Scientists have named and described a new genus of basal iguanodontian from the Xinlong Formation of southern China. The dinosaur has been named Napaisaurus guangxiensis. It is the first, basal iguanodontian taxa described from southern China.
Holotype fossil material of Napaisaurus (N. guangxiensis) is a right ilium and ischium found in 2020. It is the first, basal iguanodontian taxa from southern China. Picture credit: Ji and Zhang.
Picture credit: Ji and Zhang
Fossils Found in 2020
Partial hip bones (a right ilium and a right ischium) from a single individual animal were discovered in 2020 from excavations undertaken in strata associated with the Aptian-aged, Xinlong Formation of Napai Basin, Fusui County, Guangxi Zhuang Autonomous Region, South China. The dinosaur’s name translates as Napai Basin lizard from Guangxi and its discovery adds to the dinosaur biota (sauropods, spinosaurids and carcharodontosaurids) associated with the Xinlong Formation.
Team members at Everything Dinosaur, estimate that based on the partial hip bones, the Napaisaurus specimen would have been around four metres in length.
A scale drawing of Napaisaurus guangxiensis. This basal iguanodontian is estimated to be around four metres in length. Picture credit: Everything Dinosaur.
Picture credit: Everything Dinosaur
Comparing Dinosaur Biotas from China and North-eastern Thailand
The official journal publication announcing the discovery of this new Early Cretaceous herbivore was published earlier this year, but it was made available on-line in 2021.
The fossils permit an iguanodontian to be added to the dinosaur biota associated with the Xinlong Formation and it provides important evidence helping palaeontologists to better understand the relationship between the Lower Cretaceous fossils of the Napai Basin (Xinlong Formation) and those associated with contemporaneous deposits from northern China and the Khorat Group of north-eastern Thailand. Specifically, the naming of Napaisaurus adds a definitive iguanodontian to the Xinlong Formation biota, thus permitting a more detailed comparison with the ornithischian dinosaurs associated with the Aptian-aged Khok Kruat Formation (the uppermost member of the Khorat Group), from which several iguanodontian ornithopods have been described (Ratchasimasaurus, Siamodon, Sirindhorna).
The scientific paper: “First new genus and species of basal iguanodontian dinosaur (Ornithischia: Ornithopoda) from southern China” by S. Ji and P. Zhang published in Acta Geoscientica Sinica.
Researchers have named the largest pterosaur found to date in South America. The giant Thanatosdrakon (T. amaru) is estimated to have had a wingspan of around nine metres and it would have stood as tall as a giraffe.
Writing in the academic journal “Cretaceous Research”, the scientists, have assigned Thanatosdrakon to the Azhdarchidae family of pterosaurs and postulate that it was closely related to the slightly larger and geologically younger Quetzalcoatlus, fossils of which are known from North America.
The paratype fossil a giant left humerus (UNCUYO-LD 350) is carefully cleaned at the dig site. Picture credit: Reuters/ICB-CONICET/UNCUYO.
Picture credit: Reuters/ICB-CONICET/UNCUYO
One of the Largest Flying Vertebrates Known
The fossil material, thought to represent two individual pterosaurs was found in the upper-most levels of the Plottier Formation (upper Coniacian–lower Santonian, Neuquén Basin), Mendoza, western Argentina. The researchers, who include CONICET* researcher Dr Leonardo Ortiz David, Dr Bernardo González Riga, director of the Laboratory and Museum of Dinosaurs of the Faculty of Exact and Natural Sciences and world-renowned pterosaur expert Dr Alexander Kellner (Director of the National Museum of Rio de Janeiro, Brazil), estimate that Thanatosdrakon lived around 86 million years ago. Based on the single, huge left humerus of the paratype (UNCUYO-LD 350), a wingspan of around 9 metres is proposed, making Thanatosdrakon amaru one of the largest flying vertebrates known to science.
Comparing the estimated wingspans of the paratype and holotype fossil material associated with Thanatosdrakon amaru with large, extant birds. Picture credit: ICB-CONICET/UNCUYO.
Picture credit: Reuters/ICB-CONICET/UNCUYO
Exceptionally Preserved Fossils
A civil construction project had uncovered some of the fossils. A field team was despatched to map the site and to recover the exceptionally well-preserved bones. The fossil material consists of vertebrae and bones from the limbs. As the larger humerus was found in close proximity to the other fossils, the scientists have speculated that this huge animal was social and probably lived in flocks.
