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Fossil finds, new dinosaur discoveries, news and views from the world of palaeontology and other Earth sciences.

28 07, 2020

“Captain Hook” Dinosaur from Hell Creek

By | July 28th, 2020|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

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

Life reconstruction Trierarchuncus 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)

Three claws ascribed to the genus Trierarchuncus.

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

The three alvarezsaurid thumb claws showing a possible growth sequence.

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)

Trierarchuncus prairiensis thumb claw showing curvature.

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.

Evidence suggests that alvarezsaurids originated in Asia: Haplocheirus – Is it a bird?  No, it is a dinosaur.

Did alvarezsaurids eat eggs?  An article from 2018: Did Alvarezsaurids eat eggs?

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.

27 07, 2020

Microraptor Moulted Just Like Many Modern Birds

By | July 27th, 2020|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

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 (M. 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

Microraptor fossil.

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

Different strategies of feather moulting in living 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.  The 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)

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.

Implications for Microraptor

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)

Sequential moulting in Microraptor.

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

Wing moult 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 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.  Microraptor 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

The CollectA Deluxe Microraptor Model.

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

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.

25 07, 2020

Beefing Up Dilophosaurus

By | July 25th, 2020|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

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

Comparing Wild Safari dinosaur models.

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

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 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

Dilophosaurus fossil finds (location and stratigraphcial map).

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 articulated right hindlimb.

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

Rebor Dilophosaurus models "Green Day" and "Oasis"

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 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.

24 07, 2020

Irisosaurus yimenensis – New Species of “Core Prosauropod”

By | July 24th, 2020|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles|0 Comments

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 illustration.

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

Irisosaurus phylogeny.

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

Irisosaurus yimenensis outline and 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.

23 07, 2020

Scientific Paper on Hummingbird-sized Dinosaur Retracted

By | July 23rd, 2020|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

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?

Oculudentavis khaungraae skull in amber.

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.

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

Oculudentavis - is this an invalidated taxon?

The validity of the taxon is in limbo after scientific paper was retracted.

Picture Credit: Han Zhixin with additional annotation by Everything Dinosaur

We shall await developments…

17 07, 2020

Schleitheimia Fills a Sauropod-sized Gap in Dinosaur Evolution

By | July 17th, 2020|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

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

Schleitheimia schutzi life reconstruction.

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

Partial femur assigned to Schleitheimia.

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.

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)

Neck bones (cervical vertebrae) attributed to Schleithimia.

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.

15 07, 2020

Deadly Dolphin Predator of the Oligocene Epoch

By | July 15th, 2020|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

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 1990’s 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.

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

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 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.  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

Ankylorhiza tiedemani life reconstruction.

A pod of Ankylorhiza tiedemani prehistoric dolphins 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 fossil material.

Ankylorhiza fossils and skeletal outline.  Items in white are known fossils.

Picture Credit: Boessenecker et al (Current Biology)

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.

13 07, 2020

Lusovenator santosi – A Carcharodontosaur from the Upper Jurassic of Portugal

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The “Hunter of Lusitania” – Lusovenator santosi

The fearsome carcharodontosaurids (family Carcharodontosauridae), comprise some of the largest terrestrial predators that ever lived.  Giant theropods such as Giganotosaurus, Carcharodontosaurus and Tyrannotitan rivalled the largest tyrannosaurs in terms of size and probably (in some cases), were even bigger.  It had been thought that these types of carnivorous dinosaur were confined to the Cretaceous, but there is a growing body of evidence to suggest that this group was well established and geographically widespread by the Late Jurassic.

A team of scientists writing in the “Journal of Vertebrate Paleontology” have described a new species of carcharodontosaurid based on fossils found in Portugal.  The dinosaur has been named Lusovenator santosi, the genus name translates as “hunter of Lusitania”, a reference to the Lusitanian Basin, the geological region where the fossils are from.  Their research supports the idea that these types of predators were present in the northern hemisphere some twenty million years earlier than previously thought.

A Life Reconstruction of the Late Jurassic Carcharodontosaurid Lusovenator santosi

Lusovenator life reconstruction.

A life reconstruction of Lusovenator.

Picture Credit: Carlos de Miguel Chaves

A Reassessment of Allosaur Fossil Material

The researchers, based in Lisbon and Madrid, re-evaluated fragmentary fossil material collected over the last two decades at sites located on the Portuguese coast about 35 miles (60 kilometres), north of Lisbon.  Initial examination suggested that this material represented a member of the Allosauridae, but a more detailed analysis of the fossils led the researchers to conclude that this material represented a dinosaur from the Carcharodontosauridae, a family nested within the clade Allosauria, but distinct from famous Late Jurassic super-predators such as Allosaurus fragilis, which is known from the western United States.

Lead author of the scientific paper, Elisabete Malafaia (University of Lisbon), commented that this discovery demonstrates the importance of the Iberian Peninsula as a key region for understanding the dispersal of carcharodontosaurids as well as other types of dinosaur across the northern hemisphere during the Late Jurassic and Early Cretaceous.

