All about dinosaurs, fossils and prehistoric animals by Everything Dinosaur team members.
Articles, features and information which have slightly more scientific content with an emphasis on palaeontology, such as updates on academic papers, published papers etc.
The global coronavirus pandemic (COVID-19) has touched the lives of nearly everyone on the planet. The measures in place to help restrict the spread of this highly infectious and pernicious disease have had a profound effect. As some restrictions are lifted, one area of science is trying to get back to near normal working practices. Fieldwork for a number of institutions and universities is beginning to commence once again, although with strict hygiene and social distancing measures in place.
Research Projects Commencing Around the World
Fieldwork has commenced as scientists in the Northern Hemisphere hope to make the best of the summer weather. However, great care will have to be taken with regards to personal hygiene and social distancing. Close proximity working as seen here, is going to have to be re-visited and many dig sites and workstations will need to be reorganised.
Scientists, like many in the rest of the population have got used to remote conference calls, webinars, Facebook discussion groups and Zoom calls. Fieldwork will still have to be carried out and in many cases, fossils exposed on the surface, if they are not collected quite quickly, can soon be eroded away once exposed to the elements.
Field teams exploring fossil sites in the Northern Hemisphere hope to make the best of the warm summer weather. Great care will have to be taken with regards to social distancing and personal hygiene. Occupying adjacent workstations at a dig site, will have to be carefully considered, as will the need to share tools, water bottles, tents and such like. Organising fieldwork involves a great deal of planning. Under the current difficulties, these plans are going to have to be even more comprehensive.
Organising Fieldwork is Going to be Even More Challenging
University of Wales Trinity Saint David (UWTSD) – Lampeter campus working at the Neolithic dig site. Fieldwork is going to have to be carefully managed under COVID-19 restrictions.
Picture credit: University of Wales Trinity Saint David (UWTSD)
A spokesperson from Everything Dinosaur commented:
“Having carefully reviewed the current guidelines, we have reluctantly cancelled all our planned fieldwork operations for the rest of this year. This has been a tough decision to make, but in the interests of all the staff and the wider community, we felt it was the right thing to do.”
We wish all those academics, commercial fossil hunters, students and volunteers about to embark on fieldwork, every success with their endeavours. Stay safe, keep well.
Primoptynx poliotauros – Large Owl that Hunted like a Hawk!
With the extinction of the non-avian dinosaurs some 66 million years ago, our mammalian ancestors diversified and thrived. A large proportion of their predators had become extinct and this may have contributed to their success. However, our furry friends were not to have everything go their way, as within a few million years other vertebrates, notably the birds had themselves diversified and begun to fill predatory niches in terrestrial ecosystems once occupied by less derived maniraptorans.
Primoptynx poliotauros
For example, a new species of large owl has been described from postcranial remains found in the Bighorn Basin of Wyoming. This owl, which was approximately sixty centimetres tall, has particularly large and well developed talons on its hind and second toes. Writing in the “Journal of Vertebrate Palaeonotology”, the research team responsible for describing the fossil material conclude that this large bird was a very dangerous threat to the numerous species of small and medium sized mammals within the ecosystem. The owl has been named Primoptynx poliotauros.
The Fossil Remains of Primoptynx poliotauros Laid Out in Skeletal Position
Primoptynx poliotauros fossil bones laid out in approximate skeletal position. Note the scale bar of 10 cm.
Picture Credit: Senckenberg Research Institute/Tränkner
Big Owl with Big Talons
Lead author of the scientific paper, Dr Gerald Mayr, an ornithologist at the Senckenberg Research Institute and Natural History Museum Frankfurt commented:
“The fossil owl was about the size of a modern snowy owl (Bubo scandiacus). However, it is clearly distinguished from all extant species by the different size of its talons. While in present-day owls the talons on all toes are approximately the same size, Primoptynx poliotauros has noticeably enlarged talons on its hind toe and second toe.”
The scientists postulate that as this prehistoric owl has a longer first and second toe, as seen in extant hawks and other members of the Accipitridae family, such as such as the Harpy eagle (H. harpyja), this suggests that P. poliotauros used its feet to dispatch prey items in a hawk-like manner, in contrast to extant owls that kill prey with their beak.
Co-author of the paper, Dr Thierry Smith (Royal Belgian Institute of Natural Sciences), explained:
“Owls today have four toes with claws of equal size to catch relatively small preys and kill them with the beak. Primoptynx poliotauros has a longer first and second toe, as seen in hawks and other members of the family Accipitridae. Those more developed toes are used to pin down prey, which are punctured by the talons. So, it was an owl that hunted like a hawk on medium-sized mammals.”
From the Willwood Formation (Wyoming, USA)
The fossil material heralds from the Willwood Formation of the northern Bighorn Basin, Park County in Wyoming and the genus name is from the Latin for first “primus” and the “ptynx” for owl. Although around 55 million years old, Primoptynx was not the “first owl”, there is evidence to suggest that these birds originated in the Cretaceous.
The fossils help to confirm the widespread and diverse species of owls that were present during the Eocene Epoch. The success of owls (Strigiformes), runs in conjunction with the evolutionary development of placental mammals. The later extinction of Primoptynx poliotauros and prehistoric proto-owls may have been due to the emergence of diurnal birds of prey in the Late Eocene.
Everything Dinosaur acknowledges the assistance of a media release from the Royal Belgian Institute of Natural Sciences in the compilation of this article.
The scientific paper: “Skeleton of a new owl from the early Eocene of North America (Aves, Strigiformes) with an accipitrid-like foot morphology” by Gerald Mayr, Philip D. Gingerich and Thierry Smith published in the Journal of Vertebrate Paleontology.