Thanatosdrakon is the oldest taxon of the clade Quetzalcoatlinae so far described. As the strata containing the fossil bones represent deposition in a floodplain environment with ephemeral meandering streams and rivers, the researchers conclude that like the much later Quetzalcoatlus, Thanatosdrakon inhabited continental, inland areas.
Skeletal reconstructions of Thanatosdrakon amaru. The holotype fossil material (UNCUYO-LD 307) and the left humerus paratype (UNCUYO-LD 350). Picture credit: ICB-CONICET/UNCUYO.
Picture credit: Reuters/ICB-CONICET/UNCUYO
Important Information on Azhdarchid Anatomy
The fossils are not distorted or flattened to any great degree. Their three-dimensional preservation will help the researchers to learn more about the anatomy of giant pterosaurs. In addition, some of the fossil bones such as the dorsosacral vertebrae and caudal vertebra along with the notarium (the structure formed by fusion of the dorsal vertebrae, seen in pterosaurs and birds), have never been described in giant azhdarchids. The researchers expect that further study of these bones will provide important information on azhdarchid anatomy. Hopefully, new fossil finds will provide more information on the Azhdarchidae.
The “Dragon of Death”
This large pterosaur probably hunted on the ground, perhaps stalking prey in a similar manner to the marabou stork (Leptoptilos crumenifer) which is found in sub-Saharan Africa. The genus name is derived from the Greek words thanatos which means death and drakon (dragon). The species name honours the Inca winged serpent (Amaru).
CONICET* (Consejo Nacional de Investigaciones Científicas y Técnicas [National Council for Scientific and Technical Research of Argentina]).
The scientific paper: “Thanatosdrakon amaru, gen. et sp. nov., a giant azhdarchid pterosaur from the Upper Cretaceous of Argentina” by Leonardo D. Ortiz David, Bernardo J. González Riga and Alexander W. A. Kellner published in the journal Cretaceous Research.
Earlier this spring, a new taxon of alvarezsaurid theropod was described from well-preserved, postcranial remains found in Uzbekistan. The little dinosaur, measuring less than half a metre long, has been named Dzharaonyx eski, which translates as “old Dzharakuduk claw”.
The cat-sized alvarezsaurid theropod Dzharaonyx eski from the Late Cretaceous of Uzbekistan. It is regarded as the geologically oldest member of the Parvicursorinae.
From the Bissekty Formation
Writing in the academic “Journal of Vertebrate Paleontology”, the researchers, including Hans-Dieter Sues (Department of Paleobiology, National Museum of Natural History, Smithsonian Institution, Washington, D.C.), describe this cat-sized theropod based on bones from the spine including dorsal and caudal vertebrae, limb bones, parts of the pelvis and bones from the hand including the iconic, robust alvarezsaurid claws.
Dzharaonyx eski a new taxon of alvarezsaurid from the Late Cretaceous of Uzbekistan. Picture credit: Averianov and Sues.
Picture credit: Averianov and Sues
The fossils come from the Bissekty Formation (Upper Cretaceous, Turonian faunal stage) and D. eski is estimated to have lived around 91-92 million years ago. The dinosaur was named after the type locality (Dzharakuduk in south-central Uzbekistan). The species name “eski” is derived from the Uzbek word for “old”.
Pronounced Zar-ah-ra-on-niks es-key, a phylogenetic analysis of this newly described taxon places it within the alvarezsaurid subfamily the Parvicursorinae alongside other Asian members of the Alvarezsauridae such as Parvicursor (P. remotus) and Qiupanykus (Q. zhangi). Dzharaonyx eski is the oldest member of the Parvicursorinae known to science, it having lived at least 10 million years earlier than related species, fossils of which are confined to the Campanian and Maastrichtian faunal stages of the Late Cretaceous.
Remarkable Alvarezsaurids
Alvarezsaurids were highly specialised theropods, with a single, powerful hand claw adapted for tearing and digging. It is thought that these small maniraptoran dinosaurs fed on colonial insects such as termites.
The Alvarezsauridae family was erected in 1991 (Bonaparte). These long-legged theropods were once thought to be a lineage of flightless birds. Most palaeontologists consider them to be an early diverging branch of the Maniraptora. These dinosaurs tend to be both geographically and temporally widespread.
Recently, another Asian member of the Parvicursorinae was described from partial, postcranial material from the Upper Cretaceous (Campanian) Barungoyot Formation in Mongolia. The alvarezsaurid has been named Ondogurvel alifanovi.