Fossil Material Assigned to Lusovenator santosi

Lusovenator fossil material.

Fossil material assigned to Lusovenator santosi with a silhouette showing skeletal location.

Picture Credit: Malafaia et al (Journal of Vertebrate Palaeontology)

One of the Oldest Members of the Carcharodontosauridae

The oldest definitive carcharodontosaurid described to date is Veterupristisaurus (V. milneri) from the Middle Dinosaur Member of the famous Tendaguru Formation of Tanzania.  Veterupristisaurus (pronounced Vet-ter-roo-pris-tee-sore-us), is believed to have lived around 154 million years ago (Kimmeridgian faunal stage of the Late Jurassic).  Other fragmentary fossil remains from China and Germany have also been tentatively assigned to Late Jurassic carcharodontosaurids.  Lusovenator lived around 145 million years ago, as such, it is the oldest carcharodontosaurian allosauroid yet discovered from Laurasia.

The fossil material is believed to represent a relatively young animal, with a body length of approximately 3.5 metres.  Although, probably not fully grown, the vertebrae and the ilium show a number of anatomical traits that distinguish Lusovenator from the Allosauridae and nest it with the related, but distinct Carcharodontosauridae.

A Member of a Field Team Working on a Fossil Specimen

Field work - carefully extracting fossil material.

A field team member working on fossil material.

Picture Credit: LUSA

Furthermore, the identification of this new species expands the diversity of theropod dinosaurs known from the Late Jurassic of Portugal and reinforces the theory that the Iberian Peninsula is a key region to help understand the dispersal of a number of different types of dinosaur across the Northern Hemisphere at the end of the Jurassic and into the Early Cretaceous.

The scientific paper: “A new carcharodontosaurian theropod from the Lusitanian Basin: evidence of allosauroid sympatry in the European Late Jurassic” by Elisabete Malafaia, Pedro Mocho, Fernando Escaso and Francisco Ortega published in the Journal of Vertebrate Paleontology.

10 07, 2020

Aratasaurus museunacionali “Lizard Born of Fire”

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Aratasaurus museunacionali Newly Described Basal Coelurosaur

This month a new basal member of the Coelurosauria has been named and described from limb bones sourced from the Romualdo Formation in north-eastern Brazil.  The dinosaur has been named Aratasaurus museunacionali, the genus name translates as “lizard born of fire” a reference to the fact, the fossil had been in the National Museum of Brazil (Museu Nacional), when a fire ripped through the building.  Fortunately, the fossil material was not damaged and the research could be successfully concluded and a new genus of Early Cretaceous dinosaur described.

Aratasaurus museunacionali Life Reconstruction

Aratasaurus museonacionali illustration.

Aratasaurus museunacionali life reconstruction.

Picture Credit: Museu Nacional

The species name honours the Museu Nacional in recognition of the tragic fire that took place in September 2018.  To read more about the fire: Devastating Fire at Brazil’s National Museum.

Juliana Sayão, a palaeontologist from the Federal University of Pernambuco and lead author of the scientific paper, commented that this new theropod will help scientists to better understand the evolutionary history of the Coelurosauria, an extensive clade of dinosaurs that consists of the tyrannosaurids, compsognathids, the ornithomimosaurs and the Maniraptora which includes birds.  A phylogenetic assessment suggests that Aratasaurus is closely related to Zuolong (Z. salleei), from the Late Jurassic of China, although it lived much more recently, the sediments from which the limb elements were excavated have been dated to approximately 110-115 million years ago (Albian faunal stage of the Cretaceous).

The Right Pes of Aratasaurus museunacionali after Preparation

Fossils associated with Aratasaurus museonacionali.

Aratasaurus museunacionali fossils.  The fossils although fragmentary and fragile were preserved in a partially articulated state.

Picture Credit: Museu Nacional

Evidence of Seasonal Fires

The genus name might reflect the ordeal of the fire at the Museu Nacional but tiny pieces of fossilised wood found in association with the dinosaur bones suggest that Aratasaurus had to contend with forest fires within its ecosystem when it roamed this part of Gondwana more than 100 million years ago.

Highlighting the significance of this fossil discovery Juliana Sayão commented:

“Every discovery of a fossil is important because we obtain records that help to reconstruct the history of the planet and remake the path of evolution of the organisms that lived here millions of years ago.  Many times the fossil is unique and provides all the information about that species or group of animals”.

A model of the Brazil’s newest carnivorous dinosaur from the Araripe Basin has been commissioned.  Careful examination of the bone structure (histology), suggests that the individual was approximately four years old when it died.  Based on the growth rates of other, better known coelurosaurs, the researchers propose that the fossils represent a sub-adult specimen.  As such, the size estimate of around three metres in length probably does not represent the maximum size for this dinosaur species.

The Model of Aratasaurus museunacionali

Aratasaurus museonacionali model on display at the museum.

A detailed model of the newly described Aratasaurus museunacionali.