Study Suggests that Ornithischian and Saurischian Dinosaurs Evolved Around the Same Time
An international team of scientists from Brazil and Argentina in collaboration with a geochronologist from the Massachusetts Institute of Technology (MIT), have provided evidence to support the hypothesis that the Ornithischia and Saurischia diverged early on in dinosaur evolution and this supports the view of the dinosaur family tree as proposed by Seeley in 1887.
Writing in the journal “Scientific Reports”, the researchers which included Jahandar Ramezani (MIT), re-examined the fossils of Pisanosaurus mertii, dating these fossils to approximately 229 million years ago (Late Carnian stage of the Triassic). Pisanosaurus is believed to be the earliest known ornithischian dinosaur, although some palaeontologists have concluded that this one-metre-long reptile is a dinosauriform.
An Analysis of Dinosaur Evolution
This new date suggests that bird-hipped dinosaurs were evolving at around the same as lizard-hipped forms (Saurischia), this challenges the hypothesis proposed by Baron et al in their 2017 paper which re-shaped the traditional view of dinosaur taxonomy.
A View of the Ischigualasto Formation (Foreground)
The famous Ischigualasto Formation (foreground), the Sierra de Famattina Mountains can be seen on the horizon (La Rioja province – Argentina).
Picture credit: Desojo et al
Accurately Dating the Ischigualasto Formation
The researchers focused their fossil finding efforts on the Hoyado del Cerro Las Lajas area, where outcrops of the Ischigualasto Formation can be found, but they are less well explored compared to contemporaneous strata within the “Valley of the Moon” geological park in San Juan Province. Volcanic deposits yielded zircons at various levels and these minerals permitted the measurement of isotopes of uranium and lead (rate of radiometric decay).
The presence of these igneous rocks allowed the geochronologist to measure the relative proportion of isotopes present in the zircon crystals. Radiometric dating permitted the scientists to make an estimate of the age of the bedding planes and infer the age of the fossils that they contain. The study revealed that the Ischigualasto Formation overlaps with the deposition of another important fossil-bearing formation found in North America – the Chinle Formation.
Carefully Jacketing a Specimen Prior to its Removal
A researcher carefully prepares a field specimen for removal.
Picture credit: Desojo et al
Overlapping with the Chinle Formation of the South-western United States
The middle layers of the Chinle Formation which outcrops in the south-western part of the USA contain a variety of vertebrate fossils, including early dinosaurs. However, very few fossils if any, are associated with the lower levels of the Chinle Formation. The lack for fossils, prevents palaeontologists from understanding more about the early radiation and diversity of the Dinosauria from their suspected origins in the southern hemisphere. The rocks from which fossils of the basal ornithischian dinosaur Pisanosaurus have been found were dated to approximately 229 million years ago. From this data, the research team were able to conclude that the earliest bird-hipped dinosaurs evolved at around the same time as the first lizard-hipped dinosaurs appear in the fossil record.
The Scientists Proposed that Pisanosaurus was Indeed an Ornithischian and it Lived Around 229 Million Years Ago
A life reconstruction of the Triassic ornithischian Pisanosaurus.
Dating of the Strata to Determine Dinosaur Evolution
Commenting on the contribution of the dating of the strata to the paper, Jahandar Ramezani stated:
“We can now say the earliest ornithiscians first showed up in the fossil record roughly around the same time as the saurischians, so we shouldn’t throw away the conventional family tree. There are all these debates about where dinosaurs appeared, how they diversified, what the family tree looked like. A lot of those questions are tied to geochronology, so we need really good, robust age constraints to help answer these questions.”
Uranium-bearing Zircon Crystals Allowed an Accurate Date for Parts of the Ischigualasto Formation to be Established
Microscopic crystals of the uranium-bearing mineral zircon were identified in rock samples and these crystals permitted an accurate date for the rock layers to be calculated.
Picture credit: Desojo et al
Everything Dinosaur acknowledges the assistance of a media release from the Earth, Atmospheric and Planetary Sciences department of MIT in the compilation of this article
The scientific paper: “The Late Triassic Ischigualasto Formation at Cerro Las Lajas (La Rioja, Argentina): fossil tetrapods, high-resolution chronostratigraphy, and faunal correlations” by Julia B. Desojo, Lucas E. Fiorelli, Martín D. Ezcurra, Agustín G. Martinelli, Jahandar Ramezani, Átila. A. S. Da Rosa, M. Belén von Baczko, M. Jimena Trotteyn, Felipe C. Montefeltro, Miguel Ezpeleta and Max C. Langer published in Scientific Reports.
Trierarchuncus prairiensis – The Last Alvarezsaurid
A new species of alvarezsaurid dinosaur has been described from fragmentary remains consisting of a foot bone, a partial radius (arm bone) and three thumb claws which might represent a progressive size series. The little dinosaur has been named Trierarchuncus prairiensis and the fossils come from the uppermost Maastrichtian Hell Creek Formation of Montana and demonstrate that these bizarre, little theropods survived until the very end of the Cretaceous.
A Life Reconstruction of the Newly Described Alvarezsaurid T. prairiensis
Trierarchuncus prairiensis life reconstruction.
Picture credit: Badlands Dinosaur Museum (North Dakota) model created by Boban Filipovic
The Most Complete Alvarezsaurid Claw Described to Date
Writing in the journal “Cretaceous Research”, the research team that includes lead author Dr Denver Fowler (Badlands Dinosaur Museum), describe the three thumb claws (manual digit 1) which are of different sizes. They conclude that these three claws probably represent a growth series and from this they can plot how the claw changed as the alvarezsaurid grew. As Trierarchuncus matured, the thumb claw became more robust and roughened.
