Galleonosaurus dorisae – A New Aussie Dinosaur

A new type of Australian dinosaur has been described from the fossilised remains of five upper jaw bones (maxillae) found at the Flat Rocks locality in the Wonthaggi Formation in the famous Gippsland Basin of Victoria.  Five small-bodied ornithopods are now known from the state of Victoria.  The new plant-eating dinosaur has been named Galleonosaurus dorisae.  The jaw bones are of different sizes and this has permitted palaeontologists to plot growth changes in these little dinosaurs as they matured.

Writing in the Journal of Palaeontology, the researchers which include Matthew Herne (University of New England, New South Wales) and Alistair Evans (Monash University, Melbourne), used detailed CT-scans of the fossil material to gain fresh insights into the structure and morphology of the cranial anatomy and dentition of small Australian ornithopods.  The research leading to the establishment of this new genus has also helped to define more clearly other small ornithopods known from the Gippsland Basin and the Otway Basin located on the opposite side of Port Phillip Bay.

A Life Reconstruction of the Newly Described Ornithopod Galleonosaurus dorisae

Picture credit: James Kuether

Galleonosaurus dorisae – “Galleon Lizard”

When the scientists were examining the maxillae, their shape reminded them of the upturned hull of an old-fashioned sailing ship – a galleon.  It was the morphology of the jaw that inspired the genus name “Galleon Lizard”.  The species or trivial name honours Doris Seegets-Villiers for her geological, palynological, and taphonomic work on the Flat Rocks fossil vertebrate locality.

Jaw Fossils and a Tooth with a CT-scan of the Fossil Material

Picture credit: Herne et al

Niche Partitioning in Ornithopods

The plethora of vertebrate fossils at the Flat Rocks site, suggests that several more dinosaurs await discovery.  However, for the moment, the researchers are confident that Galleonosaurus shared its habitat with at least one other small, light, fast-running ornithopod – Qantassaurus intrepidus.  The jaws of Qantassaurus are more robust and more powerful.  The researchers were able to confirm that Q. intrepidus is uniquely characterised by a deep, foreshortened dentary (lower jaw).  This suggests that the robust Q. intrepidus and the more gracile jawed G. dorisae fed on different vegetation, they did not compete directly for food, an example of niche partitioning.

Dr Herne described Galleonosaurus:

“We know it would have been a two-legged, quite agile plant-eating dinosaur.  It seems that Galleonosaurus was no doubt closely related to possibly as many as four or five other species that look a little bit similar and were similar sizes, but we can tell they’re different by the anatomy of the jaws and the teeth.”

A Lush Conifer Dominated Rift Valley with an Immense Volcanic Mountain Chain to the East

Extensive research on the Otway Formation material to the west of Port Phillip Bay in conjunction with research on the geology of the Gippsland Basin have permitted scientists to build up a picture of what life was like in this part of Australia during the Early Cretaceous.  The dinosaurs lived in an extensive rift valley that had formed as Australia began to separate from Antarctica.

Conifer forests dominated and at such high latitudes, the lush environment would have been subjected to long periods of extensive daylight in the summer, but conversely the winters would have been cold with little daylight each day.  Although the Earth’s climate was much warmer than today during the Early Cretaceous, it is quite possible that these little dinosaurs would have had to endure winter temperatures close to freezing.

Gondwana in the Early Cretaceous (Barremian Faunal Stage)

Picture credit: Herne et al

A Skeletal Reconstruction of the Skull of Galleonosaurus and the Anatomical Position of Jaw Material

Picture credit: Herne et al

A Phylogenetic Analysis of Galleonosaurus dorisae

The scientists conclude that a highly diverse, small-bodied ornithopod fauna flourished in the periodically disturbed, high-latitude, riverine floodplain environment of the Australian-Antarctic rift valley during the Early Cretaceous (Barremian to Early Albian faunal stage).  A phylogenetic analysis places Galleonosaurus as the earliest member of the Elasmaria, a clade of Gondwanan ornithopods distantly related to the Hypsilophodonts.

