Team members from Everything Dinosaur have spotted frogspawn in the office pond this morning. The overnight gales and heavy rain have not deterred the common frogs (Rana temporaria) and they have spawned.
Frogspawn in Everything Dinosaur’s office pond. Team members estimate that there were more than ten Common frogs (Rana temporaria) in the pond.
An Early Spawning
With eggs being laid on the 11th March (2021), this is a little earlier than in recent years. For example, last year (2020), frogspawn was spotted on March 19th. In 2018, frogspawn was spotted on the 17th March, the last time the frogs spawned on the 11th March was 2017.
A spokesperson from the UK-based dinosaur model company stated:
“We keep a close watch on the office pond at this time of year and when the frogs spawn we record the date and then we monitor the progress of the tadpoles when they hatch and become more mobile.”
The frogs in the office pond are Common frogs, sometimes referred to as the European common frog or the grass frog (Rana temporaria).
Our thanks to Cooper, a dinosaur fan who commented on one of our blog posts highlighting one of his favourite dinosaurs, the diminutive Anchiornis (A. huxleyi), the scientific name translating as “Huxley’s near bird”.
An illustration of the feathered dinosaur Anchiornis huxleyi. Picture credit: Julius Csotonyi.
Controversial Taxonomy
Many palaeontologists believe that this small dinosaur known from Upper Jurassic deposits associated with the Tiaojishan Formation of Liaoning (north-eastern China), is a basal member of the Paraves clade, a part of the Maniraptora that incorporates the dromaeosaurids, the troodontids and the avialans, those dinosaurs that lead directly to the evolution of modern birds. The exact taxonomic position of this dinosaur remains controversial.
Ancient, feathered creature. An Anchiornis fossil from the famous Tiaojishan Formation of Liaoning Province (north-eastern China). Picture credit: CAS.
A Fan of Anchiornis
Cooper produced a near perfect copy of one of Everything Dinosaur’s numerous articles on Anchiornis huxleyi. The many fossil specimens associated with this species has led to several different types of scientific research paper being published about Anchiornis, focusing on ontogeny, phylogeny and behavioural aspects of this little theropod.
Everything Dinosaur has written a number of blog posts (at least fourteen), about Anchiornis with our first article being published in 2009.
The PNSO “Luffy” the Anchiornis dinosaur model from the “Age of Dinosaurs” model range. PNSO introduced a series of prehistoric animal models, many of which were based on Chinese fossil discoveries.
A spokesperson for the UK-based specialist mail order company stated:
“Our thanks to Cooper for reaching out to us. We deal with hundreds of enquires every week and we do our best to respond to all those that require a reply. We are glad that Cooper found our work on Anchiornis huxleyi so thought-provoking and informative.”
Anchiornis huxleyi
Named and described shortly before Everything Dinosaur published its first blog post about this dinosaur, the species name honours Thomas Henry Huxley, an early champion of Darwin’s theory of evolution.
The Chinese company PNSO is one of the few mainstream model makers to have made an Anchiornis figure. “Luffy” the Anchiornis (pictured above), is one of a series of 48 models featured in the “Age of Dinosaurs – Toys that Accompany your Growth” model range. It also features in the huge PNSO Age of Dinosaurs box set.
PNSO special edition gift box features 48 prehistoric animal models including “Luffy” the Anchiornis.
To view the PNSO Anchiornis model and the other prehistoric animal figures available from Everything Dinosaur: PNSO Age of Dinosaurs.
The PNSO Domingo the Carnotaurus dinosaur model has already attracted rave reviews from collectors and fans of dinosaur models. This 5-star rated figure has been described as “a beautiful model, at this moment the most accurate depiction of Carnotaurus” and “an amazing model, both colour and sculpt are stunning” by reviewers on Everything Dinosaur’s website.
The PNSO Carnotaurus model stands perfectly stable without the use of the transparent stand which is supplied with the figure. However, Everything Dinosaur recommends that the support stand is used when the model is put on display.
Carnotaurus sastrei
This replica of a Late Cretaceous South American abelisaurid has certainly turned heads. The model is exquisitely detailed and so well made that the figure stands perfectly on a flat, level service without the aid of the transparent support stand that is supplied with this dinosaur model.
A lateral view of the PNSO Domingo the Carnotaurus. This new for 2021 dinosaur model has been highly praised by fans of dinosaurs.