Blood vessel grooves on the manual ungual (claw) became more deeply embedded in the bone. One claw, the middle-sized specimen, represents the most complete alvarezsaurid thumb claw described to date and it demonstrates that these claws were more curved than previously thought. A powerful, strongly curved thumb claw would have helped this small dinosaur to rip into rotten wood in search of invertebrates. It has also been suggested that alvarezsaurids evolved to exploit termites as a food source, that is, they exhibited termitophagy (specialised consumers of termites). The single claw on each hand in association with strong forelimbs could have been used to tear apart termite nests.
A View of the Three Alvarezsaurid Fossil Claws (Proposed Ontogenetic Series)
The three claws described in the scientific paper form a possible growth series. The most complete alvarezsaurid claw described to date can be seen in the middle. Note the strongly curved and hook-like claw, if this is a growth series, then it has been suggested that the thumb claw became more strongly curved as the animal matured.
Picture credit: Badlands Dinosaur Museum (North Dakota)
Inspired by Captain Hook!
The claws were the inspiration behind the dinosaur’s name. The genus name comes from the Greek “trierarch”, a reference to the appointed officers responsible for a Greek warship, whilst “uncus” is the Latin for hook. The trivial or species name honours the gentle, rolling prairies of eastern Montana where the fossils were found. The name which is pronounced Try-er-arch-unk-cus pray-ree-en-sis translates as “Captain Hook of the prairies”. This is also a nod in the direction of the infamous “Captain Hook”, a fictional character, the nemesis of Peter Pan created by J. M. Barrie.
The Three Thumb Claws from the Alvarezsaurid in the Study
Possible evidence of a growth series – alvarezsaurid manual unguals. The human hand provides a scale, an adult Trierarchuncus was probably less than a metre in length.
Picture credit: Badlands Dinosaur Museum (North Dakota)
Implications for the Taxonomy and Phylogeny of the Alvarezsauroidea
If the three claw specimens do indeed represent a growth series (an ontogenetic series), then this discovery could have far-reaching consequences for all those maniraptoran dinosaurs confined within the Alvarezsauroidea. If the claws of these dinosaurs changed radically as the animal grew and matured, then supposedly unique features (autapomorphies), used to erect other alvarezsaurid genera might be unreliable. These features might be attributed to the relatively young age of the dinosaur when it died, rather than representing a defining anatomical characteristic that can lead to the naming of a new species.
Views of the Thumb Claw Showing Curvature (MOR 6622 – Holotype Claw)
Views of the most complete Trierarchuncus thumb claw showing curvature. The holotype claw MOR 6622.
Picture credit: Badlands Dinosaur Museum (North Dakota)
The Youngest Known Alvarezsaurid
Stratigraphic data indicates that Trierarchuncus represents the youngest known alvarezsaurid. Fossils associated with these types of theropod occur through most of the eighty-five metre thick Hell Creek Formation, with the uppermost specimen having been found within a few metres of the contact with the Palaeocene-aged Fort Union Formation. It is likely that alvarezsaurids were present in North America throughout the Late Cretaceous and that they persisted until the extinction of the non-avian dinosaurs.
The scientific paper: “Trierarchuncus prairiensis gen. et sp. nov., the last alvarezsaurid: Hell Creek Formation (uppermost Maastrichtian), Montana” by Denver W. Fowler, John P. Wilson, Elizabeth A. Freedman Fowler, Christopher R. Noto, Daniel Anduza and John R. Horner published in Cretaceous Research.
Evidence of Sequential Moult Identified in Microraptor gui
A team of Israeli scientists in collaboration with colleagues from China have found evidence in the holotype specimen of Microraptor (Microraptor gui) that this flying dinosaur sequentially moulted its feathers. All living birds have to replace their feathers periodically in order to maintain their function, feathered dinosaurs underwent the same process to. The way in which the feathers are shed and replaced provides palaeontologists with an opportunity to infer habits and behaviours about a long extinct animal.
The Holotype Fossil Material of Microraptor gui
Feathers are found preserved in many dinosaur fossils from China and a new study suggests that Microraptor sequentially moulted which has implications for the habit and behaviour of this volant dromaeosaurid.
Writing in the academic journal Current Biology, the scientists from the University of Haifa, the Society of Protection of Nature and the Jerusalem Bird Observatory (Israel), along with co-workers from the Chinese Academy of Sciences identified signs of sequential moulting on the fossilised wing of Microraptor gui.
Moulting Strategy Links to Habitat Selection and Flight Ability
Living birds generally moult their feathers in one of three main ways or strategies:
1). A gradual direct replacement of all flight feathers in a slow moult with both wings showing similar stages of moult at the same time – referred to as sequential moulting.
2). Simultaneous replacement of all the flight feathers – referred to as simultaneous moulting.
3). A gradual, but not ordered moult in which feather replacement has no predictable sequence or direction – referred to as an irregular moult.
Different Moulting Strategies Identified in Extant Birds
Examples of moult strategies in living birds. Marbled godwit (Limosa fedoa) in (A) showing a gradual sequential moult. The flightless cormorant (Nannopterum harrisi) during a non-sequential moult with both wings showing old, new and growing feathers without any order or symmetry. A common loon (Gavia immer) after simultaneous shedding of all the wing’s feathers as part of a non-sequential simultaneous moult. An African darter (Anhinga rufa) in (D) that is characterised by a non-sequential moult in which its flight feathers grow simultaneously.
