A remarkable new sauropod dinosaur discovery is the focus of a recent paper published in the open access journal “PeerJ”.  The study introduces Bicharracosaurus dionidei, fossils of which herald from Upper Jurassic deposits from the Cañadón Calcáreo Formation of southern Argentina. This research captures attention. Not only does it describe a new species, but it also reshapes how scientists understand sauropod evolution in the Southern Hemisphere.

Sauropod Evolution

Much of what we know about sauropod evolution comes from studying fossils from the Northern Hemisphere. Less is known about sauropod evolution and radiation in the Southern Hemisphere. Hence, the discovery of a new sauropod species from southern Argentina is especially significant. In March 2001, farmer Dionide Mesa reported the discovery of some dinosaur vertebrae.  Fieldwork commenced the following year and by 2011 much of the fossil material had been removed.  However, more neck bones (cervical vertebrae) were excavated in 2018.

In total, more than thirty vertebrae, ribs and parts of the pelvis were found.  The material dates from the Upper Jurassic (Oxfordian to Kimmeridgian faunal stages).  Palaeontologists estimate this sauropod fossil material to be approximately 155 million years old.  The fossils probably represent a mature, adult specimen.  Estimates suggest that this dinosaur measured between fifteen to twenty metres in length.

Bicharracosaurus dionidei life reconstruction and scale drawing. Picture credit: Everything Dinosaur (AI assisted).

Picture credit: Everything Dinosaur (AI assisted)

Bicharracosaurus dionidei

What makes Bicharracosaurus dionidei particularly interesting is its unusual mix of sauropod traits. For example, the dorsal vertebrae are similar to the dorsal vertebrae of diplodocids.  However, some fossil bones are reminiscent of the bones of brachiosaurids such as the giant Giraffatitan brancai from the Late Jurassic of Tanzania.  This combination of autapomorphies is unexpected.  Consequently, the research team conducted a detailed phylogenetic analysis.  The results were inconclusive. The overall evidence supports a position of Bicharracosaurus within Macronaria with several analyses and diagnostic characters suggesting brachiosaurid affinities. Bicharracosaurus sits in a somewhat uncertain evolutionary position.

Intriguingly, if the brachiosaurid affinity proves to be correct, then Bicharracosaurus dionidei would be the first member of the Brachiosauridae from the Jurassic of South America.

A Sauropod Puzzle

Several sauropods have been described from fossil material associated with the Cañadón Calcáreo Formation.  For instance, Tehuelchesaurus benitezii which was named and described in 1999 (Rich et al). Tehuelchesaurus is thought to be a macronarian like Bicharracosaurus.  However, whilst Bicharracosaurus shows a combination of sauropod characteristics (diplodocid and brachiosaurid), Tehuelchesaurus is thought to be a member of the Camarasauridae family.

Despite some similarities between Bicharracosaurus and Tehuelchesaurus benitezii fossil material, only in some of the phylogenetic results were these two species recovered as closely related. Whereas in most analyses, Tehuelchesaurus formed a clade with Janenschia robusta, a sauropod from the Late Jurassic of Tanzania. In addition, several diagnostic characters of Bicharracosaurus are absent in Tehuelchesaurus and vice versa. The results also show that other putative macronarian taxa have incongruent positions depending on the dataset.  These inconsistencies are hindering understanding of the early evolution of the Macronaria.

A model of a typical member of the Brachiosauridae family. The Wild Safari Prehistoric World Brachiosaurus dinosaur model. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

The image (above) shows a model of a Brachiosaurus.

For models and replicas of sauropods, including brachiosaurids, diplodocids and other dinosaurs: Dinosaur Models and Dinosaur Toys.

The Naming of Bicharracosaurus dionidei

The taxonomic affinity of this new dinosaur species remains uncertain. It demonstrates that early macronarian evolution was more complicated than previously thought. Until now, scientists relied heavily on fossils from North America and Europe. In contrast, southern continents such as South America and Africa were underrepresented. As a result, evolutionary models may have been biased. Thanks to this newly described sauropod, palaeontologists have the opportunity to test existing ideas and refine theories.  However, it does suggest that sauropod diversity in Gondwana was greater than expected.

