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/Palaeontological articles

Articles, features and information which have slightly more scientific content with an emphasis on palaeontology, such as updates on academic papers, published papers etc.

10 05, 2021

Billion-Year-Old Fossil from Scotland

By | May 10th, 2021|Dinosaur and Prehistoric Animal News Stories, Geology, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

A one-billion-year-old microfossil found in the Scottish Highlands has been shown to consist of two distinct cell types and could represent the earliest example of a multicellular animal ever recorded. Scientists from the University of Sheffield in collaboration with colleagues from Boston College (USA), have published a paper describing the discovery of a tiny fossil that provides a new perspective on the transition from single-celled organisms to more complex multicellular forms.

Image of Bicellum brasieri.
A highly magnified image of Bicellum brasieri preserved in petrographic thin sections. Two distinct cell shapes in the closely-packed cluster can be made out – elongate cells and more rounded ones. Picture credit: Professor Paul Strother (Weston Observatory of Boston College).

The photograph (above), shows an image of Bicellum brasieri, the cluster of cells measures around 20 microns in diameter, approximately 750 of these tiny organisms could sit on the head of a pin.

Lying Somewhere Between Single-celled and Multicellular Animals

The microscopic fossil material comes from the Mesoproterozoic-aged Diabaig Formation, which is exposed at Loch Torridon in the Northwest Scottish Highlands. It has been named Bicellum brasieri, the genus name being derived from the two types of cells (elongate and isodiametric) that were identified in the tightly grouped cell clusters.

Loch Torridon the site of the fossil discovery
The picturesque Loch Torridon a sea loch on the west coast of Scotland in the Northwest Highlands. The site of the Bicellum brasieri fossil discovery. Picture credit: Sheffield University.

Classified as a Holozoan

Writing in the academic journal “Current Biology” the researchers who include lead author Professor Charles Wellman from the Department of Animal and Plant Sciences (Sheffield University), have assigned this primitive lifeform to the Holozoa – a clade that includes all animals and their closest single-celled relatives but excludes fungi. If their interpretation is correct, then B. brasieri is distantly related to all living animals including our own species Homo sapiens.

Location map and outline of the stratigraphy of the Bicellum brasieri fossil discovery.
Location map and outline of the stratigraphy of the Bicellum brasieri fossil discovery. Picture credit: Strother et al.

A Remarkable Record of a Significant Development for Life on Earth

The shales of the Diabaig Formation were laid down at the bottom of a freshwater lake. The microfossils preserved in these rocks represent planktonic and benthic forms of microscopic life that existed around a billion years ago. The discovery suggests more complex lifeforms were evolving during this time in Earth’s history. The material could represent the earliest multicellular animal known to science.

Professor Wellman explained:

“The origins of complex multicellularity and the origin of animals are considered two of the most important events in the history of life on Earth, our discovery sheds new light on both of these. We have found a primitive spherical organism made up of an arrangement of two distinct cell types, the first step towards a complex multicellular structure, something which has never been described before in the fossil record.”

Bicellum fossil site location.
View of Diabaig Formation type section along the north shore of Loch Diabaig at the village of Lower Diabaig (B). The arrow marks the sample site. (C and D). View of dark shales (C) with lenticular, bedded phosphatic nodules in situ (D). Scale bar in (D), 5 cm. Picture credit: Strother et al.

Did the Animalia Evolve in the Sea or in Freshwater?

The exceptional preservation of the fossils enabled the research team to analyse them at both a cellular and subcellular level. The discovery of Bicellum brasieri challenges the long-held theory that complex life evolved in marine environments.

Professor Paul Strother, lead investigator of the research from Boston College stated:

“Biologists have speculated that the origin of animals included the incorporation and repurposing of prior genes that had evolved earlier in unicellular organisms. What we see in Bicellum is an example of such a genetic system, involving cell-cell adhesion and cell differentiation that may have been incorporated into the animal genome half a billion years later.”

This study has shed new light on the transition of single-celled organisms to more complex, sophisticated forms with cell specialisation.

The Boston College professor added:

“The discovery of this new fossil suggests to us that the evolution of multicellular animals had occurred at least one billion years ago and that early events prior to the evolution of animals may have occurred in freshwater like lakes rather than the ocean.”

The scientific paper: “A possible billion-year-old holozoan with differentiated multicellularity” by Paul K. Strother, Martin D. Brasier, David Wacey, Leslie Timpe, Martin Saunders and Charles H. Wellman published in Current Biology.

7 05, 2021

Nocturnal Dinosaurs Hunting in the Dark

By | May 7th, 2021|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Key Stage 3/4, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Scientists have proposed that the bizarre, chicken-sized alvarezsaurid Shuvuuia (S. deserti) had amazing eyesight and owl-like hearing, adaptations for a nocturnal hunter in its Late Cretaceous desert environment.

The Mongolian alvarezsaurid hunting at night
Shuvuuia deserti artist’s life reconstruction. Picture credit: Viktor Radermacher.

A Very Bizarre, Tiny Theropod

Named and described in 1998 from fossil material associated with the famous Djadochta Formation (Campanian faunal stage), Shuvuuia has been assigned to the Alvarezsauridae family of theropods. It may have been small (around 60 cm in length), but its skeleton shows a range of bizarre anatomical adaptations. It had long legs, a long tail, short but powerful forelimbs that ended in hands with greatly reduced, vestigial digits except for the thumb which was massive and had a large claw. The skull was very bird-like with disproportionately large orbits.