Picture credit: Kiat et al plus Gartner, Salmond, S. P. d’Entremont, Francey (Journal of Current Biology)
Moulting Strategies
In total, the moulting strategies of 302 living bird species were studied, including active fliers and ground-dwelling birds incapable of powered flight. These findings were than applied to the feather arrangement, composition and morphology as found in the wing of the Microraptor gui holotype specimen. The researchers were unable to distinguish between simultaneous and irregular moulting (strategy 2 and 3), so they confined their study to a direct comparison between sequential moulting (strategy 1) and non-sequential moulting (strategies 2 and 3).
The moulting strategy adopted by a bird species impacts on their ability to fly and provides clues about their habitat.
For example, those birds that spend much of their time in the air or live in habitats which are open with few hiding places to help them avoid predators, sequential moulting tends to be adopted. This ensures that the birds can still fly even during moulting. Birds that do not fly frequently, or that have access to plenty of hiding places in their habitat so that they can avoid detection by predators tend to shed a large number of feathers simultaneously and have a relatively rapid moult, typically no more than 2-3 weeks, but if they are a volant species their ability to fly is severely impeded during this time.
The Implications for Microraptor gui
A detailed examination of the wing feathers preserved on the holotype specimen of Microraptor led the researchers to identify six feathers of differing sizes (a-g in the diagram below). These feather lengths were in a sequence indicating that Microraptor moulted gradually and sequentially.
Evidence of Sequential Moulting in Microraptor (M. gui)
The holotype specimen exhibits an active moult in the primaries (the arrow points to the moult-related wing gap). The bottom right inset shows how the researchers identified seven primaries in the specimen’s wing, marked as P(a)–P(g).
Picture credit: Kiat et al (Journal of Current Biology)
This suggests that Microraptor probably spent a considerable portion of each day in the air and that it needed to be able to fly to avoid predators and to forage for food. Furthermore, Microraptor required this capability on a daily basis, including during the moulting process.
Wing Moult (Sequential Shedding) in Microraptor
Illustration (A) shows fully grown primary feathers on the wing, whilst (B), shows light grey feathers which have yet to be shed.
Picture credit: Kiat et al (Journal of Current Biology) with additional annotation by Everything Dinosaur
Microraptor gui Demonstrating Sequential Moulting
Microraptor is the earliest known feathered vertebrate to demonstrate sequential moulting and this suggests that this strategy is nested very deep within the Maniraptora lineage that led to the evolution of birds. It likely maintained its flight ability throughout the entire year. These findings support the hypothesis that Microraptor was a strong, capable flier. The researchers conclude that flight was essential for either its daily foraging or escaping from predators and that sequential moulting is the outcome of evolutionary pressures to maintain flight capability throughout the entire annual cycle in both extant birds and non-avialan paravian dinosaurs from 120 million years ago.
Microraptor Probably Sequentially Moulted Which Infers it was a Strong Flier
Showing the iridescent feathers and the bifurcated tailfan of the CollectA Deluxe Microraptor model. New study of the Microraptor gui holotype suggests sequential moulting and from this it is inferred that flight was essential for either Microraptor’s daily foraging or to avoid predators. Picture credit: Everything Dinosaur.
Picture credit: Everything Dinosaur
The picture (above) shows a CollectA Deluxe Microraptor model.
The scientific paper: “Sequential Molt in a Feathered Dinosaur and Implications for Early Paravian Ecology and Locomotion” by Yosef Kiat, Amir Balaban, Nir Sapir, Jingmai Kathleen O’Connor, Min Wang and Xing Xu published in the journal Current Biology.
Comprehensive Review of Dilophosaurus – Paints New Picture of Predator
Researchers from the University of Texas at Austin and the Petrified Forest National Park have published a comprehensive review of Dilophosaurus wetherilli fossil material and revealed that “double-crested lizard” had stronger jaws than previously thought. Those famous skull crests turn out to be more robust as well. Instead of being regarded as a delicately-jawed scavenger, this iconic dinosaur from the Early Jurassic of North America may have been an apex predator.
Previously Thought to be Quite Lightly Built with Delicate Jaws
Wild Safari Dinosaurs compared. Dilophosaurus had been thought to be much more lightly built than other Jurassic theropods. However, a comprehensive review of fossil material suggests that our perceptions regarding Dilophosaurus may have to change.Picture credit: Everything Dinosaur.
Picture credit: Everything Dinosaur
Not a Member of the Ceratosauria Clade?
Writing in the “Journal of Palaeontology”, researchers Adam Marsh (University of Texas Austin) and Timothy Rowe (Division of Resource Management, Petrified Forest National Park, Arizona), conducted an extensive review and re-examination of all the know specimens of Dilophosaurus wetherilli and concluded that this large-bodied theropod was probably not a member of the Ceratosauria or indeed, the Coelophysoidea, but was a stem-averostran theropod, a member of the Averostra clade. As such, D. wetherilli shows a phylogenetic relationship with Cryolophosaurus ellioti which is known from the Early Jurassic of Antarctica and Zupaysaurus rougieri, fossils of which come from the Late Triassic of Argentina.
The Review Included A Reassessment of the Holotype Skull Material
Dilophosaurus wetherilli holotype specimen (UCMP 37302): (1–4) articulated right side of the skull and line drawings. Plus (5, 6) nasolacrimal crest, (7, 8) left postorbital, (9, 10) left lacrimal, (11, 12) left quadratojugal, and (13, 14) left squamosal in (1, 2, 5, 7, 9, 11, 13) lateral and (3, 4, 6, 8, 10, 12, 14) medial view.