Mike from Everything Dinosaur commented:
“Dzharaonyx is a remarkable fossil discovery. It lived during the Turonian faunal stage of the Cretaceous. We look forward to more dinosaur discoveries from the famous Bissekty Formation.”
The scientific paper: “New material and diagnosis of a new taxon of alvarezsaurid (Dinosauria, Theropoda) from the Upper Cretaceous Bissekty Formation of Uzbekistan” by Alexander O. Averianov and Hans-Dieter Sues published in the Journal of Vertebrate Paleontology.
As the glaciers that comprise the Southern Patagonian Ice Field in Chile retreat, some of the rocks exposed have revealed an astonishing array of ichthyosaur fossils. A resilient and dedicated team of scientists have been working to map this hugely significant site and to extract the marine reptile fossil material so that these remarkable specimens can be studied in more detail.
Dr Judith Pardo-Pérez (University of Magallanes), shows the ichthyosaur specimen exposed by the retreating Tyndall Glacier. Picture credit: Alejandra Zúñiga.
Picture credit: Alejandra Zúñiga
Finding and Rescuing “Fiona” the Pregnant Ichthyosaur
An expedition to the remote Tyndall Glacier located in the Torres del Paine National Park, led by Dr Judith Pardo-Pérez from the University of Magallanes (Punta Arenas, southern Chile), has recovered the country’s first complete ichthyosaur fossil. Nicknamed “Fiona” the four-metre-long specimen represents the remains of a pregnant female, complete with several ichthyosaur embryos.
“Fiona” was discovered in 2009, during an earlier expedition to this remote area of Chilean Patagonia. A team of dedicated researchers which included Jonatan Kaluza from Fundación de Historia Natural Félix de Azara and CONICET (Argentina), biologist and palaeontological excavator Héctor Ortiz from the Chilean Antarctic Institute and the University of Chile and renowned ichthyosaur expert Dr Dean Lomax (Visiting Scientist at The University of Manchester), braved the harsh conditions in March and April to ensure the safe removal of the specimen. The intact female ichthyosaur remains were airlifted using a helicopter. It is hoped that further analysis of this remarkable specimen will confirm it as a new ichthyosaur genus.
A helicopter prepares to airlift the pregnant ichthyosaur specimen. Picture credit: The University of Manchester.
Picture credit: The University of Manchester
The First Female Palaeontologist to Lead a Major Expedition to Patagonia
Dr Judith Pardo-Pérez has visited the Tyndall fossil site more than ten times since the initial discovery in 1997 and completed her PhD on the ichthyosaurs found in the area. Thanks to funding from the Chilean National Agency for Research and Development (ANID), a team of top scientists could be put together to allow the fossils preserved in an ancient Cretaceous seabed to be studied in detail.
Dr Pardo-Pérez, is the first female palaeontologist to lead a major expedition in Patagonia.
Part of the Tyndall Ichthyosaur Team discuss excavating a section of a fossil specimen. Picture credit: The University of Manchester.
Picture credit: The University of Manchester
Collecting these hugely important marine reptile fossils, was no easy task. The Tyndall Glacier site could only be reached by a 10-hour hike or horse ride and the team had to endure difficult weather conditions including high winds and snowstorms whilst excavating the fossils from the extremely hard sediment.
To combat the 90 kph winds, heavy rain and snow, a hangar was built over “Fiona” so that the team could continue to work despite the harsh weather. Circular saws and heavy-duty excavation tools were used to free the fossils from the bedrock.
A hanger was erected over the 4-metre-long ichthyosaur fossil so the scientists could continue working on the specimen despite the extreme weather conditions. Picture credit: The University of Manchester.
Picture credit: The University of Manchester
The Most Abundant and Best-preserved Cretaceous Ichthyosaur Deposit Known
Despite the constant threat of pumas, the team have ensured that this exceptional female specimen has been made available for further analysis and study. It is the only known specimen of a pregnant female of Valanginian-Hauterivian age (between 129 and 139 million years old from the Early Cretaceous).
Commenting on the importance of the specimen, Dr Pardo-Perez Pérez stated:
“At four metres long, complete, and with embryos in gestation, the excavation will help to provide information on its species, on the palaeobiology of embryonic development, and on a disease that affected it during its lifetime.”