The Five Victorian Ornithopods – Spanning 12 million years

The Lower Cretaceous rocks either side of Port Phillip Bay were laid down at different times during the Cretaceous.  The Gippsland Basin deposits close to the town of Inverloch, were laid down around 125 million years ago, however, the Otway Basin deposits (Eumeralla Formation), represent younger material laid down in the Early Albian (113 million years ago).

1. Leaellynasaura amicagraphica – named in 1989 (Early Albian faunal stage), from the Eumeralla Formation (Otway Basin).
2. Atlascopcosaurus loadsi – also named in 1989 from the Eumeralla Formation.
3. Diluvicursor pickeringi – named in 2018 (Eumeralla Formation).  To read an article about the discovery of this dinosaur: Fast-running Ornithopod from Victoria.
4. Qantassaurus intrepidus named in 1999 from the Wonthaggi Formation (Gippsland Basin) – older strata associated with the Barremian faunal stage of the Early Cretaceous.
5. The newly described Galleonosaurus dorisae (2019), also from the Wonthaggi Formation.

Dr Herne stated:

“The interesting thing about that whole coast line is it gives us a decent age range over quite a long period.”

A spokesperson from Everything Dinosaur commented:

“It is likely that many more small dinosaurs are going to be named and described in the future.  Fossil finds from Victoria will, most likely, lead to further revisions of Gondwanan ornithopod taxonomy.”

For models and replicas of ornithopods and other dinosaurs: Dinosaur and Prehistoric Animal Models.

The Diminutive Tyrannosaur Moros intrepidus

A small, but speedy dinosaur is the newest member of the Superfamily Tyrannosauroidea, a distant relative of the most famous dinosaur of all Tyrannosaurus rex.  T. rex et al might have a reputation for being giant, bone-crunching apex predators, but for much of their evolutionary history, the tyrannosaurs have been rather over-shadowed by other super-sized dinosaur carnivores.  Indeed, it was only in the last few million years of the Cretaceous that these types of theropod emerged as the apex predators of northern latitudes.  The new dinosaur, named Moros intrepidus, at approximately 78 kilograms (data range 53 to 85 kilograms), around the same bodyweight as a South American Jaguar (Panthera onca), is about ninety times lighter than its famous top-of-the-food-chain relative.

Moros intrepidus

Ironically, contrary to public opinion, M. intrepidus might just be more typical of the Tyrannosauroidea bauplan than its more famous relatives – Gorgosaurus, Albertosaurus and T. rex.

The Newly Described Moros intrepidus from the Late Cretaceous of Central Utah

Picture credit: Jorge Gonzalez

Teeth and a Hind Limb from a New Theropod Dinosaur

The fossilised remains of a partial right leg consisting of a femur, a tibia, metatarsal bones and some toe bones from the fourth toe were discovered in sediments representing the lower Mussentuchit Member of the Cedar Mountain Formation located in Emery County (Utah).  These fossils, in conjunction with isolated teeth from the front portion of the upper jaw (premaxilla) found nearby provide the basis for this new taxon.  The deposits represent a terrestrial environment, a large delta and they date from approximately 96 million years ago (Cenomanian faunal stage of the Late Cretaceous).

Moros intrepidus represents the oldest known Cretaceous-aged tyrannosauroid discovered to date in North America. It extends the definitive fossil record for these types of dinosaurs by around 15 million years.

The Temporal Relationships and Phylogeny of the Tyrannosauroidea

Picture credit: Nature Communications Biology

In the diagram (above), the section on the left (a), shows the fossil record gap between Late Jurassic tyrannosauroids and much larger Late Cretaceous members of the Tyrannosauridae family such as Lythronax (L. argestes).  Section (b) demonstrates the temporal range of these theropods and the change in bauplan, whilst (c) demonstrates key evolutionary anatomical changes.  The blue and pink coloured shapes in (d) reflect the transition from allosaur/megaraptoran dominated ecosystems to tyrannosaur dominated palaeoenvironments.

A Changing of the Guard When it Comes to Apex Predators

Palaeontologists know that the tyrannosaur lineage dates back a long way.  For example, basal tyrannosaurids such as Stokesosaurus (S. clevelandi) are known from Upper Jurassic deposits of Utah.  By the Late Cretaceous (Campanian faunal stage), tyrannosaurs were large and had become the iconic apex predators beloved by dinosaur fans and film directors.  The fossil record for North American tyrannosaurs was essentially blank, giving palaeontologists a T. rex skull-sized headache when it came to piecing together how these theropods changed over time.