Picture credit: Marsh et al (Journal of Palaeontology)
Dilophosaurus wetherilli
With an estimated body length of around six metres, D. wetherilli is one of the largest terrestrial predators known from the Early Jurassic of North America. Despite extensive study of the fossil material and this dinosaur’s on-going popularity with the public due to its depiction as a venom-spitting, frilled dinosaur in the first “Jurassic Park” film released in 1993, much of the animal’s skeleton, anatomy, ontogeny and taxonomic relationship with other members of the Theropoda remains unknown.
Using fossils collected from the middle and lower portions of the Kayenta Formation (Navajo Nation, northern Arizona), the scientists comprehensively reviewed the holotype cranial material (UCMP 37302). In addition, previously undescribed specimens were analysed and it was concluded that the fossils represent a single species, a large, crested theropod within the Kayenta Formation. This suggests that Dilophosaurus, as a species, persisted for a long time – several million years.
Dilophosaurus Fossil Finds in the Navajo Nation
Localities from which Dilophosaurus wetherilli (Welles, Reference Welles 1954) has been collected in northern Arizona. The shaded region in the north-eastern corner of the state represents the Navajo Nation. The inset stratigraphic column idealizes the section near Tuba City and Gold Spring, Arizona. The dark green unit underlying the Kayenta Formation represents the Moenave Formation and the Wingate Sandstone in the western and eastern half of the Navajo Nation, respectively. Outcrop area modified from Cooley et al (1969).
Picture credit: Marsh et al (Journal of Palaeontology)
It is noted that many anatomical characteristics of the skeleton are more derived when compared to Late Triassic theropods, adaptations to a larger body size and a more robust macropredatory habit.
An Articulated Hindlimb Assigned to D. wetherilli
Dilophosaurus wetherilli referred specimen (TMM 43646-1): articulated right hindlimb.
Picture credit: Marsh et al (Journal of Palaeontology)
Dilophosaurus an Apex Predator
Previous research had suggested that Dilophosaurus had weak jaws and this may have influenced how this dinosaur was depicted in the “Jurassic Park” franchise. This review identified areas of attachment for powerful jaw muscles and that the skeleton was pneumatised (air pockets) and these structures would have helped to both lighten and strengthen the skull. The authors state that whilst Dilophosaurus could catch small animals and even catch fish in the fluvial environment with which its fossils are associated, the robust upper jaw and strong grasping hands suggest that it was equipped to tackle far larger prey.
The idea of Dilophosaurus being a much more powerful and dangerous animal is supported by the discovery of partially articulated specimens of the early sauropodomorph Sarahsaurus (S. aurifontanalis) containing large bite marks alongside shed teeth and a skeleton of Dilophosaurus wetherilli within the same quarry as reported by Rowe et al in 2011.
A Dilophosaurus Braincase
During the comprehensive review, the researchers were able to assign to the Dilophosaurus genus a number of other specimens that had come from the Kayenta Formation, including a remarkably-well preserved small braincase from a juvenile.
Commenting on their fortuitous find Dr Marsh stated:
“In the midst of the analysis, we discovered that a small braincase in the Jackson School’s collections belonged to a Dilophosaurus wetherilli. We realised that it wasn’t a new type of dinosaur, but a juvenile Dilophosaurus wetherilli, which is really cool.”
The More Robust Rebor Figures Introduced in 2019 May Represent a More Accurate Depiction of Dilophosaurus wetherilli
The Rebor Dilophosaurus replicas “Green Day” and “Oasis”. A new study suggests that the jaws and bony crests of Dilophosaurus wetherilli were more robust than previously thought.
Picture credit: Everything Dinosaur
The picture (above) shows the Rebor Dilophosaurus figures.
The strong jaws coupled with the powerful forelimbs suggests that Dilophosaurus was an active predator rather than a scavenger. It seems that many palaeontologists perceptions regarding Dilophosaurus wetherilli will have to be reconsidered, science as well as the film industry might have got this dinosaur all wrong.
The scientific paper: “A comprehensive anatomical and phylogenetic evaluation of Dilophosaurus wetherilli (Dinosauria, Theropoda) with descriptions of new specimens from the Kayenta Formation of northern Arizona” by Adam D. Marsh and Timothy B. Rowe published in the Journal of Palaeontology.
Irisosaurus yimenensis – New Species of “Core Prosauropod” from Southern China
Researchers writing in the open access journal Scientific Reports have described a new species of Early Jurassic herbivorous dinosaur from China. The animal, named Irisosaurus yimenensis is known from fragmentary remains and demonstrates a suite of unusual anatomical features that suggests this genus is a member of the Sauropodiformes, between early-branching “core prosauropods” and the late-branching “sauropod-like” members of the non sauropodan sauropodomorphs. The fossilised remains come from the Fengjiahe Formation close to the village of Zhanmatian in Yunnan province.
A Life Reconstruction of Irisosaurus yimenensis
Irisosaurus yimenensis life reconstruction. This herbivorous dinosaur is thought to have been bipedal, measuring approximately 5 metres in length and from the Early Jurassic of China (Pliensbachian faunal stage of the Early Jurassic).