In addition to “Fiona” a further twenty-three new ichthyosaur specimens were discovered by the expedition team, making the Tyndall Glacier site perhaps the most abundant and best-preserved early Cretaceous ichthyosaur deposit in the world.
Dr Judith Pardo-Pérez and Dr Dean Lomax examining the best-preserved skull of an ichthyosaur found at the Tyndall Glacier site. Whilst assisting on-site, Dr Lomax found new specimens including the skull of a juvenile ichthyosaur.Picture credit: The University of Manchester.
Picture credit: The University of Manchester
An Ichthyosaur Graveyard
The fossils consist of adults, juveniles and very young ichthyosaurs, they can provide scientists with information on breeding behaviour as well as helping to plot the radiation of new ichthyosaur genera following the end-Jurassic extinction event.
Dr Lomax explained:
“The fact that these incredible ichthyosaurs are so well preserved in an extreme environment, revealed by a retreating glacier, is unlike anywhere else in the world. The considerable number of ichthyosaurs found in the area, including complete skeletons of adults, juveniles, and new-borns provides a unique window into the past. The international collaboration helps to share this exceptional ichthyosaur graveyard with the world and, to a large extent, to promote science.”
Jonatan Kuluza, palaeontological technician at the Fundación de Historia Natural Félix de Azara and CONICET (Argentina), uses a circular saw to cut out an ichthyosaur specimen. Picture credit: The University of Manchester.
Picture credit: The University of Manchester
Dr Lomax added:
“The weather was so extreme that we could not get to the ichthyosaur site every day and had to remain in camp. On those days when the team could reach the site, they documented the ichthyosaurs and other fossils and discovered new specimens. Amazingly, on average, two ichthyosaurs were found every day.”
Protecting and Preserving the Remaining Specimens
The female ichthyosaur nicknamed “Fiona”, will be prepared and studied at the Río Seco Natural History Museum in Punta Arenas. It is hoped that the beautifully preserved specimen will go on public display.
The priority for Dr Pardo-Pérez and her collaborators is to try to preserve as many specimens as possible. The remoteness of the site and the difficult working conditions will hamper any attempts to preserve and protect these remarkable specimens.
Outlining some of the problems facing the team, the doctor stated:
“We have almost a hundred ichthyosaurs in the Tyndall Glacier fossil deposit and many of them, unfortunately, will never be excavated, due to the difficulty of access, being in risk areas [cliff edge], and lack of funds. The ichthyosaurs that will not be excavated need protection and consolidation in situ, as the erosion to which they are being subjected on a daily basis is destroying them.”
Everything Dinosaur acknowledges the assistance of media release from The University of Manchester in the compilation of this article.
A new species of Triassic marine reptile has been described following the discovery of superbly preserved fossils in Yunnan Province (south-western China). Named Honghesaurus longicaudalis it is a member of the Pachypleurosauroidea and it possessed the longest tail of any known pachypleurosaur.
The holotype fossil (IVPP V30380) of the newly described Honghesaurus longicaudalis. Photo (a) and line-drawing (b) of whole specimen. c, cervical vertebra; ca, caudal vertebra; d, dorsal vertebra; s, sacral vertebra. Picture credit: Xu et al.
Picture credit: Xu et al
Writing in the academic journal “Scientific Reports”, the researchers from the Chinese Academy of Sciences, in collaboration with colleagues from the Zhejiang Museum of Natural History and Guizhou University, describe a complete skeleton in the collection of the Institute of Vertebrate Palaeontology and Palaeoanthropology, Chinese Academy of Sciences (specimen number IVPP V30380). The stunning fossil material comes from marine deposits associated with the Guanling Formation and it is estimated to be around 244 million years of age (Anisian stage of the Middle Triassic).
The Tale of a Very Long Tail
Remarkably, the tail of H. longicaudalis contains 69 caudal vertebrae, far more than any other known pachypleurosaur, other pachypleurosaurs commonly have no more than 58 caudal vertebrae. Humans in comparison have just 33 vertebrae in their skeleton. The researchers conclude that this extremely long tail (making up more than fifty percent of the entire body length), in combination with the animal’s long trunk made Honghesaurus extremely manoeuvrable in water. The scientists also speculate that the exceptionally long tail and body helped this marine reptile to conserve energy as it swam.