The discovery of Moros helps to narrow a 70-million-year-gap in the fossil record of tyrant lizards in North America.

Lead-author of the study, published in “Nature Communications” Lindsay Zanno of the North Carolina Museum of Natural Sciences explained:

“When and how quickly tyrannosaurs went from wallflower to prom king has been vexing palaeontologists for a long time.  The only way to attack this problem was to get out there and find more data on these rare animals.”

A Silhouette of M. intrepidus Showing the Anatomical Position of the Known Fossil Material

Picture credit: Nature Communications Biology

Living in the Shadow of Siats meekerorum

In 2013, two of the authors of the Moros intrepidus paper, Lindsay Zanno and Peter Makovicky (Field Museum, Chicago), published a study on a large allosauroid from similar-aged sediments.  The dinosaur, named Siats meekerorum is estimated to have measured around 12 metres in length, dwarfing the contemporary Moros, which had a hip height of around 1.2 metres.  The researchers conclude that within a palaeoenvironment dominated by giant, allosauroid theropods, tyrannosaurs such as M. intrepidus relied on their speed and small size and would have kept out of the way of the larger predators.

A spokesperson from Everything Dinosaur commented:

“During the Cenomanian, tyrannosauroids like Moros intrepidus were secondary predators within an ecosystem dominated by apex predators from a completely different part of the theropod family tree.  For the greater part of the tyrannosaur evolutionary history, these types of dinosaurs were marginal predators, living in the shadow of much bigger carnivorous dinosaurs.”

A Life Reconstruction of Siats meekerorum with two Tyrannosauroids shown in the Foreground

Picture credit: Julio Laceardo

To read Everything Dinosaur’s article on the discovery of Siats meekerorum: Unravelling the Apex Predators of the Cretaceous Before Tyrannosaurs.

Phylogeny Points at Asian Ancestry

A study of the longer limb bones indicates that the individual was around six to seven years of age when it died.  It was likely to have reached its adult size.  A phylogenetic assessment indicates an affinity with Asian tyrannosaur taxa, in essence, the ancestors of famous North American dinosaurs such as Gorgosaurus and Tyrannosaurus rex migrated into North America from Asia.

Assistant Research Professor Zanno stated:

“T. rex and its famous contemporaries such as Triceratops may be among our most beloved cultural icons, but we owe their existence to their intrepid ancestors who migrated here from Asia at least 30 million years prior.  Moros signals the establishment of the iconic Late Cretaceous ecosystems of North America.”

Views of the Lower Leg Bones from the Right Leg of M. intrepidus

Picture credit: Nature Communications Biology

What’s in a Name?

The etymology of this new tyrannosauroid reflects the later faunal turnover that led to the apex predator roles in North America being dominated by tyrannosaurs.  The genus name is from the Greek “Moros”, the embodiment of impending doom, for the descendants of this fast-running dinosaur were to evolve into some of the largest and most formidable terrestrial predators known to science.  The species name is from the Latin “intrepidus”, a reference to these intrepid dinosaurs making the migration from Asia into North America and their subsequent dispersal.

Size is Not Everything

Although around ninety times lighter than Tyrannosaurus rex, Lindsay warns against underestimating the predatory abilities of Moros.

She added:

“Moros was lightweight and exceptionally fast.  These adaptations, together with advanced sensory capabilities, are the mark of a formidable predator.  It could easily have run down prey, while avoiding confrontation with the top predators of the day.  Although the earliest Cretaceous tyrannosaurs were small, their predatory specialisations meant that they were primed to take advantage of new opportunities when warming temperatures, rising sea-level and shrinking ranges restructured ecosystems at the beginning of the Late Cretaceous.  We now know it took them less than 15 million years to rise to power.”

The scientific paper: “Diminutive fleet-footed tyrannosauroid narrows the 70-million-year gap in the North American fossil record” by Lindsay E. Zanno, Ryan T. Tucker, Aurore Canoville, Haviv M. Avrahami, Terry A. Gates and Peter J. Makovicky published in Nature Communications Biology.