Picture credit: Ang Li
Fossil Material Found in 2018
The researchers which include Claire Peyre de Fabrègues of Yunnan University analysed the partial skeleton and concluded that Irisosaurus has a body plan close to that of the so-called “core prosauropods” in having, for instance, cervical vertebrae longer than most dorsal vertebrae, gracile forelimbs which are much shorter than the hindlimbs, a deltopectoral crest extending half of the total length of the humerus and a unique carpal-metacarpal complex. The fossil material has been dated to approximately 185 million years ago (Pliensbachian faunal stage of the Early Jurassic), it was discovered in 2018. A phylogenetic analysis confirmed that Irisosaurus belongs to non-sauropodan sauropodomorphs and places it as the sister taxon to Mussasaurus which lived more than thirty million years early in Argentina.
Phylogenetic Analysis places Irisosaurus as the Sister Taxon to the South American Mussaurus
Phylogenetic analysis places Irisosaurus as the sister taxon to the South American Mussaurus
Picture credit: Scientific Reports
On the Road to the Sauropoda
The Sauropodomorpha is defined as saurischian dinosaurs that incorporate the Sauropoda and the early diverging sauropodomorphs. The earliest sauropodomorphs are known from the Late Triassic, with most of the described species from Gondwana. The Laurasian record of these types of dinosaurs does consist of some Triassic forms, but the majority of the known species date from the Jurassic. Among the fourteen Jurassic non-sauropodan sauropodomorphs from Laurasia described to date, eight are from China. Nearly all of the non-sauropodan sauropodomorph genera currently known from China were first reported from the Lufeng Formation, which is also associated with the Yunnan province. The Fengjiahe Formation is the southern equivalent of the Lufeng Formation, it has revealed a similar ancient dinosaur dominated biota.
Silhouette of Irisosaurus yimenensis with Some of the Fossil Material
Silhouette of Irisosaurus yimenensis with some of the fossil material. The most informative elements are figured; (a) Outline; (b) Tooth; (c) Left maxilla; (d) Middle cervical; (e) Posterior cervical; (f) Anterior dorsal; (g) Middle dorsal neural spine; (h) Right scapula; (i) Right humerus; (j) Right ulna; (k) Right manus. Scale bars = 1 m (a);1 cm (b); 5 cm (c–g); 10 cm (h–k).
Picture credit: Scientific Reports
What’s in a Name (Etymology)?
The generic name refers to the famous iridescent clouds of Yunnan Province (彩云之南). The specific epithet refers to Yimen County, where the type locality is located
The scientific paper: “A new species of early-diverging Sauropodiformes from the Lower Jurassic Fengjiahe Formation of Yunnan Province, China” by Claire Peyre de Fabrègues, Shundong Bi, Hongqing Li, Gang Li, Lei Yang and Xing Xu published in Scientific Reports.
Scientific Paper on Oculudentavis khaungraae Retracted
On March the 11th (2020), a scientific paper was published in the academic journal “Nature” highlighting another remarkable discovery found in an amber nodule from northern Myanmar. The Cretaceous-aged amber had already provided some astonishing information on the forest biota close to a coastline from around 100 million years ago.
An ammonite shell entombed in the ancient tree resin for example, then there was the remains of a tiny baby snake (Xiaophis myanmarensis), fossilised frogs and a whole range of insects, plant and pollen fossils, not to mention preserved remains of enantiornithine birds and a partial feathered tail from a dinosaur. Everything Dinosaur had covered these discoveries within this blog, but this new paper, written by Xing et al concerned something truly breath-taking… the title of the paper summed it up nicely – “Hummingbird-sized dinosaur from the Cretaceous period of Myanmar”.
A Tiny Fossilised Skull – The Skull of a Maniraptoran?
Tiny fossil skull preserved in amber (Oculudentavis khaungraae).
Picture credit: Lida Xing et al
Something Tiny But Very Big
The research team, comprised of scientists from the China University of Geosciences, the Natural History Museum of Los Angeles County (USA), the Royal Saskatchewan Museum (Canada) and the Chinese Academy of Sciences, described an amazingly well-preserved tiny fossil skull with very bird-like features but miniscule teeth present in its jaws. The tiny specimen, less than 1.5 cm long was thought to represent the smallest dinosaur known to science. The animal was named Oculudentavis khaungraae, the genus name means “eye tooth bird” in recognition of its enormous eyes and unusual characteristic of having some of the upper teeth located directly under the eye socket.
Computer Generated Image of the Bird-like Skull (O. khaungraae)
Oculudentavis khaungraae computer generated image of the skull (left lateral view). The genus name translates as “eye tooth bird”, whilst the trivial name honours the person who donated the amber nodule to a museum (Hupoge Amber Museum).
Picture credit: Xing et al (Nature)
Oculudentavis khaungraae was documented as representing the smallest dinosaur and compared to the smallest extant avian dinosaur Mellisuga helenae, the bee hummingbird.
However, in what we at Everything Dinosaur think is an unprecedented development, the scientific paper announcing this amazing discovery has, this week, been retracted.
A statement on the “Nature” website reads:
“We, the authors, are retracting this Article [the March 11th paper] to prevent inaccurate information from remaining in the literature. Although the description of Oculudentavis khaungraae remains accurate, a new unpublished specimen casts doubts upon our hypothesis regarding the phylogenetic position of HPG-15-3.
The specimen number HPG-15-3, is the holotype cranial material currently in the collection of the Hupoge Amber Museum in China.
A Controversial Scientific Paper
Shortly after the scientific paper’s publication, a number of academics challenged the conclusions drawn and criticised the authors for their taxonomic assessment which relates to Oculudentavis khaungraae being classified as “bird-like” and placed within the Avialae, a clade that includes elements of the Maniraptora (some theropod dinosaurs and birds).