Skull and mandible of Honghesaurus longicaudalis (IVPP V30380). Photo before (a) and after (b) dusted with ammonium chloride. (c) Line- drawing. (d) Reconstruction in dorsal view. an, angular; ar, articular; at, atlas; ax, axis; c, cervical vertebra; den, dentary; en, external naris; eo, exoccipital; f, frontal; j, jugal; m, maxilla; n, nasal; op, opisthotic; p, parietal; pat, proatlas; pm, premaxilla; po, postorbital; pof, postfrontal; prf, prefrontal; pt, pterygoid; q, quadrate; sa, surangular; so, supraoccipital; sq, squamosal; stf, supratemporal fossa. Picture credit: Xu et al.
Picture credit: Xu et al
The Dispersal of the Pachypleurosaurs
The holotype and currently only known specimen of H. longicaudalis (IVPP V30380) measures 47.1 cm in length. Most pachypleurosaurs were of a similar size although phylogenetic analysis suggests that Honghesaurus was closely related to the much larger Wumengosaurus delicatomandibularis, which had an estimated body length of 1.3 metres.
Pachypleurosaurs are regarded as basal members of the Superorder Sauropterygia, which includes placodonts and the plesiosaurs. The research team postulate that the discovery of Honghesaurus demonstrates the diverse morphology of the Pachypleurosauridae and lends weight to the idea that these marine reptiles originated in Europe and dispersed along the Tethys Ocean in a westerly direction giving rise to new forms in the eastern Tethys Ocean.
The best-known of all the pachypleurosaurs is Keichousaurus. It is also known from south-western China although from geologically younger deposits than the strata that yielded the single specimen of Honghesaurus.
The picture (above) shows a PNSO Keichousaurus model. To view the range of PNSO prehistoric animal models: PNSO Age of Dinosaurs Figures.
The scientific paper: “A long-tailed marine reptile from China provides new insights into the Middle Triassic pachypleurosaur radiation” by Guang-Hui Xu, Yi Ren, Li-Jun Zhao, Jun-Ling Liao and Dong-Hao Feng published in Scientific Reports.
Horsetails (sphenopsids) continue to thrive although their Carboniferous heyday is long behind them. Once a much more extensive group, these vascular plants, believed by many palaeobotanists to be closely related to ancestral ferns, are now represented by about twenty species, all contained in the genus Equisetum.
Admiring Horsetails – One of Natures Great Survivors
Horsetails (Equisetum) continue to thrive as they are able to grow in areas where other plants would find it difficult to get a foothold. Often regarded as weeds, these tough little plants are essentially living fossils, as the earliest examples of the genus Equisetum date from the Early Jurassic of South America. Picture credit: Everything Dinosaur.
When team members at Everything Dinosaur see a clump of horsetails, often growing on waste ground we stop to admire them. These tough little plants deserve respect. After all, they are essentially a living fossil, the oldest fossil remains of modern horsetails (genus Equisetum), date from approximately 190 to 182 million years ago (early Pliensbachian to early Toarcian), represented by Equisetum dimorphum from the Early Jurassic of South America (Chubut Province, Argentina).
Photographs of Equisetum dimorphum sp. nov. from the Lower Jurassic of Chubut Province, Argentina. 1-2. Part and counterpart of a strobilus showing the hexagonal sporangiophores and the long leaves of MPEF-Pb 5894a and MPEF-Pb 5894b; 3. Detailed inner view of 1 showing oblong sporangia of MPEF-Pb 5894a; 4. Isolated external cast of sporangiophore showing central umbo of MPEF-Pb 6477a. Abbreviations: le, leaves; s, sporangia. Scale bars 1-2 = 3mm; 3 = 1 mm; 4 = 0.5 mm. Picture credit: Elgorriaga et al.
Scientists have named a new species of therizinosaur based on fragmentary remains found on the Japanese island of Hokkaido. The dinosaur has been named Paralitherizinosaurus japonicus, it is the first recovered from Asian marine deposits and the third example of a therizinosaur to be found in Japan.
The fossil material, recovered from the lower Campanian Osoushinai Formation near to the town of Nakagawa in the Hokkaido Prefecture, was previously identified as a maniraptoran theropod dinosaur, possibly therizinosaur, but its taxonomic status remained uncertain. A group of scientists including Yoshitsugu Kobayashi and Anthony R. Fiorillo from the Hokkaido University Museum re-examined the fossils and erected a new taxon confirming the fossil material did represent a Late Cretaceous member of the Therizinosauridae.
A life reconstruction of the Late Cretaceous, Japanese therizinosaur Paralitherizinosaurus japonicus. Picture credit: Masato Hattori.