An Articulated Lower Jaw
Like a lot of the new theropod figures from PNSO, Domingo the Carnotaurus has an articulated lower jaw. The model designers have been careful to depict those famous horns over the eyes (from which this dinosaur’s name is derived, due to their superficial similarity to the horns of a bull). The colouration chosen shows evidence of countershading and the use of black stripes gives this figure real presence. Although the jaw of Carnotaurus is relatively small and delicate, the designers have taken heed of the fossil evidence and equipped their model with a narrow jaw, located in a disproportionately deep skull.
A close view of the head of the PNSO Carnotaurus model showing the delicate lower jaw, the deep skull and those famous horns over the orbits.
A spokesperson from Everything Dinosaur commented:
“Fans of dinosaur models and figure collectors have really been looking forward to the arrival of the PNSO Domingo the Carnotaurus replica. It had a lot of hyperbole to live up with some collectors stating that PNSO was the most improved model manufacturer on the market. With the first reviews for this new for 2021 figure posted up on our website, it seems that collectors have not been disappointed.”
The PNSO Domingo the Carnotaurus dinosaur model has an articulated lower jaw.
A Range of New PNSO Dinosaurs
Domingo the Carnotaurus is one of a range of new dinosaur figures which also includes a replica of the theropod from China called Qianzhousaurus.
The PNSO A-Shu the Qianzhousaurus dinosaur model faces off against the PNSO Domingo the Carnotaurus. These two models both have articulated lower jaws and are part of a range of new model introductions from PNSO.
To view the PNSO Domingo the Carnotaurus model and the rest of the prehistoric animals in the PNSO range: PNSO Age of Dinosaurs.
Stunning fossil plants preserved within a volcanic ash fall in China have shed light on an evolutionary race 300 million years ago, which was eventually won by the seed-bearing plants that dominate the flora of our planet today.
New research into fossils found at the “Pompeii of prehistoric plants”, in Wuda, Inner Mongolia, reveals that the plants, called Noeggerathiales, were highly-evolved members of the lineage from which came seed plants.
A reconstruction of the crown of Paratingia wuhaia. A newly described prehistoric plant from the Early Permian.
The Importance of Noeggerathiales
Noeggerathiales were important peat-forming plants that lived around 325 to 251 million years ago (Late Carboniferous to the end of the Permian). Understanding their relationships to other plant groups has been limited by poorly preserved examples until now. The beautiful fossils found in China have allowed experts to work out that Noeggerathiales are more closely related to seed plants than to other fern groups.
No Evolutionary Dead-end
No longer considered an evolutionary cul-de-sac, they are now recognised as advanced tree-ferns that evolved complex cone-like structures from modified leaves. Despite their sophistication, Noeggerathiales fell victim to the profound environmental and climate changes of 251 million years ago that destroyed swamp ecosystems globally (End Permian mass extinction event).
Fossil specimen of the new species (Paratingia wuhaia) preserving the crown of the tree with leaves and its fertile organs attached to the stem.
Co-author of the scientific paper, published this month in the Proceedings of the National Academy of Sciences (PNAS), Dr Jason Hilton, Reader in Palaeobiology at the University of Birmingham’s Institute of Forest Research, commented:
“Noeggerathiales were recognised as early as the 1930s, but scientists have treated them as a ‘taxonomic football’, endlessly kicked around without anyone identifying their place in the story of life. The spectacular fossil plants found in China are becoming renowned as the plant equivalent of Pompeii. Thanks to this slice of life preserved in volcanic ash, we were able to reconstruct a new species of Noeggerathiales that finally settles the group’s affinity and evolutionary importance.”
A Stark Warning for Us
The researchers comment that the fate of advanced Noeggerathiales is a stark reminder of what can occur when a sophisticated and seemingly well-adapted form of life is faced with rapid, dramatic environmental change.
The scientists studied complete Noeggerathiales preserved in a bed of volcanic ash 66 cm thick formed 298 million years ago (Early Permian), smothering all the plants growing in a nearby swamp. The ash stopped the fossils from rotting or being consumed and preserved many complete individuals in microscopic detail.
A life reconstruction of the swamp (yellow arrows indicate the newly named plant species (Paratingia wuhaia).