Photograph of fossilised Shuvuuia deserti skeleton.
Photograph of fossilised Shuvuuia deserti skeleton. Picture credit: Mick Ellison (American Museum of Natural History).

Writing in the academic journal “Science” a team of scientists led by Professor Jonah Choiniere (University of Witwatersrand, Johannesburg, South Africa), used sophisticated computerised tomography to examine the skull of Shuvuuia and to map this dinosaur’s sensory abilities, as part of a wider study into non-avian dinosaur sensory abilities.

Shuvuuia deserti fossil skull
Photograph of fossilised Shuvuuia deserti skull. Picture credit: Mick Ellison (American Museum of Natural History).

The international team of researchers used CT scanning and detailed measurements to collect data on the relative size of the eyes and inner ears of nearly 100 living bird and extinct dinosaur species. There are more than 10,000 species of bird (avian dinosaurs) alive today, but only a few have evolved sensory abilities that enable them to track and hunt prey at night. Owls are probably the best known, but not all owls are nocturnal. Kiwis hunt at night using their long, sensitive beaks to probe in the leaf litter for worms, whilst another bird endemic to New Zealand, the large, flightless Kakapo (a member of the parrots – Order Psittaciformes), is also nocturnal. Other birds active at night include the globally widespread black-capped night heron and the Stone-curlew (Burhinus oedicnemus) which is an occasional visitor to East Anglia in the UK.

To measure hearing ability, the team measured the length of the lagena, the organ that processes incoming sound information (known as the cochlea in mammals). The barn owl, which can hunt in complete darkness using hearing alone, has the proportionally longest lagena of any bird.

Barn owl skull CT scan showing lagena
Barn owl skull CT scan showing lagena. Picture credit: Jonah Choiniere/Wits University.

Assessing Vision

To examine vision, the team looked at the scleral ring, a series of bones surrounding the pupil, of each species. Like a camera lens, the larger the pupil can open, the more light can get in, enabling better vision at night. By measuring the diameter of the ring, the scientists could estimate how much light the eye can gather.

The researchers found that many carnivorous theropods such as large tyrannosaurs and the much smaller Dromaeosaurus had vision optimised for the daytime, and better-than-average hearing presumably to help them hunt. However, Shuvuuia, had both extraordinary hearing and night vision. The extremely large lagena of this species is almost identical in relative size to today’s barn owl, suggesting that Shuvuuia could have been a nocturnal hunter. With many predators sharing its Late Cretaceous desert environment, a night-time existence may have proved to be an effective strategy to avoid the attentions of much larger theropods.

Side by side comparison of the lagena of a Barn owl and Shuvuuia deserti
Side by side comparison of the lagena of a Barn owl (left) and Shuvuuia deserti (right). Picture credit: Jonah Choiniere/Wits University.

Commenting on the significance of this discovery, joint first author of the scientific paper, Dr James Neenan exclaimed:

“As I was digitally reconstructing the Shuvuuia skull, I couldn’t believe the lagena size. I called Professor Choiniere to have a look. We both thought it might be a mistake, so I processed the other ear – only then did we realise what a cool discovery we had on our hands!”

Extremely Large Eyes

The eyes of Shuvuuia were also remarkable. Skull measurements suggest that this little dinosaur had some of the proportionally largest pupils yet measured in birds or dinosaurs, suggesting that they could likely see very well at night.

Professor Jonah Choiniere holding a 3D Print of a Shuvuuia lagena
Professor Jonah Choiniere holding a 3D printed model of the lagena of Shuvuuia deserti. Picture credit: Jonah Choiniere/Wits University.

The Alvarezsauridae remain one of the most unusual of all the types of non-avian dinosaur known to science. Their place within the ecosystems of the Late Cretaceous remains controversial. Geographically widespread, a recently described alvarezsaurid from China Qiupanykus zhangi may have been a specialised ovivore (egg-eater), whilst other palaeontologists have postulated that these theropods used their strong forelimbs and large thumb claws to break into termite mounds. Perhaps, these small (most probably feathered), dinosaurs occupied a number of niches within Late Cretaceous ecosystems – including that of a nocturnal hunter of small vertebrates and insects.

Shuvuuia deserti artist's reconstruction.
Shuvuuia deserti artist’s reconstruction. Picture credit: Viktor Radermacher.

To read Everything Dinosaur’s blog article about Qiupanykus zhangi and the evidence behind the egg-eating theory: Did Alvarezsaurids Eat Eggs?

Everything Dinosaur acknowledges the assistance of a media release from the University of Witwatersrand in the compilation of this article.

The scientific paper: “Evolution of vision and hearing modalities in theropod dinosaurs” by Jonah N. Choiniere, James M. Neenan, Lars Schmitz, David P. Ford, Kimberley E. J. Chapelle, Amy M. Balanoff, Justin S. Sipla, Justin A. Georgi, Stig A. Walsh, Mark A. Norell, Xing Xu, James M. Clark and Roger B. J. Benson published in the journal Science.