Evolution of Claw Shape in the Therizinosauridae
Writing in the academic journal “Scientific Reports”, the researchers reassessed the fossil material consisting of a single vertebra plus bones and claws (unguals) from the right hand. As well as concluding that the fossils represent a therizinosaur, they confirmed that it is the geologically youngest therizinosaur known from Japan described to date.
Paralitherizinosaurus japonicus silhouette showing estimate of body size and position of known skeletal elements. The fossilised claw elements shown in close view with known material in white. Picture credit: Genya Masukawa.
Important Implications for Claw (Ungual) Evolution in the Therizinosauridae
The scientists compared the shape of the hand claws from Paralitherizinosaurus japonicus with the claws from geologically older therizinosaurs and they postulated that that primitive therizinosaurs had claws with generalist functionalities and that the claws of more derived, later therizinosaurs such as P. japonicus were more suited to the hook-and-pull feeding function. Hook-and-pull feeding involves the use of the claws to help gather vegetation and bring it closer to the mouth.
What’s in a Name?
The fossils were found in a concretion associated with the Campanian-aged Osoushinai Formation of the Yezo Group on Hokkaido Island. The Yezo Group mostly consists of marine deposits and many vertebrate fossils such as plesiosaurs, sharks, mosasaurs and turtles have been discovered. Fragmentary dinosaur fossils are also associated with these strata including hadrosaurids, an armoured dinosaur (nodosaurid) and a potential tyrannosaur. A therizinosaur taxon can now be added to this Late Cretaceous dinosaur biota.
The discovery of the bones and claw elements in marine deposits helped to inspire this dinosaur’s scientific name. The genus name translates as “scythe reptile by the sea”, whilst the species name honours Japan.
The concretion that contained the fragmentary therizinosaur fossil material prior to preparation. Picture credit: Kobayashi et al.
The scientific paper: “New therizinosaurid dinosaur from the marine Osoushinai Formation (Upper Cretaceous, Japan) provides insight for function and evolution of therizinosaur claws” by Yoshitsugu Kobayashi, Ryuji Takasaki, Anthony R. Fiorillo, Tsogtbaatar Chinzorig and Yoshinori Hikida published in Scientific Reports.
Fragmentary bones excavated from Santa Cruz Province, Patagonia (Argentina), have revealed the presence of a super-sized megaraptorid theropod in the Late Cretaceous (Maastrichtian faunal stage). The new dinosaur, named Maip macrothorax is estimated to have been at least 9.5 metres long. It represents the biggest member of the Megaraptoridae described to date and its discovery lends support to the theory that these types of dinosaurs were not members of the Allosauria clade, but they were coelurosaurs and therefore related to the dinosaur lineage that gave rise to the birds.
Silhouette of Maip macrothorax showing the preserved bones in white (A). Reconstruction of the thoracic cavity of Maip (B) at the level of dorsal vertebra 6 (D6). Drawing of the excavation of Maip showing the original disposition of the bones (C). Abbreviations: a, axis; c, coracoid; ind, indeterminate bone; g, gastralia; r, rib; v, vertebrae. Picture credit: Rolando et al. Note scale bar in (A) = 1 metre, and (B,C) 50 cm.
Picture credit: Rolando et al
The fossil material was collected from exposures of the Chorrillo Formation approximately eighteen miles southwest of the city of El Calafate (southwestern Santa Cruz Province, Patagonia, Argentina).
The “Shadow of the Death” which “Kills with Cold Wind”
The Megaraptora clade are mostly known from fragmentary and very incomplete specimens. The fossils of Maip macrothorax (pronounced my-eep mac-row-thor-ax), although representing only a small portion of the overall skeleton, consist of a single cervical vertebra (C2 the axis), several dorsal vertebrae, ribs, the left coracoid, a partial toe bone, fragments of the scapula and caudal vertebrae.
By studying these bones the researchers, that included Alexis M. Aranciaga Rolando from the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” (Buenos Aires, Argentina) and Makoto Manabe from the National Museum of Nature and Science (Japan), postulate that the Megaraptora are not archaic members of the Allosauroidea but members of the Coelurosauria clade, that group of theropods more closely related to birds than they are to other members of the Avetheropoda lineage.
Maip macrothorax
The genus name is from the native Aónikenk people of Patagonia (known as the Tehuelche in western culture). Maip is an evil spirit said to roam the Andes and its name means “the shadow of death” which “kills with cold wind”. The specific name derives from the Latin for big thorax. The rib bones indicate that this dinosaur was deep chested with a large thoracic cavity more than 1.2 metres in width.