It was suggested that the phylogenetic assessment carried out was too biased towards resolving the placement of Oculudentavis as a bird or a very closely related dinosaur, rather than considering other data sets that might resolve its position elsewhere. The “bird-like” skull is found in a number of lizards (examples of convergent evolution), several authors commented that the possibility of O. khaungraae being a lizard was discounted too quickly by the paper’s authors.
Everything Dinosaur reported these concerns and doubts in a follow up article to the original post about the scientific paper on March 15th (2020): Casting Doubt over Oculudentavis.
Can a Binomial Name be Obliterated?
It is rare for a scientific paper to be retracted, but occasionally this happens. Papers can be retracted for any of a number of reasons, but normally a retraction occurs when serious questions surrounding its veracity are identified. For example, a paper published in 1998 in the medical journal the “Lancet” by Wakefield et al reporting a link between the MMR vaccination and autism was retracted in 2012 following an extensive investigation. The British Medical Journal (BMJ), put out a press release stating that following the investigation it had been concluded that the paper implying a link between the MMR jab and autism was an “an elaborate fraud.”
Dr Fiona Godlee, BMJ Editor in Chief stated at the time:
“The MMR scare was based not on bad science but on a deliberate fraud” and that such “clear evidence of falsification of data should now close the door on this damaging vaccine scare.”
The scientific binomial name Oculudentavis khaungraae is now in limbo. It is a matter of record that the taxon name exists, but with the withdrawal of the paper, we at Everything Dinosaur are not sure what will happen. It probably falls within the remit of the International Commission on Zoological Nomenclature (ICZN), to produce a ruling on how to treat this taxon.
This development does not undermine the astonishing fossil discoveries being made as researchers study amber from Myanmar, it might help to bring into focus some of the ethical issues associated with the commercial mining and use of funds, but scientific reporting is essentially built on trust. Fossils have been frequently misidentified , as new evidence emerges so ideas, theories and hypotheses evolve and develop. Normally, scientists correct their findings in subsequent papers, to have a scientific paper retracted is highly unusual.
Oculudentavis khaungraae – A Taxon in Limbo
The validity of the taxon is in limbo after scientific paper was retracted.
Picture credit: Han Zhixin with additional annotation by Everything Dinosaur
Schleitheimia schutzi – Oldest Known Transitional Sauropodomorph
The biggest dinosaurs of all were the sauropods. Famous giants such as Diplodocus and Brachiosaurus, exhibits of which adorn numerous main galleries of natural history museums around the world. However, how these giant quadrupeds evolved from their much smaller sauropodomorph ancestors is poorly understood. A team of scientists from Munich, Utrecht and Zürich have been able to identify a new ancestor of the long-necked dinosaurs (true Sauropoda), from strata in the Swiss Canton of Schaffhausen. The dinosaur named Schleitheimia schutzi is the oldest transitional form between the Sauropodomorpha and the Sauropoda described to date.
A Life Reconstruction of Schleitheimia schutzi
An illustration of the giant, newly described Sauropodomorpha Schleitheimia schutzi. A Plateosaurus is in the background and a predatory pseudosuchian can be seen in the foreground.
Picture credit: Beat Scheffold (Naturforschende Gesellschaft Schaffhausen)
Hidden Amongst the Substantial Plateosaurus Remains
Although there are several substantial bonebeds in Switzerland that represent the Plateosaurus genus, (a sauropodomorph) and our knowledge regarding the global distribution of this group has certainly improved over the last five years or so, the diversity of the Sauropodomorpha and its composition remains controversial.
The researchers which include Professor Oliver Rauhut from the Bayerische Staatssammlung für Paläontologie und Geologie, (Munich), Femke Holwerda currently at the Royal Tyrrell Museum (Alberta, Canada) and Heinz Furrer from Zürich University re-examined a series of fragmentary fossils recovered from three different locations associated with Plateosaurus bonebeds. They concluded that the material represents the remains of two different, very big and robust sauropodomorphs. One of these is described as a new taxon – Schleitheimia schutzi.
A Partial Femur Assigned to Schleitheimia schutzi
Distal end of left humerus of Schleitheimia schutzi n. gen., n. sp., PIMUZ A/III 549. a anterior view; b lateral view; c posterior view; d medial view; e distal view; f, proximal view of proximal break. Scale bar = 5 cm.
Picture credit: Rauhut et al (Swiss Journal of Geosciences)
The fossils had been thought to represent large examples of Plateosaurus. Some of the material had been collected decades ago and given the huge size of the bonebeds and their monodominant nature little further thought had been given to the over-sized bones associated with the sites.
Identifying Schleitheimia schutzi
Professor Rauhut explained:
“Although Schleitheimia schutzi probably looked quite similar to Plateosaurus, this dinosaur with an estimated 9 to 10 metres body length is already significantly larger than the latter. The new species [S. schutzi] was apparently very robust and like its gigantic descendants, probably moved on all fours, while Plateosaurus mostly walked on its hind legs.”
The genus name honours the type locality at Schleitheim, Canton Schaffhausen, Switzerland, whilst the species name honours Emil Schutz (1916-1974) who collected the type material.
Special in Two Ways
Schleitheimia roamed central Europe around 210 million years ago (late Norian faunal stage of the Triassic). This makes Schleitheimia a lot older than other known transitional types of dinosaur between sauropodomorphs and sauropods. Secondly, it is the first transitional form known from the continent of Europe. Phylogenetic assessment suggests that this dinosaur is a derived basal sauropodiform and possibly very close to the evolutionary line that led to the Sauropoda. Its discovery highlights the diversity of sauropodomorphs in the Late Triassic and suggests that many types of sauropodomorph survived the end-Triassic extinction event and flourished in the early Jurassic.