1 05, 2021

The Regional and Temporal Diversity of Mongolian Dromaeosaurids

By | May 1st, 2021|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Earlier this year (January 2021), a new species of dromaeosaurid dinosaur was named and described from a partial skeleton excavated from deposits associated with the Barun Goyot Formation at Khulsan (Ömnögovi Province, Mongolia). The dinosaur, which was closely related to Velociraptor was named Shri devi. This little, fleet-footed carnivore was named after a female deity from Tibetan/Mongolian Buddhism.

Shri devi fossil material.
Pelvis and right hind limb of Shri devi IGM 100/980 after initial preparation whilst still in burlap jacket. Lateral view (top image) and ventral view (bottom view). Note scale bar = 5 cm.

Plotting the Regional Diversity of Dromaeosaurids

Although dromaeosaurid fossils are relatively rare, there have been several new dromaeosaur species described from this region of Asia in the last two decades. Shri devi is the first unequivocal dromaeosaurid taxon from the Late Cretaceous Barun Goyot Formation. Dating of the strata associated with these fossil finds has been problematical, but generally it is thought that the Djadochta Formation is the oldest, with the Barun Goyot Formation lying above it and the Nemegt Formation deemed the youngest formation of these three fossil bearing deposits.

Fossil Material Found in 1991

The Shri devi material consisting of a partially articulated skeleton including preserved right hind limb, elements from the left leg, the pelvis along with cervical, dorsal and caudal vertebrae from a single individual was discovered in 1991 by a joint expedition between the Mongolian Academy of Sciences and the American Museum of Natural History.

A scale drawing of Shri devi
Shri devi scale drawing. Although the skull is not known, it is thought that this dinosaur was closely related to Velociraptor and about the same size.

Dromaeosaurids although specious were rare within these palaeoenvironments, as many species are known from just one or two specimens. The discovery of S. devi has helped palaeontologists to map the regional and temporal differences of dromaeosaurs from this part of Late Cretaceous Asia.

Different dromaeosaurids of Mongolia and Inner Mongolia
Map showing the geographical and temporal distribution of Late Cretaceous dromaeosaurids from Mongolia and Inner Mongolia. The different dromaeosaurid biota of the Barun Goyot Formation and the Tugrugin Member/Bayn Dzak Member of the Djadochta Formation.

When formally described (Turner et al), it was noted that the second toe, the one that possessed the enlarged sickle-like claw, was proportionately larger than that seen in similar sized dromaeosaurs such as Velociraptor mongoliensis. Shri devi could have had a slightly bigger second toe claw than Velociraptor.

Hind foot of Shri devi
The foot of IGM 100/980 still in its burlap jacket (prior to final preparation). The large sickle claw on the second toe can be seen. Although approximately the same size as the closely related Velociraptor mongoliensis, the second toe claw of Shri devi seems to have been slightly larger. Note scale bar 2 cm.
30 04, 2021

Japan’s Second Hadrosaur

By | April 30th, 2021|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Scientists from the Hokkaido University Museum in collaboration with colleagues from the Okayama University of Science have named a second hadrosaurid from the Late Cretaceous of Japan. Described from a partial skeleton, Yamatosaurus izanagii lived at the same time as the first duck-billed dinosaur named from Japan (Kamuysaurus japonicus), but these two dinosaurs probably did not co-exist, instead Kamuysaurus may have been restricted to more northern coastal environments whilst the newly described Yamatosaurus may have been confined to more southerly habitats.

Yamatosaurus izanagii Life Reconstruction with more Advance Forms of Duck-billed Dinosaur in the Background
Yamatosaurus izanagii life reconstruction (centre), with a Lambeosaurinae representative (right) and a representative of the Saurolophinae (left), the dentition and shoulder bones suggest that Yamatosaurus is a basal member of the Hadrosauridae family and its discovery supports the idea that hadrosaurs evolved in Asia. Picture Credit: Masato Hattori.

Did the Hadrosauridae Originate in Asia or North America?

The researchers, who included Yoshitsugu Kobayashi, Ryuji Takasaki and Anthony R. Fiorillo (who wrote the scientific paper describing Kamuysaurus in 2019), plus Katsuhiro Kubota (Hokkaido University Museum), conducted a phylogenetic analysis suggesting that Yamatosaurus was a primitive member of the hadrosaur family. Intriguingly, the team also undertook a biogeographical analysis (plotting age of ornithopod fossil finds against geographical location). They conclude that basal hadrosaurids were widely distributed in both Asia and Appalachia (the landmass representing eastern North America). In addition, the scientists postulate that the discovery of Yamatosaurus supports the theory that the sub-families of more derived duck-billed dinosaurs the Lambeosaurinae and the Saurolophinae originated in Asia and that towards the end of the Cretaceous, basal hadrosaurids such as Plesiohadros djadokhtaensis (Mongolia), Tanius sinensis (C‌hina) and Yamatosaurus (Japan) continued to thrive in eastern Asia but were extinct elsewhere.

Data Suggests an Asian Origin for Hadrosaurs
A biogeographical analysis indicates that the Hadrosauridae may have originated in Asia. The discovery of Yamatosaurus izanagii in Japan supports the idea of an Asian original for that line of ornithopods that evolved into hadrosaurs.