The second neck bone of Maip macrothorax (axis – C2) shown in lateral (A), anterior (B), posterior (C) and dorsal (D) with accompanying line drawings. Note scale bar = 5 cm. Picture credit: Rolando et al.
Picture credit: Rolando et al
The researchers propose that with the extinction of the carcharodontosaurids, many of which were apex predators on the southern continents, the megaraptorids evolved becoming larger, heavier and more robust, eventually filling the niche of top predator in many parts of the Southern Hemisphere during the Late Cretaceous.
Evolutionary trends of the Megaraptora. Evolutionary trends of Megaraptora. Temporal scale and bars depicting currently known temporal distributions of Megaraptora and Carcharodontosauridae (A). Time-calibrated phylogeny of megaraptoran taxa (B), showing most relevant genera from Asia (black bars), Australia (red bars) and South America (blue bars). Main synapomorphies supporting each node are indicated by arrows. Tree topology follows the results of the present work. Curve showing the increasing in average body size of megaraptorans during Barremian faunal stage through to the Maastrichtian (C). Picture credit: Rolando et al.
Picture credit: Rolando et al
The Rise of the Megaraptorids
Around 94 million years ago (Cenomanian faunal stage of the Late Cretaceous), there was a global extinction event which led to the demise of the Carcharodontosauridae. As far as Everything Dinosaur team members are aware, there are no reliable fossil records for the presence of carcharodontosaurids in South America beyond the Turonian faunal stage (the stage that followed the Cenomanian). An absence of apex predators permitted the megaraptorids and the abelisaurids to evolve to fill this niche in the Southern Hemisphere, whilst the tyrannosaurids become bigger and occupied the apex predator role in Asia and North America.
Maip macrothorax estimated at around 9.5 metres in length, lived some sixteen million years after the next largest megaraptorid (Aerosteon – A. riocoloradense). The body size of megaraptorids during the Early Cretaceous when the carcharodontosaurids still roamed seems to have been limited to around six metres in length, suggesting that these theropods were secondary predators. However, with the extinction of the carcharodontosaurids, body size in the Megaraptoridae increased and by the very end of the Cretaceous (Maastrichtian faunal stage), a body length in excess of ten metres seems plausible.
Helping to Resolve the Phylogeny of these Enigmatic Theropods
Although the bones only represent a small part of the total skeleton and no cranial material has been identified, Maip macrothorax is the most informative megaraptoran known from the Maastrichtian stage. Phylogenetic analysis has placed this new taxon together with other South American megaraptorans in a monophyletic clade (they shared a single, common ancestor), whereas Australian and Asian members constitute successive stem groups.
A leggy, Late Cretaceous carnivore (Murusraptor). Picture credit: Jan Slovak (University of Alberta).
Picture credit: Jan Sovak (University of Alberta).
The researchers propose that the South American megaraptorids differ from more basal megaraptorans such as Fukuiraptor from Japan and Australovenator from Queensland, Australia in several anatomical features and the South American lineage evolved into much bigger, more robust and powerful predators.
The scientific paper: “A large Megaraptoridae (Theropoda: Coelurosauria) from Upper Cretaceous (Maastrichtian) of Patagonia, Argentina” by Alexis M. Aranciaga Rolando, Matias J. Motta, Federico L. Agnolín, Makoto Manabe, Takanobu Tsuihiji and Fernando E. Novas published in Scientific Reports.
Scientists from John Hopkins University (Baltimore, Maryland), Smith College (Northampton, Massachusetts) along with bryozoan expert Paul Taylor of the London Natural History Museum and another collaborator have published a paper in “Science Advances” reporting a possible earliest occurrence of palaeostomate bryozoans.
Cut slabs of bryomorph fossils from the Harkless Formation (Gold Point, Nevada). Cross-sectional view showing round individual tubes (A). Longitudinal cut through organism showing growth form (B). Picture credit: Note scale equals 1,000 microns. Pruss et al.
Picture credit: Pruss et al
Fossils from the Harkless Formation (Nevada) – A Mineralised Bryozoan
Recently, Everything Dinosaur published a blog post about a scientific paper that came out late last year (October 2021), the study reported upon the identification a soft-bodied bryozoan Protomelission gatehousei from Early Cambrian strata: Early Cambrian Origin for the Bryozoa. The oldest previously accepted skeletal bryozoans occur in Lower Ordovician deposits, however, these researchers suggest that fossils found in strata from the Harkless Formation (Nevada, USA) are also bryozoans. The fossils show a radiating form preserved in limestone deposited during the Cambrian. If these fossils also represent bryozoans, they have a hard, mineralised skeleton.
