvania science complex which is due to open in autumn 2023.

Dr Shundong Bi stated, that despite its robust body:

“Yuxisaurus was possibly a facultative quadrupedal. It was primarily adapted for walking on four legs, but also able to walk on two legs.”

Where Did Armoured Dinosaurs Originate?

Until recently all the unambiguous Early Jurassic Thyreophora taxa were described from fossils found in North America (Scutellosaurus) or Europe (Emausaurus and Scelidosaurus). This led palaeontologists to conclude that armoured dinosaurs originated in Laurasia, however, new phylogenetic analyses (Butler et al 2020, Boyd 2015, Raven and Maidment 2017, Maidment et al 2020 and Baron et al 2017a) have proposed that Lesothosaurus from southern Africa and Laquintasaura from Venezuela might also represent early members of the Thyreophora. If Lesothosaurus and Laquintasaura are early armoured dinosaurs, then this suggests that this clade could have originated in Gondwana.

Phylogenetic assessments plotting the relationship of Yuxisaurus within the Thyreophora. Analysis (A) modified from Norman (2021) dataset which places Yuxisaurus as a sister taxon to Emausaurus which is known from the Early Jurassic (Toarcian) of Germany. Analysis (B) modified from Maidment et al (2020) places Yuxisaurus within the Thyreophora as an early-diverging branch between Emausaurus and Scelidosaurus which is known from the older sedimentary deposits from Charmouth on the Dorset coast. Picture credit: Yao et al.

Picture credit: Xi Yao et al

The phylogeny of early ornithischians remains disputed, it is hoped that further fossil finds will resolve this debate.

Everything Dinosaur acknowledges the assistance of a media release from the London Natural History Museum in the compilation of this article.

To read an article about the discovery of Laquintasaura: Laquintasaura What Does it All Mean?

The scientific paper: “A new early-branching armoured dinosaur from the Lower Jurassic of southwestern China” by Xi Yao, Paul M. Barrett, Lei Yang, Xing Xu and Shundong Bi preprint via bioRxiv before publication in eLife.

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The trouble with being regarded as the biggest, longest, tallest or oldest when you are newly described species of dinosaur, is that sooner or later another fossil discovery will take this claim away from you. Back in 2019, team members wrote a blog post about the discovery of Adratiklit boulahfa from the Middle Jurassic of Morocco North Africa’s First Stegosaur. The fossils of this armoured dinosaur were estimated to be around 168 million years old (Bathonian faunal stage), making Adratiklit the oldest definitive stegosaur described.

Scientists including Dr Susannah Maidment a senior researcher at the London Natural History Museum, who co-authored the paper describing A. boulahfa, have announced the discovery of an even older stegosaur, this time from China. The new stegosaur named Bashanosaurus primitivus is at least one million years older than the Moroccan stegosaur.

The Fossils of Bashanosaurus

The fossils of Bashanosaurus herald from the Lower Member of the Shaximiao Formation and radiometric dating based on isotope decay analysis using zircon crystals (geochronological data), suggest that the deposits associated with the fossil bones are around 169 ± 0.68 million years of age.

A life reconstruction of the newly described Chinese stegosaur Bashanosaurus primitivus. Picture credit: Banana Art Studio.

Picture credit: Banana Art Studio

Did the Stegosauria Evolve in Asia?

The fossil record of early stegosaurs is highly fragmentary and the evolution of this iconic branch of the Thyreophora is poorly understood. The Stegosauria represents a major clade within the Ornithischia (bird-hipped dinosaurs). Fourteen genera of stegosaur have been described to date and they are both geographically and temporally widespread, known from all the major landmasses except for Australia and Antarctica.

In 2016, a new dinosaur quarry was opened in Yunyang County, Chongqinq Municipality in southwestern China. Stegosaur fossil material was identified on the western side of the quarry. The disarticulated material preserved within the sandstone consisted of a dorsal vertebra, two tail bones (caudal vertebrae), a right scapula, a right coracoid and elements from the hind legs. Three pieces of dermal armour were also discovered at this location (one plate and two spines) along with fragments of rib bones. These fossils (CLGPR V00006-1) are regarded as the holotype of B. primitivus.

Potentially Three Bashanosaurus Specimens

More stegosaur fossils were found at the site approximately fifty metres away from the holotype material (CLGPR V00006-2). They consist of five dorsal vertebrae, a right tibia, a right fibula some ribs and a single piece of dermal armour (one plate). In addition, a single dorsal vertebra (CLGPR V00006-3) was found on the eastern part of the site some one hundred and twenty metres away from the holotype material.

Whilst the researchers have confidently assigned these fossils to the Stegosauria and specifically to Bashanosaurus primitivus, three individual stegosaurs are represented by the bones.

Photograph (A) with interpretative line drawing showing the position of the B. primitivus holotype fossil material (CLGPR V00006-1) on the western side of the wall of dinosaur fossils. Photograph (B) with interpretative line drawing showing the second location with B. primitivus fossil material ((CLGPR V00006-2) towards the middle of the wall of dinosaur fossils. Picture credit: Hui et al.