Discovered in Marine Sediments

Amateur fossil collector Mr. Shingo Kishimoto discovered the fossilised remains in 2004, whilst exploring exposures of the Kita-ama Formation on the island of Awaji (Hyogo Prefecture). The fossil material consists of a dentary (lower jawbone), along with the surangular, neck bones, bones from the tail, cervical ribs and a coracoid plus some isolated teeth. Although hadrosaur fossils have been found in several locations in Japan (all four main islands – Hokkaido, Honshu, Shikoku, and Kyushu), they are, with the exception of the Kamuysaurus material, highly fragmentary consisting of teeth, portions of the limbs and vertebrae, this is only the second time that a new genus of duck-billed dinosaur has been erected from Japanese fossils.

The stratum from which the Yamatosaurus material was collected consists of marine mudstones of approximately the same age (early Maastrichtian), as the sediments in which Kamuysaurus was found.

Various views of the right dentary of Yamatosaurus
Right dentary of Yamatosaurus izanagii gen. et sp. nov. in lateral (a), medial (b), dorsal (c), ventral (d), and anterior (e) views.

Unique Traits and Basal Characteristics

Study of the nearly complete right dentary helped the researchers to erect a new, basal hadrosaur genus. Unlike other hadrosaurs Yamatosaurus had just one functional tooth in several battery positions and no branched ridges on the chewing surfaces. This suggests that Yamatosaurus evolved to feed differently compared to other duck-billed dinosaurs. Furthermore, the coracoid (that with the scapula would have formed the shoulder joint), shows traits linked to the movement away from a bipedal gait to becoming quadrupedal. This bone shows transitional characteristics that in later, more derived hadrosaurs, were more fully developed permitting these animals to become facultative bipeds (adopting a quadrupedal gait but able to run on their hind legs if required to do so).

To read Everything Dinosaur’s article from 2019 about the formal description of the first hadrosaur named from Japan (Kamuysaurus japonicus): Japan’s Greatest Fossil Dinosaur Gets a Name.

The scientific paper: “A new basal hadrosaurid (Dinosauria: Ornithischia) from the latest Cretaceous Kita-ama Formation in Japan implies the origin of hadrosaurids” by Yoshitsugu Kobayashi, Ryuji Takasaki, Katsuhiro Kubota and Anthony R. Fiorillo published in Scientific Reports.

20 04, 2021

New Species of Titanosaur Described

By | April 20th, 2021|Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

A new species of titanosaur has been named and described this week based on a partial skeleton unearthed in the Atacama Desert of northern Chile. The dinosaur has been named Arackar licanantay which translates as “Atacama bones” in the indigenous Kunza language.

Life Reconstruction Arackar licanantay
A life reconstruction of the newly described Late Cretaceous titanosaur Arackar licanantay from the Atacama Desert of northern Chile. Picture Credit: Museo Nacional de Historia Naturala Santiago (Chile).

The Second Titanosaur from Chile to be Named

As far as Everything Dinosaur team members are aware, this is the second titanosaur to be named and described from fossil remains found in Chile. The first was Atacamatitan chilensis, fossils of which were discovered at the beginning of this century. Although Atacamatitan is only known from fragmentary remains, the alignment, shape and skeletal position of the femur in relation to the hips are very similar to that of Arackar, so, Atacamatitan was probably closely related to Arackar licanantay, although its fossilised remains were found many hundreds of miles to the north.

Three Chilean Dinosaurs to Date

In total, three non-avian dinosaurs have been described from fossil remains discovered in Chile. The other dinosaur making up this trio is the peculiar Chilesaurus (Chilesaurus diegosuarezi), which is know from Jurassic deposits in the Aysén region of southern Chile. To read about the discovery of Chilesaurus: Chilesaurus – Shaking the Dinosaur Family Tree.

Chilesaurus scale drawing.
A scale drawing of the bizarre Late Jurassic dinosaur Chilesaurus. Chilesaurus is one of just three non-avian dinosaurs known from Chile (April 2021). Picture Credit: Everything Dinosaur.

Arackar licanantay – “Atacameño Bones”

Writing in the journal “Cretaceous Research”, scientists from the National Museum of Natural History (Chile), the Palaeontological Network of the University of Chile and the Dinosaur Laboratory of the National University of Cuyo describe a partial skeleton from the Upper Cretaceous (Campanian–Maastrichtian) beds of the Hornitos Formation, Atacama Region, of northern Chile. The holotype material consists of cervical and dorsal vertebrae along with limb bones and the ischium. The dinosaur’s name translates as “Atacameño bones” in the language of the indigenous Kunza people.

Arackar licanantay fossil material being excavated
Identifying a limb bone from the new species of titanosaur (Arackar licanantay). Picture credit: Universidad de Chile.

A Sub-adult Specimen

The fossils were found in the 1990s by national geologist Carlos Arévalo (National Geology and Mining Service), at a site around 45 miles south of the city of Copiapó, (Atacama Region). The bones represent a sub-adult individual estimated to have been around 6.3 metres in length. Although the adult size of Arackar is not known, it has been suggested that when fully grown, this herbivorous dinosaur would have been around 8-9 metres long, relatively small for a titanosaur.

Arackar was certainly no giant unlike other titanosaurs such as Dreadnoughtus, Notocolossus or Argentinosaurus which lived millions of years earlier. The discovery of this dinosaur helps to support the idea that towards the end of the Cretaceous (Campanian to Maastrichtian stages), these types of dinosaurs got smaller, perhaps in response to climate change.