The genus name comes from a Spanish term meaning “big animal”. Meanwhile, the species name honours Dionide Mesa, in recognition of the original fossil discovery.

Overall, this study provides fresh insight into one of the most iconic dinosaur groups. It highlights the importance of Southern Hemisphere sauropod fossils. At the same time, it reveals how much there is still to learn. Each new discovery has the potential to challenge established ideas. In this case, Bicharracosaurus dionidei offers a fascinating glimpse into the complex early evolution of macronarian sauropods.

The scientific paper: “Bicharracosaurus dionidei, gen. et sp. nov., a new macronarian (Dinosauria, Sauropoda) from the Late Jurassic Cañadón Calcáreo Formation of Argentina and the problematic early evolution of macronarians” by Alexandra Reutter​, José Luis Carballido, Guillermo José Windholz, Diego Pol and Oliver W.M. Rauhut published in PeerJ.

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The discovery of a new titanosaur from Morocco is helping palaeontologists rethink dinosaur diversity at the end of the Mesozoic. Indeed, researchers conclude that Maastrichtian dinosaur diversity is underestimated.  Meet Phosphatotitan khouribgaensis the first definitive titanosaur described from the late Maastrichtian phosphates of Morocco. This exciting discovery provides fresh insights into African dinosaur faunas just before the mass extinction event.

A life reconstruction of the Late Cretaceous Moroccan titanosaur Phosphatotitan khouribgaensis. Picture credit: Everything Dinosaur (AI assisted).

Picture credit: Everything Dinosaur (AI assisted)

Learning About Late Cretaceous African Dinosaurs

The last few million years of the Cretaceous (Maastrichtian faunal stage), saw the final diversification of the Dinosauria prior to the K/Pg extinction event. Discussions of end-Cretaceous dinosaur diversity have focused on well-sampled faunas from Laurasia; far less is known about dinosaurian faunas of the Southern Hemisphere, especially Africa. Subsequently, African dinosaur faunas remain poorly understood.

Fortunately, the Maastrichtian-aged phosphate deposits of Morocco offer a rare window into this ancient palaeoecosystem. The fossils are found in the Khouribga Province (Sidi Chennane locality). They have yielded a variety of dinosaur fossils.  For example, abelisaurids and lambeosaurines.  Titanosaur fossils have been discovered, but no taxon had been erected.  However, the research team which included Dr Nicholas Longrich (University of Bath) were confident enough to describe a new species. Although incomplete, the remains are scientifically significant. The researchers identified dorsal, sacral, and caudal vertebrae, along with parts of the pelvis.  Importantly, the remains although fragmentary, preserve enough anatomical detail to confirm a new genus and species.

To learn more about the remarkable dinosaur biota associated with the Moroccan Maastrichtian phosphate deposits.

To read about Chenanisaurus barbaricus, a giant abelisaurid from North Africa: The Last African Dinosaur?

Two new abelisaurid theropods described: Two Abelisaurs Described from Fragmentary Remains.

Minqaria bata a new duck-billed dinosaur from the Late Cretaceous of Morocco: New Pony-sized Moroccan Lambeosaurine Dinosaur.

Links to South American Giants

Intriguingly, Phosphatotitan shows anatomical similarities with South American titanosaurs. In particular, it shares features with members of the Lognkosauria, a group that includes the enormous, Early Cretaceous Patagotitan (P. mayorum). For example, it possessed short dorsal and caudal centra, expanded dorsal and caudal neural spines, and a broad pubis. This new species differs from titanosaurs described from the Cretaceous of Africa and Europe.

This connection likely dates back to a time before Africa and South America fully separated. Around 100 million years ago, these landmasses split as the South Atlantic Ocean opened. Therefore, Phosphatotitan provides evidence of ancient biogeographic links across Gondwana.  The fossilised bones demonstrate that Phosphatotitan was much smaller than Patagotitan and other South American giants.  Scientists estimate that Phosphatotitan weighed between 3.5 and 4 tonnes. In contrast, Patagotitan is estimated to have weighed around 60 tonnes.