Views of a Cervical Vertebra (Schleitheimia schutzi)
Posterior cervical vertebra of Schleitheimia schutzi n. gen., n. sp., PIMUZ A/III 538. a, b left and right lateral views; c dorsal view; d anterior view; e posterior view; f ventral view. Scale bar = 5 cm.
Picture credit: Rauhut et al (Swiss Journal of Geosciences)
The scientific paper: “A derived sauropodiform dinosaur and other sauropodomorph material from the Late Triassic of Canton Schaffhausen, Switzerland” by Oliver W. M. Rauhut, Femke M. Holwerda and Heinz Furrer published in the Swiss Journal of Geosciences.
Well-preserved Skeleton Provides Information on Evolution of Toothed Whales
The well-preserved fossilised remains of a large cetacean from the coastal low country of South Carolina is helping palaeontologists to better understand the evolution of rapid locomotion in toothed whales. The specimen, which is nearly complete (cranial material, plus most of the spine and the remains of one flipper), was found in the early 1990s by Mark Havenstein, a commercial palaeontologist and a former student at the College of Charleston in South Carolina. The skeleton was later acquired by a private fossil collector before being donated to the Mace Brown Museum of Natural History at the College.
Dangerous Prehistoric Dolphin
Writing in the academic journal “Current Biology”, a team of researchers led by Robert W. Boessenecker (Department of Geology and Environmental Geosciences, College of Charleston), have identified it as a large, predatory dolphin which shows adaptations within its skeleton to permit fast swimming.
Palaeontologist Robert W. Boessenecker Poses with the Fossil Material
Robert W. Boessenecker (Department of Geology and Environmental Geosciences, College of Charleston), poses with the Ankylorhiza prehistoric dolphin fossil material.
Picture credit: College of Charleston/Robert Boessenecker
Extant cetaceans are superbly adapted to a marine existence, with tail flukes a key evolutionary innovation in propulsion, an adaptation shared by all living species. Some dolphins, for example, have been recorded swimming at speeds in excess of 50 km/h (27 knots). These fast speeds and bursts of acceleration are attributed to the thrust provided by the powerful tail fluke with flippers providing steering. These movements are enabled by a sturdy and powerful body with a relatively rigid torso consisting of numerous compacted vertebrae and movement in the water is adjusted by varying the angle of the flippers.
The Rarity of Oligocene Cetacean Skeletons
Eocene-aged cetaceans reveal a transition from a semi-aquatic lifestyle to a fully aquatic one with adaptations to permit a nektonic habit. However, the rarity of Oligocene whale skeletons has hampered the efforts of palaeontologists to understand how the evolution of tail fluke-powered, but forelimb-controlled locomotion came about. The newly named Ankylorhiza tiedemani, which had previously only been known from a partial rostrum, represents a transitional form in terms of its forelimb shape and structure. Its forelimb is intermediate in morphology between stem cetaceans and living whales, whereas its axial skeleton displays incipient rigidity at the base of the tail with a flexible lumbar region.
Ankylorhiza tiedemani Probably Occupied an Apex Predator Niche
A pod of the dangerous prehistoric dolphin Ankylorhiza tiedemani attacking seabirds.
Picture credit: Robert Boessenecker
Commenting on the importance of the South Carolina specimen, lead author Robert Boessenecker explained that the discovery was one of the first skeletons found of a very early member of the toothed whales (Odontoceti), shortly after they diverged around 35-36 million years ago from baleen whales (Mysticeti).
He added:
“What makes that important is its evolutionary position as a very early branching dolphin. Most early dolphins are known only from skulls, so having a skeleton with flippers and most of the vertebrae gives us an unprecedented look into the evolution of swimming adaptations. That unprecedented window surprisingly told us that baleen whales and dolphins have many similarities owing to convergent evolution since their evolutionary split 35 million years ago.”
“Fused Roots”
The scientists estimate that Ankylorhiza grew to about 4.8 metres in length and probably occupied a similar predatory role in marine environments as modern orcas do today. The genus name means “fused roots” and refers to the strongly fused tooth roots.
A phylogenetic assessment places Ankylorhiza near to the base of the toothed whale radiation and if this is the case, than it implies that several adaptations to aid locomotion such as a shortened humerus and a narrow but powerful peduncle (the end of the body that is adjacent to the fluke), evolved independently in both the Odontoceti and the Mysticeti. In essence, that there is evidence to support the theory of convergent evolution in locomotor features between toothed and baleen whales.
The Fossil Material and a Skeletal Outline of Ankylorhiza tiedemani
Ankylorhiza fossils and skeletal outline. Items in white are known fossils.The fossilised remains of a prehistoric dolphin.
Picture credit: Boessenecker et al (Current Biology)
A Prehistoric Dolphin with Primitive and Derived Characteristics
Ankylorhiza’s skeleton shows a combination of more derived as well as primitive features, thus helping to cement it as a basal member of the toothed whale lineage.
Robert Boessenecker stated:
“These primitive features are surprising because palaeontologists and biologists long assumed that many of the adaptations for rapid swimming in baleen whales and toothed whales were ancient adaptations shared thanks to their common heritage over the past 35 million years.”
Everything Dinosaur acknowledges the assistance of a press article from the College of Charleston in the compilation of this article.
The scientific paper: “Convergent Evolution of Swimming Adaptations in Modern Whales Revealed by a Large Macrophagous Dolphin from the Oligocene of South Carolina” by Robert W. Boessenecker, Morgan Churchill, Emily A. Buchholtz, Brian L. Beatty and Jonathan H. Geisler published in Current Biology.