Bone Dry

The fossil site might be located in one of the driest parts of the world, but when Arackar roamed (sometime between 80 and 66 million years ago, the age of the Hornitos Formation is uncertain), the climate was much more humid with the lush vegetation consisting of many types of flowering plant (angiosperms), conifers such as araucarias and podocarpaceae as well as ferns and cycads.

Chile may have only three non-avian dinosaurs described to date, but the scientists are confident that many more genera will be named. For example, close to the Arackar fossils, the remains of a second, as yet undescribed titanosaur were discovered.

Titanosaur fossil material (Arackar licanantay)
Fossil remains at the dig site, the preserved remains of limb bone. Another titanosaur specimen that has yet to be described was found close by. Picture Credit: Universidad de Chile.

Commenting on the significance of this discovery, Consuelo Valdés, the Minister of Culture, Arts and Heritage stated:

“This finding is a relevant opportunity to learn about and disseminate the value of our country’s palaeontological heritage, which is unique in the world. But, at the same time, we hope to motivate curiosity and interest in research in children and young people. Chile in the extreme north and south has palaeontological treasures still hidden in layers many millions of years old. These bones can tell the story of the animals and plants that have lived in our country long before the first human groups arrived here.”

South America – Home to the Titanosaurs

The scientific description of Arackar licanantay may have important implications for the taxonomy and phylogeny of the clade of derived and advanced titanosaurs known as the Lithostrotia. Of the eighty or so genera of titanosaurs named and described so far, fifty-five come from South America but most have been found to the east of the Andes in Brazil and Argentina.

Unique autapomorphies (traits) in the skeleton such as the shape of the dorsal vertebrae that would have given this dinosaur a very straight withers and back indicate that A. licanantay is not only closely related to Chile’s other titanosaur – Atacamatitan chilensis, but also to Rapetosaurus from the Late Cretaceous of Madagascar and Isisaurus (from India).

Titanosaur Taxonomic Relationships
The taxonomy of South American titanosaurs over time and geographical distribution. The red star represents the approximate placement of Arackar licanantay. Picture credit: Hechenleitner et al (Communications Biology) with additional annotation by Everything Dinosaur.

Co-author of the paper, Alexander Vargas (Palaeontological Network of the University of Chile), commented that it would be helpful if palaeontologists could understand the biogeographical distribution that allowed related titanosaurs to be so widespread.

Everything Dinosaur acknowledges the assistance of a media release from the Universidad de Chile in the compilation of this article.

The scientific paper: “Arackar licanantay gen. et sp. nov. a new lithostrotian (Dinosauria, Sauropoda) from the Upper Cretaceous of the Atacama Region, northern Chile” by David Rubilar-Rogers, Alexander O. Vargas, Bernardo González Riga, Sergio Soto-Acuña, Jhonatan Alarcón-Muñoz, José Iriarte-Díaz, Carlos Arévalo and Carolina S. Gutstein published in Cretaceous Research.

12 04, 2021

New Jurassic Pterosaur Reveals the Oldest Opposed Thumb

By | April 12th, 2021|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|1 Comment

An opposable thumb gives us apes a huge advantage, just ask a dog to hold a spoon for you, however, opposable thumbs are not just limited to gorillas, chimps, orangutans and our own genus Homo. Other apes have them too, as do some marsupials and tree frogs. In reality, opposed thumbs are rare in the Kingdom Animalia, but an international team of scientists including researchers from the University of Birmingham, have just described a new species of flying reptile and it’s the earliest example known to science of a vertebrate with an opposed thumb.

Kunpengopterus life reconstruction
Life reconstruction of K. antipollicatus. The opposed pollex could have been used for grasping food items, as well as clinging and hanging to trees. Picture credit: Zhao Chuang.

Kunpengopterus antipollicatus

The new Jurassic pterosaur has been named Kunpengopterus antipollicatus, it was discovered in the Tiaojishan Formation of Liaoning, China.

It is a small-bodied darwinopteran pterosaur, with an estimated wingspan of 85 cm. Most importantly, the specimen was preserved with an opposed pollex (“thumb”) on both hands. The species name “antipollicatus” means “opposite thumbed” in ancient Greek, in light of the opposed thumb of the new species. This is the first discovery of a pterosaur with an opposed thumb. It also represents the earliest record of a true opposed thumb in the fossil record.

Kunpengopterus antipollicatus fossil and line drawing
Fossil of Kunpengopterus antipollicatus, discovered in the Tiaojishan Formation of China. It is housed in the Beipiao Pterosaur Museum of China. Image credit: Zhou et al., 2021.

“Monkeydactyl”

Kunpengopterus lived in a forested environment approximately 160 million years ago. It was nicknamed “monkeydactyl” as a true opposed thumb (pollex) is extremely rare amongst extant reptiles, only chameleons possess opposed thumbs. They use their thumbs to help them climb, the researchers writing in the academic publication “Current Biology”, also suggest that Kunpengopterus evolved such dexterity to help it to climb.

In order to test the arboreal interpretation, the team analysed K. antipollicatus and other pterosaurs using a set of anatomical characters related to arboreal adaptation. The results support K. antipollicatus as an arboreal species, but not the other pterosaurs from the same ecosystem. This suggests niche-partitioning among these pterosaurs and provides the first quantitative evidence supporting the theory that at least some darwinopteran pterosaurs were arboreal.