Visit the Everything Dinosaur website: Everything Dinosaur.

Mnyamawamtuka moyowamkia – Heart-shaped Tail Bones Help to Flesh Out Titanosaur Evolution

Scientists writing in the on-line, open access journal PLOS One, have published details of a new species of African titanosaur.  It took several years to carefully remove the fossil material from a high cliff wall overlooking the Mtuka riverbed in south-western Tanzania, but the fossils, representing a not fully mature dinosaur, are providing palaeontologists with important information about how African ecosystems changed over the course of the Cretaceous.  The new titanosaur has been named Mnyamawamtuka moyowamkia (pronounced Mm-nya-ma-wah-mm-too-ka mm-oh-yo-wa-mm-key-ah).  The name is derived from Kiswahili for “animal of the Mtuka river with a heart-shaped tail”.

The heart-shaped tail element of the name refers to the strange shape of the most intact middle caudal vertebra described in the paper.  It bulges out at the sides (dorsolateral expansion of the posterior articular surface of the centrum), a unique tail bone morphology that resembles the shape of a romantic, love heart.

A Life Reconstruction of a Pair of  Mnyamawamtuka moyowamkia Titanosaurs

Picture credit: Mark Witton

Mnyamawamtuka moyowamkia

The first evidence of the dinosaur fossils was noted in 2004 and some fossils were excavated from the cliff face, in what were quite hazardous conditions, with field team members having to be lowered over the cliff on numerous occasions to work on the exposed bones.  Annual excavations took place until 2008, it was important to keep returning to the site as the fossils were in danger of being lost to the river in seasonal floods.

A Line Drawing of the Quarry Site Showing the Extent of the Annual Excavations

Picture credit: PLOS One

Around 110 -100 Million Years Old

The specimen was excavated from the Mtuka Member of the Cretaceous Galula Formation, which was deposited around 110 to 100 million years ago (Aptian to Cenomanian faunal stage of the Cretaceous).  A substantial portion of the postcranial skeleton has been recovered.

Dangerous Work!  The Excavation Site in 2007

Picture credit: Ohio University

Commenting on the importance of this discovery, in relation to the evolution of African titanosaurs, lead author of the paper, Dr Eric Gorscak, a recent PhD graduate of Ohio University and now an assistant professor at the Midwestern University (Illinois), stated:

“Although titanosaurs became one of the most successful dinosaur groups before the infamous mass extinction capping the Age of Dinosaurs, their early evolutionary history remains obscure, and Mnyamawamtuka helps tell those beginnings, especially for their African-side of the story.  The wealth of information from the skeleton indicates it was distantly related to other known African titanosaurs, except for some interesting similarities with another dinosaur, Malawisaurus, from just across the Tanzania–Malawi border.”

Adding to the Diversity of Titanosaurian Sauropods from Africa

The field team responsible for this discovery have also found the fossilised remains of two other titanosaurs in this part of Africa.  In 2017, Everything Dinosaur reported upon the discovery of Shingopana songwensis.

To read about S. songwensis: A New Species of African Titanosaur is Named.

In addition, Rukwatitan bisepultus another Titanosaurian sauropod dinosaur, was named and described in 2014: A New Species of Titanosaurian Sauropod Rukwatitan bisepultus.

The researchers conclude that Mnyamawamtuka moyowamkia was distantly related to both Shingopana songwensis and Rukwatitan bisepultus, fossils of which come from younger Cretaceous sediments, although it did share some anatomical characteristics with Malawisaurus dixeyi from Malawi, that might have been contemporaneous.  This new fossil discovery is helping palaeontologists to better understand the distribution of titanosaurs between Africa and South America and their evolutionary relationships.

Heart-shaped Tail Bones

One of the middle caudal centra (tail bone from the middle portion of the tail), exhibits a unique dorsolateral expansion of the posterior articular surface of the centrum.  This unique characteristic was found to be present in the most intact middle caudal vertebra described.  This unique shape inspired the dinosaur’s name.