Picture Credit: Museu Nacional

The fossils, consisting of a partial femur, a tibia and foot bones representing an incomplete right limb were discovered in 2008 and first taken to the Museum of Palaeontology Plácido Cidade Nuvens, in Santana do Cariri but transferred to the Laboratory of Paleobiology and Microstructures, at the Academic Centre of Vitória, (Federal University of Pernambuco), for further preparation and study.  As part of the research project, the fossil material was taken in 2016 to the Museu Nacional for further analysis.  Although caught up in the conflagration that destroyed much of the museum in 2018, the specimen survived and the analysis was able to be completed.

Photograph and Line Drawing Showing the Right Pes (Foot)

Fossil and line drawing of Aratasaurus pes.

Part of the holotype material for Aratasaurus with an accompanying line drawing showing metatarsals and pedal digits.  Scale bar equals 5 cm.

Picture Credit: Manso Sayão et al (Scientific Reports)

A spokesperson from Everything Dinosaur commented:

“The specimen might be fragmentary, but it’s discovery underpins the significance of the Romualdo Formation and helps to extend our knowledge of the dinosaur biota inhabiting this part of Gondwana in the later stages of the Early Cretaceous.  As this genus has been classified as the sister taxon of the Chinese Zuolong, it suggests that basal Coelurosaurs may have been more widely distributed and had a greater temporal range than previously thought.”

Everything Dinosaur acknowledges the assistance of a media release from the Museu Nacional in the compilation of this article.

The scientific paper: “The first theropod dinosaur (Coelurosauria, Theropoda) from the base of the Romualdo Formation (Albian), Araripe Basin, Northeast Brazil” by Juliana Manso Sayão, Antônio Álamo Feitosa Saraiva, Arthur Souza Brum, Renan Alfredo Machado Bantim, Rafael Cesar Lima Pedroso de Andrade, Xin Cheng, Flaviana Jorge de Lima, Helder de Paula Silva and Alexander W. A. Kellner published in Scientific Reports.

9 07, 2020

Voracious Xiphactinus was More Widespread than Previously Thought

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The Voracious Xiphactinus was More Widespread than Previously Thought

Xiphactinus (pronounced zee-fak-tin-us), was a fast swimming voracious predator of Cretaceous seas.  With a body length of up to six metres, this bony fish was one of the top predators associated with the Western Interior Seaway of North America.  It has a formidable reputation amongst palaeontologists, as several fossils have been found which show the undigested body parts of prey, preserved inside the stomach cavity.  Perhaps, the most famous specimen that documents predatory behaviour is the Xiphactinus (X. audax), with the complete skeleton of a 1.8 metre-long fish preserved inside its skeleton which is on display at the Sternberg Museum of Natural History (Kansas).

A Bony Fish with a Fearsome Reputation

Xiphactinus with its last meal preserved inside it.

A fossil fish within a fish.  The Xiphactinus audax specimen collected by George F. Sternberg (son of the famous American palaeontologist Charles H. Sternberg).  Inside the body cavity, a nearly complete specimen of the related ichthyodectid Gillicus arcuatus can be seen.

Picture Credit: Everything Dinosaur

A team of scientists have reported this week the first occurrence of Xiphactinus from southern South America.  Writing in the academic journal “Alcheringa”, researchers from the Museo Argentino de Ciencias Naturales “Bernardino Rivadavia” in collaboration with a colleague from Universidad Maimónides, both located in Buenos Aires, report the discovery of fragments of upper jaw bone (maxilla), as well as vertebrae from the Salamanca Formation (Chubut Province, Argentina).  It is estimated that this fish lived around 70 million years ago (Maastrichtian age of the Late Cretaceous).

Xiphactinus Geographically and Temporally Widespread

Xiphactinus has been widely reported from Upper Cretaceous strata throughout the Northern Hemisphere, although to date, equivalent discoveries in the Southern Hemisphere have been limited to a single fossil specimen consisting of elements from the skull and the spine from the Cenomanian aged limestones of the La Aguada Member, La Luna Formation, near Monay, Candelaria Municipality in western Venezuela.

A Life Reconstruction Xiphactinus

Xiphactinus life reconstruction.

A life reconstruction of the fearsome teleost Xiphactinus.

Picture Credit: Everything Dinosaur

This discovery extends the known geographical range for this genus and suggests that this teleost was widespread during the Cretaceous (Albian to Maastrichtian faunal stages).  It is related to the majority of fish species alive today, although the entire family of these types of predatory fish (Ichthyodectidae), became extinct at the end of the Cretaceous.

A Bony Fish with a Formidable Reputation

Xiphactinus attacks.

A bony fish with a very formidable reputation – Xiphactinus audax.

Picture Credit: Everything Dinosaur

The scientific paper: “First record of the ichthyodectiform fish Xiphactinus (Teleostei) from Patagonia, Argentina” by Julieta J. De Pasqua, Federico L. Agnolin and Sergio Bogan published in Alcheringa: An Australasian Journal of Palaeontology.

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