Lead-Author Jun Wang, (Nanjing Institute of Geology and Palaeontology), added:
“Many specimens were identified in excavations in 2006-2007 when a few leaves were visible on the surface of the ash. It looked they might be connected to each other and a stem below – we revealed the crown on site, but then extracted the specimens complete to take them back to the lab. It has taken many years to study these fully and the additional specimens we have found more recently. The complete trees are the most impressive fossil plants I have seen and because of our careful work they are also some of the most important to science.”
An Extensive Ancestral Lineage
The research team postulate that that the ancestral lineage from which seed plants evolved diversified alongside the earliest seed plant radiation during the Devonian, Carboniferous and Permian periods, and did not rapidly die out as previously thought.
Everything Dinosaur acknowledges the assistance of a press release from the University of Birmingham in the compilation of this article.
The scientific paper: “Ancient noeggerathialean reveals the seed plant sister group diversified alongside the primary seed plant radiation” by Jun Wang, Jason Hilton, Hermann W. Pfefferkorn, Shijun Wang, Yi Zhang, Jiri Bek, Josef Pšenička, Leyla J. Seyfullah and David Dilcher published in the Proceedings of the National Academy of Sciences.
An open-access paper has recently been published in the on-line academic journal PLOS One announcing the discovery of a new species of rebbachisaurid sauropod. The newly described dinosaur named Dzharatitanis kingi is the first member of the Rebbachisauridae family to have been found in Asia. Rebbachisaurids are known from Europe, Africa South America and possibly North America. They are related to diplodocids such as Brontosaurus and Apatosaurus and most palaeontologists group them in the Diplodocoidea superfamily along with the Diplodocidae and the rare and enigmatic Dicraeosauridae dinosaurs.
Dzharatitanis kingi the first rebbachisaurid to be described from Asia. Picture credit: Alexander Averianov. The large pterosaurs walking in the same direction as the sauropod probably represent the azhdarchid Azhdarcho, the only pterosaur to have been described to date from fossils found in the Bissekty Formation.
Described from a Single Fossil Bone
Described from a single, well-preserved tail bone from the base of the tail (anterior caudal vertebra), this herbivore is estimated to have been around 15 to 20 metres in size. The fossil bone was found in 1997, by David Ward and one of the authors of the scientific paper, Hans-Dieter Sues, during the Uzbekistan/Russian/British/American/Canadian exhibition to map and document Late Cretaceous Dzharakuduk escarpment outcrops associated with the Bissekty Formation in the Kyzylkum Desert of Uzbekistan.
Dzharatitanis is (as far as Everything Dinosaur team members are aware), the first sauropod to have been formally described from the Bissekty Formation.
The strata associated with the fossil find are believed to be around 90 million years of age (Turonian stage of the Late Cretaceous). D. kingi represents one of the geologically youngest known rebbachisaurids.
Dzharatitanis kingi, USNM 538133 (holotype), anterior caudal vertebra in posterior (A), right lateral (B), and anterior (C) views. Note scale bar = 10 cm. Picture Credit: Alexander Averianov and Hans-Dieter Sues
“Dzharakuduk titan”
The genus name is derived from the Dzharakuduk escarpment and translates as “Dzharakuduk titan”, whereas the species name honours the late Dr Christopher King who did much to map and document the geology of the Cretaceous-aged strata of central Asia.
Numerous “pencil-shaped” teeth along with isolated bones indicate the presence of sauropods within the Bissekty Formation however, D. kingi is the first member of the Sauropoda to be described. The caudal vertebrae of these types of dinosaur are very diagnostic. Their shape and characteristics help palaeontologists to identity related genera and this single fossil bone, believed to represent the first bone of the tail was sufficient to merit the erection of a new dinosaur species.
The sauropods from the Bissekty Formation now comprise at least two taxa, the rebbachisaurid Dzharatitanis kingi and an indeterminate and as yet unnamed titanosaur.
The scientific paper: “First rebbachisaurid sauropod dinosaur from Asia” by Alexander Averianov and Hans-Dieter Sues published in PLOS One.
A team of international scientists including Steve Brusatte (University of Edinburgh), have confirmed the presence of troodontids in the Late Cretaceous of Europe. A new species of troodontid has been erected based on the discovery of a single metatarsal bone (the second metatarsal bone from the right foot), from Late Cretaceous strata in the Talarn Formation exposed at the Sant Romà d’Abella site in the southern Pyrenean region of Spain. This new dinosaur has been named Tamarro insperatus.