Heart-shaped Tail Bone Centrum (Rear View)

Picture credit: PLOS One

Tail Bones of Different Titanosaurs Compared

Picture credit: PLOS One

The scientific paper: “A New African Titanosaurian Sauropod Dinosaur from the Middle Cretaceous Galula Formation (Mtuka Member), Rukwa Rift Basin, Southwestern Tanzania” by Eric Gorscak and Patrick M. O’Connor published in PLOS One.

Visit the Everything Dinosaur website: Everything Dinosaur.

Gobiraptor minutus – The Diversity of the Oviraptoridae in the Late Cretaceous

A new species of oviraptorid dinosaur (Oviraptoridae family), has been described by an international team of scientists.  The little dinosaur was probably feathered and it possessed thickened jaws, an adaptation to feeding on hard food items such as seeds, nuts or the shells of bivalves, molluscs and crabs.  Animals that have a diet of hard items are referred to as durophagous.   

The fossilised remains of a single, very young individual were found in the Altan Uul area of Ömnögovi Province, Mongolia, in strata from the famous Upper Cretaceous Nemegt Formation.  The new species has been named Gobiraptor minutus and it helps to demonstrate that this part of Asia in the Late Cretaceous was home to diverse variety of oviraptorids, many of which, probably occupied specialist niches within the ecosystem in a bid to minimise competition for resources.

A Life Reconstruction of Gobiraptor minutus

Picture credit: Do Yoon Kim with additional annotation by Everything Dinosaur

Gobiraptor minutus – Rare for the Altan Uul Area of Southern Mongolia

Oviraptorid fossil specimens are relatively rare in the Altan Uul area of the Gobi Desert, however, within the Upper Cretaceous deposits exposed within the Gobi Desert, some ten oviraptorid taxa have so far been named and described.  Gobiraptor increases the diversity of oviraptorids known from the Nemegt Formation and demonstrates that these types of theropod dinosaurs were exceptionally abundant in the mesic environment* of that part of the world during the Late Cretaceous.

A mesic environment* – is a term used in ecology to describe an environment with a moderate amount of water.  Much of this part of Asia during the Late Cretaceous may be associated with a dry, arid environment, for example numerous types of other theropod fossils come from strata that represent almost desert-like conditions.  These fossils are found in the older Barun Goyot Formation which was laid down under more arid conditions.  The rocks in which the fossils of Gobiraptor were found consist mainly of river channel deposits, indicating that the palaeoenvironment changed and the environment became considerably wetter.

Thus, the finding of a new member of the Oviraptoridae family in the Nemegt Formation, which consists mostly of river and lake deposits, confirms that these dinosaurs were extremely well adapted to wet habitats.

Fragmentary Fossils and Skeletal Reconstruction of Gobiraptor minutus

Picture credit: PLOS One

Robust and Thickened Jaws Hint at a Dietary Specialism

Gobiraptor minutus, can be differentiated from other members of the Oviraptorosauria clade in having unusually robust and thickened jaws.  This unique mandibular morphology suggests that Gobiraptor was adapted to feeding on hard food items, it used its strong jaws to crush, indicating potential niche partitioning in the palaeoenvironment to reduce competition amongst small theropods and within the local population of oviraptorids.  Osteological analysis of the femur suggests that the fossil material represents a very young individual.

The phylogenetic analysis carried out by the researchers defines Gobiraptor as a derived oviraptorid closely related to three taxa from the Ganzhou region of southern China, but, ironically, the analysis suggests that it was rather distantly related to other Nemegt oviraptorids which, as the results of recent studies, are also not closely related to each other.

The authors propose that different dietary strategies may explain the wide taxonomic diversity and evolutionary success of this group of dinosaurs in this part of Asia.

Post-cranial Elements of G. minutus

Picture credit: PLOS One

The genus name honours the Gobi Desert, whilst the specific epithet is from the Latin for small, a reflection on the small size of the holotype.

The scientific paper: “A New Baby Oviraptorid Dinosaur (Dinosauria, Theropoda) from the Upper Cretaceous Nemegt Formation of Mongolia” by Sungjin Lee, Yuong-Nam Lee , Anusuya Chinsamy, Junchang Lü, Rinchen Barsbold and Khishigjav Tsogtbaatar published in PLOS One.

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