Minimising Competition Amongst Pterosaurs

Lead author Xuanyu Zhou (China University of Geosciences) commented:

“Tiaojishan palaeoforest is home to many organisms, including three genera of darwinopteran pterosaurs. Our results show that K. antipollicatus has occupied a different niche from Darwinopterus and Wukongopterus, which has likely minimised competition among these pterosaurs.”

Photo and digital model of the left hand of K. antipollicatus, showing the opposed thumb.
Photo and digital model of the left hand of K. antipollicatus, showing the opposed thumb. Image credit: Zhou et al., 2021.

Micro-CT Imaging Assists in Discovery

Fion Waisum Ma, co-author of the study and PhD researcher (University of Birmingham) explained:

“The fingers of “Monkeydactyl” are tiny and partly embedded in the slab. Thanks to micro-CT scanning, we could see through the rocks, create digital models and tell how the opposed thumb articulates with the other finger bones. This is an interesting discovery. It provides the earliest evidence of a true opposed thumb, and it is from a pterosaur – which wasn’t known for having an opposed thumb”.

Everything Dinosaur acknowledges the assistance of a press release from the University of Birmingham in the compilation of this article.

The scientific paper: “A new darwinopteran pterosaur reveals arborealism and an opposed thumb” by Xuanyu Zhou, Rodrigo V. Pêgas, Waisum Ma, Xuefang Wei, Caizhi Shen and Shu’an Ji published in Current Biology.

9 04, 2021

A New Species of Ancient Mammal from Southern Chile

By | April 9th, 2021|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

A new species of Late Cretaceous South American mammal has been named and described. The omnivorous Orretherium tzen is only the second mammal from the Mesozoic known from Chile. The newly described O. tzen joins Magallanodon baikashkenke which was named in 2020. Orretherium has been described from a partial lower jawbone, which had 5 teeth in situ and a single isolated tooth found just a few metres away from the jaw fragment. It is thought to have been about the size of a modern skunk, although it was only distantly related to modern mammals.

Orretherium Life Reconstruction
Orretherium lived some 74-72 million years ago in South America. It shared its habitat with numerous dinosaurs including titanosaurs (seen in the background).

The Mammal Quarry

The fossils were found in exposures of the Dorotea Formation (late Campanian to early Maastrichtian faunal stages of the Late Cretaceous), on a small hill nicknamed “the mammal quarry”, reflecting the significance of the site in terms of Late Cretaceous mammalian fossil finds. Although the isolated tooth that helped describe this species was found close to the jaw fragment, the researchers cannot unambiguously refer this tooth to the same individual animal although it is highly probable taking in account their compatible size, wear and close proximity.

Orretherium fossil study.
Map (inset) showing the fossil find location, a reconstruction of the head of Orretherium along with a photograph of the jawbone and a computer enhanced image of the fossil.

Classified as a member of the Meridiolestida

Orretherium has been classified as a member of the Meridiolestida, an extinct group of mammals known from South America and Antarctica.

Co-author of the research paper published in the journal Scientific Reports, Sergio Soto-Acuña (University of Chile), commented:

“This mammal is a primitive lineage of the group of meridiolestids, very successful at the end of the Age of dinosaurs in South America. The jaw found has five teeth in place that indicate omnivorous habits, it probably fed on plants and insects”.

Looking for Late Cretaceous Mammals
Field work being carried out at “the mammal quarry” as scientists from the University of Chile in collaboration with researchers from Universidade Federal do Rio Grande do Sul (Brazil), Museo de La Plata (Argentina) and other South American academic institutions collaborated to produce the scientific paper describing Orretherium.

The scientific paper: “New cladotherian mammal from southern Chile and the evolution of mesungulatid meridiolestidans at the dusk of the Mesozoic era” by Agustín G. Martinelli, Sergio Soto-Acuña, Francisco J. Goin, Jonatan Kaluza, J. Enrique Bostelmann, Pedro H. M. Fonseca, Marcelo A. Reguero, Marcelo Leppe and Alexander O. Vargas published in Scientific Reports.

6 04, 2021

Trilobites had Gills on their Legs

By | April 6th, 2021|Dinosaur and Prehistoric Animal News Stories, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

Newly published research has provided palaeontologists with remarkable new evidence shedding light on the evolution of gill structures in the Arthropoda. Writing in the academic journal “Science Advances”, researchers from the University of California Riverside in conjunction with colleagues from the Indian Statistical Institute (Kolkata) and the American Museum of Natural History (New York), have demonstrated that some species of trilobite had gills on their upper limbs.

Trilobite Gill Fossil
One of the exceptionally rare trilobite specimens preserved in iron pyrite (fool’s gold) that led to the gill discovery. Picture Credit: Jin-bo Hou/University of California Riverside. The fossil is a specimen of Triarthrus eatoni from the famous Beecher’s trilobite bed from Oneida County, New York.

Exquisitely Preserved Fossils

Many thousands of species of trilobite have been named and described. However, very few fossils of these enigmatic, extinct members of the Arthropoda preserve soft parts of the animal’s bodies.

Trilobite fossils - the Selenopeltis slab.
Trilobites galore – the Selenopeltis slab from the Oxford University Museum of Natural History. The hard, exoskeletons of trilobites are extremely common fossils.