A life reconstruction of the first troodontid confirmed from the Late Cretaceous of Europe Tamarro insperatus.
Picture Credit: Oscar Sanisidro
Found in 2003
The single fossil bone indicating the presence of troodontids in Europe was found in September 2003 by a team of palaeontologists from the Museu de la Conca Dellà (Lleida, Isona, Spain) at the Sant Romà d’Abella site (Spain). It was found in fluvial floodplain deposits believed to have been laid down just 200,000 years or so before the K-Pg mass extinction event.
The fossil bone was found in the same horizon as plant fossils and the type specimen of the lambeosaurine Pararhabdodon isonensis, the metatarsal was found in close proximity to the Pararhabdodon type specimen, these are the only two vertebrates known from this site.
The Dinosaurs from the Late Cretaceous of Europe
During the Late Cretaceous, high sea levels ensured that much of the European landmass we know today was underwater. Numerous islands existed, creating an extensive archipelago and several dinosaurs associated with these islands exhibit dwarfism or other unusual features associated with isolated ecosystems. Very little is known about the Theropoda that inhabited these islands. For example, the presence of troodontids in Europe has been debated for a long time. Several troodontid-like and Paronychodon teeth (a nomen dubium taxa referred by some to the Troodontidae), were recovered from the Campanian and Maastrichtian deposits of the ancient Hateg (Romania) and Ibero-Armorican (Portugal, France and Spain) islands, but this fossil bone provides definitive, unequivocal proof of these theropods being present in the Late Cretaceous of Europe.
Views of the second metatarsal (metatarsal II from the right foot), plus line drawing showing the skeletal position of the bone.
Picture Credit: Albert G. Sellés (Institut Català de Paleontologia Miquel Crusafon/Museu de la Conca Dellà)
A Basal Troodontid with Asian Origins
An analysis of the bone and a phylogenetic assessment suggests that Tamarro is a basal member of the Troodontidae family and most likely a representative of the Asian subfamily the Jinfengopteryginae. The research team speculate on how a dinosaur with relatives in Asia could have become established in Europe. Maastrichtian troodontids like Tamarro could have reached Europe during the Cenomanian faunal stage and persisted on these islands until the K-Pg extinction event.
Estimated at around two metres in length Tamarro is around twice the size of other related troodontids. A close examination of the bone (cross-sectional histology), reveals that the metatarsal came from a subadult animal that was growing rapidly. Although troodontids are known to have fast growth rates, Tamarro seemed to be growing much quicker than other members of the Troodontidae, perhaps reaching full maturity in around two years.
Growth rate of Tamarro insperatus compared to other members of the Maniraptora. When compared to other taxa from the group of dinosaurs most closely related to birds (including Aves), Tamarro has a rapid growth rate reaching a subadult state in around one year.
The genus name is derived from the Catalan word “Tamarro” which refers to a small, mythical creature from local folklore. The species or trivial name “insperatus” is from the Latin for unexpected, a reference to the unexpected discovery of the fossil bone.
The scientific paper: “A fast-growing basal troodontid (Dinosauria: Theropoda) from the latest Cretaceous of Europe” by Albert G. Sellés, Bernat Vila, Stephen L. Brusatte, Philip J. Currie and Àngel Galobart published in Scientific Reports.
As we are preparing for the arrival of the latest batch of new for 2021 PNSO prehistoric animal models team members at Everything Dinosaur have been busy completing their Pinacosaurus fact sheet that will be sent out with sales of this armoured dinosaur model.
Bart the PNSO Pinacosaurus Dinosaur Model
The new for 2021 PNSO Bart the Pinacosaurus dinosaur model (lateral view). This model is expected in stock at Everything Dinosaur on March 8th, 2021.
PNSO Pinacosaurus grangeri
Pronounced “pin-ack-oh-sore-us”, this Late Cretaceous armoured dinosaur is one of the best known of all the members of the Ankylosauridae family. Measuring up to five metres in length, this herbivorous, armoured dinosaur is known from numerous specimens representing juveniles and adult animals.