Picture credit: Hui et al

It is not known whether the fossil bones represent a juvenile or a fully-grown animal. However, based on these bones, the researchers estimate that the largest stegosaur from the quarry was about 2.8 metres in length.

Unique Anatomical Traits

The scientists who include researchers from the Chongqing Bureau of Geological and Mineral Resource Exploration and Development in China and London’s Natural History Museum identified several unique anatomical traits that led to the erection of a new genus. Bashanosaurus possesses anatomical characteristics associated with basal thyreophorans as well as more derived features associated with early stegosaurs. For example, it has a smaller and less developed shoulder blade, the bony projection of the thighbone (fourth trochanter) is positioned below the middle of the shaft and the bases of the armour plates curve outwards and are thicker than the plates on the backs of later stegosaurs.

The genus name is derived from “Bashan” in reference to the ancient name for the area of Chongqing in China where the dinosaur was found. The species moniker is derived from the Latin for “first” – primitivus.

Lead author of the research team, Dr Dai Hui from the Chongqing Bureau of Geological and Mineral Resource Exploration and Development commented:

“All these features are clues to the stegosaurs’ place on the dinosaur family tree. Bashanosaurus can be distinguished from other Middle Jurassic stegosaurs, and clearly represents a new species.”

Phylogenetic Analysis

Phylogenetic analysis shows that Bashanosaurus primitivus is the earliest-diverging stegosaur, along with Chungkingosaurus (C. jiangbeiensis), which is thought to be closely related, although Chungkingosaurus lived much later than Bashanosaurus. Chungkingosaurus fossils are known from the Upper Member of the Shaximiao Formation.

The discovery of Bashanosaurus will help researchers to learn more about the evolution of stegosaurs and supports the theory that this type of armoured dinosaur first appeared in Asia. Although there have been some exciting fossil discoveries helping to improve understanding with regards to the evolution of armoured dinosaurs (Thyreophora), there are still numerous gaps in the fossil record which makes mapping the evolutionary development of these iconic dinosaurs extremely difficult.

For example, Everything Dinosaur recently wrote an article about the discovery of the basal thyreophoran Yuxisaurus kopchicki, whose fossils also come from China. Scientists from the London Natural History Museum also contributed to the scientific paper on Yuxisaurus: The Earliest Armoured Dinosaur Found to Date.

Everything Dinosaur has inserted Yuxisaurus kopchicki within the phylogenetic assessment of Bashanosaurus to help put these recent fossil discoveries into context (see below).

A phylogenetic analysis showing the placement of B. primitivus within the Stegosauria. It is believed to be around one million years older than the recently described Adratiklit boulahfa (Maidment et al) from the Middle Jurassic of Morocco. The earliest armoured dinosaur from Asia known to date (Yuxisaurus kopchicki) from Yunnan Province, China (Yao et al) has been incorporated into the image by Everything Dinosaur to show the approximate phylogenetic and temporal placement of Y. kopchicki when compared to B. primitivus. Picture credit: Hui et al with additional annotation by Everything Dinosaur.

Picture credit: Hui et al with additional annotation by Everything Dinosaur

The Stegosauria Clade Originated in Asia?

Commenting on the phylogenetic assessment Dr Hui stated:

“What’s more, our analysis of the family tree indicates that it [B. primitivus] is one of the earliest-diverging stegosaurs along with the Chongqing Lizard (Chungkingosaurus) and Huayangosaurus. These were all unearthed from the Middle to Late Jurassic Shaximiao Formation in China, suggesting that stegosaurs might have originated in Asia”

An illustration of the Chinese Stegosaur Chungkingosaurus. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The picture (above) shows a drawing of a model from the PNSO model range.

To view this range of prehistoric animal figures: PNSO Age of Dinosaurs Figures.

Co-author of the scientific paper published in the Journal of Vertebrate Paleontology, Dr Susannah Maidment of the London Natural History Museum and an expert in ornithischian dinosaurs added:

“The discovery of this stegosaur from the Middle Jurassic of China adds to an increasing body of evidence that the group evolved in the early Middle Jurassic, or perhaps even in the Early Jurassic, and as such represent some of the earliest known bird-hipped dinosaurs. China seems to have been a hotspot for stegosaur diversity, with numerous species now known from the Middle Jurassic right the way through until the end of the Early Cretaceous period.”

Everything Dinosaur acknowledges the assistance of a media release from the Taylor & Francis Group in the compilation of this article.

The scientific paper: “New Stegosaurs from the Middle Jurassic Lower Member of the Shaximiao Formation of Chongqing, China” by Dai Hui, Li Ning, Susannah C. R. Maidment, Wei Guangbiao, Zhou Yuxuan, Hu Xufeng, Ma Qingyu, Wang Xunqian, Hu Haiqian and Peng Guangzhao published in the Journal of Vertebrate Paleontology.

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