Fossils Preserved as Fool’s Gold Reveal New Information

The segmented limbs of trilobites were biramous, that is the limb was spilt into two branches. The function of the upper element of this limb has long been debated. It had been thought by some scientists that is served a respiratory function, but the evidence to support this hypothesis was lacking.

Remarkably detailed fossil specimens preserved in iron pyrite were subjected to scans using computerised tomography (CT scans). The computer generated images revealed dumbbell-shaped filaments in the upper limb branch that are morphologically comparable with gill structures in crustaceans.

A detailed view of a trilobite leg
A detailed view of a biramous (branched) trilobite leg showing the structures which have been interpreted as gill structures. Scale bar = 500 μm. Picture credit: Jin-bo Hou/University of California Riverside.

The Beecher’s Trilobite Bed

The beautifully preserved specimens with their soft parts replaced by pyrite come from the famous Beecher’s trilobite bed which is a Late Ordovician Lagerstätte with over 85% of the fossils found at the site representing the trilobite Triarthrus eatoni.

Lead author of the paper PhD student Jin-bo Hou (University of California Riverside) commented:

“Up until now, scientists have compared the upper branch of the trilobite leg to the non-respiratory upper branch in crustaceans, but our paper shows, for the first time, that the upper branch functioned as a gill”.

The research team mapped how blood would have filtered through chambers in these delicate structures, absorbing oxygen as it progressed through the tiny structures which measure around 30 microns across, that’s three times smaller than the diameter of a human hair.

These structures appear much the same as gills in modern marine arthropods like lobsters and crabs, but crucial anatomical differences were identified, helping scientists to better understand the phylogeny of the Trilobita within the arthropod phylum. Comparing the specimens in pyrite to another trilobite species (Olenoides serratus), gave the team additional information about how the filaments were arranged relative to one another and to the legs.

The researchers concluded that the upper limb’s partial articulation to the body via an extended membrane is morphologically comparable to the junction of the respiratory book gills of extant horseshoe crabs (Limulus). Furthermore, this morphology differentiates it from the typically robust junctions associated with crustaceans and the extinct sea scorpions.

The scientific paper: “The trilobite upper limb branch is a well-developed gill” by Jin-bo Hou, Nigel C. Hughes and Melanie J. Hopkins published in Science Advances.

3 04, 2021

Extra-terrestrial End-Cretaceous Impact Gave Rise to the Amazon Rainforest

By | April 3rd, 2021|Adobe CS5, Animal News Stories, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Key Stage 3/4, Main Page, Palaeontological articles|0 Comments

The Amazon rainforest is an extremely important low latitude habitat with a huge diversity of animals, fungi and plant species. Described as the “lungs of the planet”, this tropical rainforest is at the very centre of many global conservation efforts. New research suggests that it was the extra-terrestrial impact event some 66 million years ago that led to the rise of this angiosperm dominated ecosystem.

Earth impact event.
Cataclysmic impact event that led to the extinction of the dinosaurs and lots of other animal life. New research suggests that the dinosaur-killing bolide also gave rise to the Amazon rainforest ecosystem. Picture credit: Don Davis (commissioned by NASA).

K/Pg Extinction Event

Approximately 66 million years ago a rock from space smashed into our planet. This triggered a sudden mass extinction event devastating around 75% of all the animal and plant terrestrial species, many of which subsequently became extinct. At this time the dinosaurs, their cousins the pterosaurs and the majority of marine reptiles died out.

The end of the non-avian dinosaurs.
An artist’s impression of the bolide about to impact with the Gulf of Mexico 66 million years ago. This devastating event wiped out a large number of animals and plants, very probably contributing to the extinction of many different families including all the non-avian dinosaurs. Picture credit: Chase Stone.

Analysis of Fossil Pollen and Study of Fossil Leaves

Writing in the journal “Science”, researchers from the Southern Methodist University (Texas) and the University of Wyoming report on the study of tens of thousands of fossil pollen specimens along with thousands of leaf fossils from Cretaceous-aged strata and deposits laid down after the K/Pg extinction event. The scientists, which include co-author Dr Ellen Currano (Department of Botany, University of Wyoming), found that the types of plant creating tropical forests were very different pre and post the extra-terrestrial impact. In the Late Cretaceous tropical forests were dominated by conifers and they were much more open than the dense, angiosperm forests that came about during the Palaeocene.

Cretaceous maniraptora.
Study suggests the floral composition of tropical rainforests changed dramatically after the extra-terrestrial impact event. During the Late Cretaceous tropical forests were dominated by conifers and forest canopies were less dense. Picture Credit: Danielle Dufault.

A Thick Forest Canopy Denying Access to Light

The scientists discovered that the fossil pollen and leaves show a marked transition in tropical forest flora. After the extra-terrestrial impact forests developed a thick canopy blocking much of the light from reaching the ground and angiosperms became more dominant.

A view of a modern tropical rainforest canopy.
An aerial view of the dense angiosperm dominated canopy of a modern rainforest. Picture credit: BBC.

How Did These Changes Come About?