Everything Dinosaur’s Scale Drawing of Pinacosaurus
Everything Dinosaur’s scale drawing of the armoured dinosaur from Asia – Pinacosaurus grangeri. The dinosaur is estimated to have measured up to five metres in length and weighed approximately 1.9 tonnes, that is about as heavy as an extant Indian rhinoceros (Rhinoceros unicornis).
What Other PNSO Figures are Due in Stock?
About a dozen or so PNSO prehistoric animal figures are due to arrive at Everything Dinosaur’s new warehouse on Monday (8th March 2021). Team members are not quite sure when the figures will arrive but they are all on standby to help get them unloaded and on-line as quickly as possible.
All eight of the new for 2021 dinosaur models should be on this shipment plus some of the earlier models that were available at the factory when the container was being made ready for sending to the docks.
PNSO Pinacosaurus Dinosaur Model (Dorsal View)
The new for 2021 PNSO Bart the Pinacosaurus dinosaur model (dorsal view). The beautifully detailed armour on this model can be clearly seen. This figure is expected in stock at Everything Dinosaur within 72-hours (Monday, 8th March 2021).
PNSO Age of Dinosaurs (Prehistoric Animal Figures)
PNSO have rapidly built an excellent reputation for their dinosaur and prehistoric animal models. Everything Dinosaur has worked with this Chinese company for many years and a spokesperson from the UK-based specialist mail order company stated:
“We are expecting A-Shu the Qianzhousaurus, Perez the Machairoceratops, along with the other new horned dinosaur figure A-Qi the Sinoceratops, plus Domingo the Carnotaurus and the new Wilson T. rex figure. In addition, the three new armoured dinosaurs Isaac the Sauropelta, Rosana the Miragaia and of course Bart the Pinacosaurus.”
However, given all the current difficulties with global logistics at the moment, team members will be thoroughly checking over the shipment prior to putting these models on-line.
The spokesperson added:
“There are so many problems with shipping goods at the moment. For example, this container was held at the UK port for several days simply because of the amount of congestion at the dockside. The inspection by UK Customs and Trading Standards did not hold up the shipment for too long, but we know that a number of the cartons will have been opened as part of the checking process so we will be spending time once the delivery has arrived in sorting out the boxes before these models can be put into our on-line shop.”
To view the range of PNSO prehistoric animal models available from Everything Dinosaur: PNSO Age of Dinosaurs.
As today (4th March 2021), is recognised in many countries as World Book Day, team members at Everything Dinosaur have been busy posting up on social media book recommendations for those readers interested in the Dinosauria and other archosaurs.
“The Encyclopedia of Dinosaurs – The Sauropods”
The Encyclopedia of Dinosaurs – The Sauropods front cover. A superb book all about the Sauropodomorpha and their near relatives by Rubén Molina-Pérez and Asier Larramendi.
Crammed with Fascinating Dinosaur Facts
The Encyclopedia of Dinosaurs, the sauropod edition, is packed full of fascinating information and it has been laid out in an easy to follow format with copious illustrations and lots of diagrams to help elucidate the text.
Packed with Super Sauropod Facts and Figures
Lots of fascinating facts about the sauropods inside the book.
Written by Rubén Molina-Pérez and Asier Larramendi, the book documents the rise of the long-necked giants from their much smaller ancestral forms, classifies and characterises them and even examines their impact on modern culture. From viewing them as slow and sluggish reptiles inevitably doomed to extinction, the authors document the fossil evidence that shows how well-adapted these dinosaurs were to their environment.
How we View Sauropods Has Changed
How society views the sauropods has changed. From viewing them as amphibious, living in lakes and rivers, to recognising them as land animals no longer considered slow, clumsy creatures that were doomed to extinction.
A spokesperson from Everything Dinosaur commented:
“This is a stunning and comprehensive guide to the Sauropodomorpha aimed at dinosaur enthusiasts. Expect lots of information about famous dinosaurs such as Brachiosaurus, Apatosaurus and Mamenchisaurus plus lots of insights into their lives and behaviours.”
Amazing Dinosaur Illustrations
Pampadromaeus – perhaps the smallest known sauropodomorph. The book provides plenty of information on some of the less well-known dinosaurs such as the basal sauropodomorph Pampadromaeus barberenai – regarded as one of the smallest members sub-order of the Dinosauria.
Documenting the Dinosauria
Authors Rubén Molina-Pérez and Asier Larramendi demonstrate their extensive knowledge by providing information often omitted from other books about long-necked dinosaurs. For example, as well as looking at dinosaur diets, the writers examine related facets such as sauropod bite forces.