Thin section images of a single bryomorph organism from the Harkless Formation (Nevada). General fossil view (A). Sketches of the branching of daughter tubes from parent tubes (B). Note the formation of distinct skeletal walls from the parent during budding. Note scale bar equals 1 mm. Picture credit: Pruss et al.
Picture credit: Pruss et al
All Skeletal Marine Invertebrate Phyla Appeared During the Cambrian Explosion
Previously, it had been thought that all skeletal marine invertebrate phyla appeared during the Cambrian explosion, except for Bryozoa with mineralised skeletons which were known from fossils dating from the Early Ordovician. If the small fossils identified in thin cross sections of Harkless Formation limestone are examples of bryozoans with a hard skeleton, then this evidence, in addition to the recent paper on the soft-bodied Cambrian bryozoan Protomelission (P. gatehousei), suggests an Early Cambrian origin for the Bryozoa and provides evidence to support the hypothesis that all types of skeletal marine invertebrate phyla evolved during the Cambrian.
If the Nevada fossils are confirmed as bryozoans, the appearance of a mineralised skeleton in this phylum would be pushed back by some 30 million years.
The scientific paper: “The oldest mineralized bryozoan? A possible palaeostomate in the lower Cambrian of Nevada, USA” by Sara B. Pruss, Lexie Leeser, Emily F. Smith, Andrey Yu. Zhuravlev and Paul D. Taylor published in Science Advances.
Bryozoans, also referred to as the Polyzoa, are an ancient phylum of tiny aquatic invertebrate animals that mostly live in colonies. Normally marine, but some species do live in freshwater, they have a protective exoskeleton made from calcium carbonate. They have a special feeding appendage called a lophophore, which resembles a crown of tentacles used for filter feeding.
Bryozoan fossils are abundant and geographically widespread and the presence of six major orders of bryozoans in Lower Ordovician strata strongly indicated that these organisms evolved during the Cambrian, however, fossil evidence was lacking. Late last year (2021), a team of researchers published a paper in the academic journal “Nature” describing a new genus of soft-bodied bryozoan from the Early Cambrian of Australia and southern China. Named Protomelission gatehousei, its fossils confirm a Cambrian origin for these important aquatic organisms.
Protomelission gatehousei from the Cambrian Wirrealpa Limestone, South Australia. Picture credit: Zhang et al.
Picture credit: Zhang et al
A Basal Member of the Bryozoa
The researchers from Macquarie University (Sydney, Australia), the Northwest University (Xi’an, China), the London Natural History Museum, the University of Missouri, the Nanjing Institute of Geology and Palaeontology (Nanjing, China) as well as the Swedish Museum of Natural History (Stockholm, Sweden), describe this new genus as a basal member of the order.
The discovery of a stem bryozoan from rocks dating from the Cambrian narrows the origination gap that previously existed between the known fossil record and independent molecular clock estimates. The researchers state that this fossil discovery pushes back the fossil record of the Bryozoa by approximately thirty-five million years.
Protomelission gatehousei confirms that the colonial body plan of the Bryozoa originated in the Early Cambrian. It also reconciles the fossil record with molecular clock estimations of an Early Cambrian origination and subsequent Ordovician radiation of Bryozoa following the acquisition of a carbonate skeleton.
Fossils of a branching bryozoan colony from the Ordovician. The presence of six major orders of bryozoans in lower Ordovician rocks strongly suggests a Cambrian origin for the largest and most diverse lophophorate phylum but the fossil evidence had been lacking. A newly published paper describes Protomelission gatehousei from the Early Cambrian of Australia and southern China and confirms a Cambrian origin for these important aquatic organisms.
Whilst the Cambrian and Ordovician forms are extinct, modern bryozoans are an important constituent of modern-day marine fauna.
The scientific paper: “Fossil evidence unveils an early Cambrian origin for Bryozoa” by Zhiliang Zhang, Zhifei Zhang, Junye Ma, Paul D. Taylor, Luke C. Strotz, Sarah M. Jacquet, Christian B. Skovsted, Feiyang Chen, Jian Han and Glenn A. Brock published in Nature.