As well as the documenting the turnover in flora and the transition from one tropical forest environment to a different type of rainforest in the Palaeocene, the researchers propose three possible explanations for this change:

  1. The absence of large megaherbivores, specifically dinosaurs allowed plant densities in forests to increase. The extinction of giant plant-eating dinosaurs such as the Ceratopsia, hadrosaurs, armoured dinosaurs and the titanosaurs allowed plants to grow at lower levels as they were not being trampled or consumed by herbivorous dinosaurs.
  2. Several types of fern and conifer became extinct during the K/Pg transition permitting new types of angiosperm (flowering plants) to evolve and exploit the vacated niches.
  3. Falling ash from the impact enriched soils throughout the tropics, provided an advantage to faster-growing angiosperms.
The floral composition of rainforests radically altered after the K/Pg extinction event.
The floral composition of rainforests radically altered after the K/Pg extinction event. Picture Credit: BBC.

The scientists conclude that the three hypotheses are not mutually exclusive and that a combination of factors could have led to the change in the flora as recorded in the fossil record.

A Significant Lesson for Today

Today, a rapidly changing climate, largely caused by the actions of our own species is having a dramatic effect on the world’s forests. The researchers note that the fossil record demonstrates that rainforests do not simply “bounce back”, after a catastrophe. They can take millions of years to recover and a very different type of ecosystem is likely to emerge.

The scientific paper: “The impactful origin of neotropical rainforests” by Bonnie F. Jacobs and Ellen D. Currano published in the journal Science.

1 04, 2021

Llukalkan aliocranianus – New Abelisaurid from Argentina

By | April 1st, 2021|Adobe CS5, Dinosaur and Prehistoric Animal News Stories, Dinosaur Fans, Main Page, Palaeontological articles, Photos/Pictures of Fossils|0 Comments

A team of international researchers have named and described a new species of fearsome, meat-eating dinosaur based on a partial skull found in 2015 in Neuquén Province (northern Patagonia). The dinosaur is a member of the Abelisauridae family and it has been named Llukalkan aliocranianus. The genus name is from the local Mapuche dialect and translates as “one who causes fear”. Not only was Llukalkan a likely apex predator, its discovery helps to confirm that the abelisaurs were one of the most important and significant predators in South America during the Late Cretaceous.

A Life Reconstruction of the Abelisaurid Dinosaur Llukalkan aliocranianus
A life reconstruction of the newly described abelisaurid from Argentina Llukalkan aliocranianus. Picture credit: Jorge Blanco and the Journal of Vertebrate Paleontology.

Found in Close Proximity to Viavenator exxoni

The well-preserved skull was found in outcrops of the Bajo De La Carpa Formation at the La Invernada fossil site. The strata at this location were laid down approximately 85 million years ago (Santonian faunal stage of the Late Cretaceous) and the bones were found close to the location of an earlier abelisaurid discovery (Viavenator exxoni), which had been found by some of the scientists that also participated in the Llukalkan study.

Assessment of the lacrimal bone suggest that this skull material represents a sub-adult animal and comparison with other abelisaurids such as Carnotaurus indicates that Llukalkan may have been around five metres in length, making it slightly smaller than Viavenator which is estimated to have been around six metres long.

Skull Bones associated with Llukalkan aliocranius
A view of the cranial material of the holotype (Llukalkan aliocranianus) – view in left lateral view with line drawing showing where the bones fit with the rest of the skull. Unique rugose and roughened patches on the skull bones confirmed that the scientists were dealing with a new species.

Writing in the peer reviewed academic publication the “Journal of Vertebrate Paleontology”, the researchers which included Federico A. Gianechini, Leonardo S. Filippi and Ariana Paulina-Carabajal identified a number of autapomorphies within the skull material that led them to confidently assign a new species. The trivial name is derived from the Latin for “different skull”.

Abelisaurids “Top Dogs”

Something like ten different genera of abelisaurid dinosaur have been discovered in Patagonia to date. The scientists state that Llukalkan and Viavenator were probably contemporaneous and they help to demonstrate the dominance of this type of theropod dinosaur in the Late Cretaceous of Argentina. Both Viavenator and the newly described Llukalkan were closely related, both have been assigned to the Abelisauridae clade – the Furileusauria which includes the geologically much younger and much larger Pycnonemosaurus (P. nevesi), fossils of which come from Brazil.

Megaraptors for Company

It is likely that these two furileusaurian abelisaurids probably shared their environment with another type of large theropod hypercarnivore. Fossils of the megaraptor Tratayenia rosalesi, which was described in 2018, are also associated with the Santonian-aged strata of the Bajo de la Carpa Formation, albeit the Tratayenia material was found at a different location.

Tratayenia stalking prey.
An illustration of the new Late Cretaceous megaraptoran dinosaur Tratayenia. Picture credit: Andrea McAfee (Carnegie Museum of Natural History).

At around eight metres in length (possibly even bigger), T. rosalesi was a formidable predator. Whether the abelisaurids were the “top dogs” when it came to the food chain remains uncertain. However, with the discovery of Llukalkan so close to the fossils of Viavenator, it does suggest that these types of theropods were extremely successful predators.

To read Everything Dinosaur’s earlier article on the discovery of Tratayenia rosalesi: A New Megaraptoran Theropod from Argentina.

The scientific paper: “A New Furileusaurian Abelisaurid from La Invernada (Upper Cretaceous, Santonian, Bajo De La Carpa Formation), Northern Patagonia, Argentina” by Federico A. Gianechini, Ariel H. Méndez, Leonardo S. Filippi, Ariana Paulina-Carabajal, Rubén D. Juárez-Valieri and Alberto C. Garrido published in the Journal of Vertebrate Paleontology.

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