The Book Examines the Bite Forces of Sauropods such as Diplodocus
The book provides lots of fascinating information on the sauropods such as details of estimated bite force by genera.
Highly Recommended
This is a one-of-a-kind compendium that covers all the known sauropod species at the time of publication, plus it provides details on one or two that have yet to be formally described.
For dinosaur fans, this book is highly recommended.
Scientists have identified a new species of titanosaur from fragmentary fossil remains found in northern Patagonia (Argentina). Readers of Everything Dinosaur’s blog will know that there have been many amazing titanosaur fossil discoveries from Argentina featured on this site. Some of the largest dinosaurs known to science have been described from fossil material found in Patagonia, giants such Argentinosaurus, Patagotitan and Dreadnoughtus as well as slightly smaller ones, for example Sarmientosaurus (S. musacchioi)* with its beautifully preserved skull and the recently described Punatitan and Bravasaurus**.
However, the new species named Ninjatitan zapatai, is perhaps much more significant when it comes to the Titanosauria clade. The fossils from this titanosaur come from the Lower Cretaceous Bajada Colorada Formation located in Neuquén Province. Ninjatitan roamed Argentina around 140 million years ago, as such it could be the earliest known titanosaur sauropod, further strengthening the theory that these types of sauropod originated from South America.
A Life Reconstruction of Ninjatitan zapatai
Ninjatitan zapatai life reconstruction.
Picture Credit: Jorge A. González courtesy of Fundación Azara.
Known from Fragmentary Remains
In 2014, Jonatan Aroca, a technician at the Ernesto Bachmann Municipal Museum, was exploring a rocky outcrop close to the Limay River between the towns of Picún Leufú and Piedra del Águila (Neuquén Province), when he spotted a large fossil bone eroding out of the sediments. This fossil proved to be the scapula (shoulder blade) and subsequent excavations revealed two dorsal vertebrae, a fibula, part of the femur and a tail bone. After the materials had been extracted and technically prepared and cleaned in the laboratory of the Chocón Museum, it was determined that this was a new species of sauropod titanosaur.
The Scapula (Shoulder Blade) is Excavated
The scapula of Ninjatitan is slowly and carefully excavated.
Picture Credit: Jorge A. González courtesy of Fundación Azara.
The Origin of the Titanosauria
In recent years, several studies have postulated that the origin of the Titanosauria clade would have been in the early Cretaceous (about 140 million years ago) and somewhere in South America. However, until now, these hypotheses were not clearly supported by fossil evidence, but were the results of theoretical studies with statistical models.
Lead author of the scientific paper, Pablo Gallina, a CONICET (Consejo Nacional de Investigaciones Científicas y Técnicas), palaeontologist from the Palaeontology Area of the Azara Foundation and Maimonides University commented:
“This finding allows us to reinforce the idea that titanosaurs appeared in South America. It was thought that they might have first appeared there, but there was no real evidence, with fossils, to prove it. This finding gives more support to this theory.”
The Stunning Landscape of the Limay River
The Lower Cretaceous Bajada Colorada Formation in Neuquén Province, Argentina. The rocks from which the Ninjatitan fossil material came are believed to be around 140 million years old.
Picture Credit: Jorge A. González courtesy of Fundación Azara.
Everything Dinosaur acknowledges the assistance of a media release from CONICET in the compilation of this article.
At an estimated 20 metres in length Ninjatitan may not be the largest titanosaur from Argentina, but because of its age, it might just prove to be one of the most important South American titanosaur discoveries ever made.
The scientific paper: “The Earliest Known Titanosaur Sauropod Dinosaur” by Pablo Ariel Gallina, Juan Ignacio Canale and José Luis Carballido published in Ameghiniana.
Researchers from the University of Nebraska-Lincoln and University of New Mexico have come up with a novel explanation as to why there are so few medium-sized carnivorous dinosaurs found in the fossil record.
In a scientific paper published in the academic journal “Science” they propose that sub-adults and juveniles of much larger species out-competed similarly sized adults of medium-sized meat-eating dinosaurs resulting in a transformation of dinosaur community populations.
Comparing Mammalian and Dinosaurian Carnivorous Communities
Did juvenile and sub-adult hypercarnivores drive out the medium-sized meat-eaters?
Picture credit: Schroeder et al (Science)
Communities with Megatheropods Lacked Medium-sized Carnivores
The researchers identified that based on the known fossil record, communities of dinosaurs with super-sized theropods such as the Dinosaur Provincial Park fauna (Campanian faunal stage of the Late Cretaceous), lacked medium-sized carnivorous dinosaurs in the size range from 100 kilograms to 1,000 kilograms.
In contrast, modern mammalian communities such as that which exists on the savannah of Kruger National Park in South Africa have predators in a range of sizes, small ones such as mongooses, medium-sized species such as wild dogs as well as mega-carnivores such as leopards and lions. Each meat-eating species is able to exploit a food resource (prey animals). The distinctive biology of the Dinosauria wherein, all predators hatched from eggs so started out as tiny in size perhaps less than ten kilogrammes for even the largest tyrannosaurids, may have led to a fundamental shift in predator community dynamics.
Rapidly growing juveniles and sub-adults of the larger species could have out-competed the fully grown medium-sized carnivores (mesocarnivores).
Gorgosaurus libratus – An Apex Predator of the Dinosaur Park Formation
Did juvenile and sub-adult tyrannosaurids such as Gorgosaurus and Daspletosaurus out-compete mesocarnivores?Picture credit: Everything Dinosaur.
Picture credit: Everything Dinosaur
Lead author PhD student Katlin Schroeder (University of New Mexico), explained: “Dinosaur communities were like shopping malls on a Saturday afternoon — jam-packed with teenagers. They made up a significant portion of the individuals in a species and would have had a very real impact on the resources available in communities.”
Compiling Physiological Data on Dinosaur Dominated Ecosystems
The researchers compiled physiological and fossil data on more than 550 different dinosaur species from 43 different dinosaur dominated ecosystems. They found that there was an absence of mesocarnivores. The scientists concluded that it was the teenage megatheropods that created and filled this gap in the community. After dividing this 100 to 1,000 kilogram gap into different weight categories, they found that juvenile megatheropods made up more than 50% of the total dinosaur biomass in every weight class. This is like a boxer destined to be the heavyweight champion dominating the bantam, lightweight and middleweight classes during their rise to the top.
Abelisaurids Also Drove out Mesocarnivores
A typical large theropod dinosaur. Like the Tyrannosauridae, abelisaurs were the megatheropods in a number of dinosaur communities that lacked mesocarnivores. Picture credit: Everything Dinosaur.
Picture credit: Everything Dinosaur
Driving Out the Medium-sized Meat-eaters
Although herbivorous dinosaurs were found in a range of different body sizes, including medium-sized ones, the team concluded that when it came to the meat-eaters, the way in which large carnivorous dinosaurs grew was an important factor that helped shape dinosaur community structure and diversity.
Co-author of the study, Kate Lyons (Assistant Professor of Biological Sciences at the University of Nebraska-Lincoln), added that the research:
“Essentially says that megatheropods were consuming 50% or more of the energy available to dinosaurs at a respective body size, leaving very little for other species to consume. If they were consuming the majority of the energy at that body size, then they were going to be outcompeting anything else that might try to feed at that size, as well.”
A Difference in Jurassic and Cretaceous Dinosaur Communities
It was noted that there was a subtle difference between dinosaur communities from the Jurassic with those from the Cretaceous. Generally, there were smaller gaps in the size range of carnivorous dinosaurs during the Jurassic when compared to the size gap seen in later communities dating from the Cretaceous.
Katlin Schroeder postulated that this difference came about because:
“Jurassic megatheropods don’t change as much, the teenagers are more like the adults, which leaves more room in the community for multiple families of megatheropods as well as some smaller carnivores. The Cretaceous, on the other hand, is completely dominated by tyrannosaurs and abelisaurs, which change a lot as they grow.”
Jurassic Ecosystems
Torvosaurus gurneyi a top predator of Portugal from the Late Jurassic but there were also mesocarnivores in this ecosystem too such as Lourinhanosaurus, Ceratosaurus and Lusovenator.
Picture credit: Sergey Krasovskiy
The scientific paper: “The influence of juvenile dinosaurs on community structure and diversity” by Katlin Schroeder, S. Kathleen Lyons and Felisa A. Smith published in Science.