Sue from Everything Dinosaur poses in front of the colossal Patagotitan skeleton which is being exhibited at the Natural History Museum (London). The recently described Phosphatotitan khouribgaensis from the Late Cretaceous of Morocco could be closely related. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Why was Phosphatotitan khouribgaensis Small?

Despite its titanosaurian heritage and its close taxonomic relationship with Patagotitan, Phosphatotitan was surprisingly modest in size.  Body mass estimates of between three and a half to four tonnes have been proposed.  It was much smaller than most of its South American relatives. Its small size relative to other Lognkosauria suggests a lineage selected for small size. This could be a result of island dwarfism.  During the latest Cretaceous rising sea levels may have isolated parts of Morocco.  Consequently, the smaller landmasses and their limited resources could have favoured smaller dinosaurs.

Alternatively, environmental pressures may have played a key role. In some ecosystems, smaller herbivores outcompete larger ones. This pattern appears in South America, where smaller titanosaurs became more common. Similarly, Egyptian titanosaurs also tend to be small-bodied.  Therefore, Phosphatotitan may reflect a broader trend towards smaller sauropods in certain Late Cretaceous ecosystems.

Phosphatotitan khouribgaensis scale drawing. This titanosaur is thought to weigh around four tonnes and was around nine to ten metres long. Picture credit: Everything Dinosaur (AI assisted).

Picture credit: Everything Dinosaur (AI assisted)

Dinosaur Diversity in the Late Cretaceous May Have Been Underestimated

The discovery of Phosphatotitan khouribgaensis highlights the complexity of Late Cretaceous dinosaur dominated ecosystems. As continents drifted apart, dinosaur populations became increasingly isolated. This isolation led to high levels of endemism. At the same time, occasional dispersal events may have allowed some species to spread between landmasses. Consequently, dinosaur faunas in Gondwana were both diverse and regionally distinct.

The close relationships of Morocco’s titanosaurs and abelisaurids to South American species may reflect a wide distribution of these clades prior to the opening of the South Atlantic and the separation of Africa and South America around a hundred million years ago.  The high endemism seen in both the Northern and Southern Hemispheres suggests that Maastrichtian dinosaur diversity is underestimated.

The scientific paper: “A Titanosaurian Sauropod with South American Affinities (Lognkosauria: Argentinosauridae) from the Late Maastrichtian of Morocco and Evidence for Dinosaur Endemism in Africa” by Nicholas R. Longrich, Agustín Pérez-Moreno, Verónica Díez Díaz, Xabier Pereda-Suberbiola, Nathalie Bardet and Nour-Eddine Jalil published in Diversity.

The award-winning Everything Dinosaur website: Scientifically Accurate Models of Dinosaurs.

An international team of researchers have uncovered evidence that ancient octopuses were once giant, apex predators.  A study involving scientists from Japan and Germany suggests these early cephalopods were at the top of the food chain during the Cretaceous. A Cretaceous giant octopus preying on mosasaurs, plesiosaurs and other vertebrates is a frightening prospect.

The study was published in the journal “Science” earlier this month.  The largest living octopus is the Giant Pacific Octopus (Enteroctopus dofleini).  Its arm span can exceed six metres. However, the octopods revealed in this new research could have reached lengths exceeding nineteen metres (based on mantle size).  Octopi are regarded as highly intelligent and capable hunters.  Subsequently, much larger animals would have been formidable predators and probably competed with marine vertebrates.

Wear on Fossilised Jaws

Octopi and their close relatives have soft bodies.  As a result, they rarely fossilise and the fossil record of octopi is extremely sparse. This makes their evolutionary history difficult to study. For example, we recently published an article that re-examined a famous specimen from the Mazon Creek Lagerstätte.  For years, scientists believed this fossil represented an early octopus named Pohlsepia mazonensis.  However, newly published research revealed evidence of jaws.  Consequently, the fossil most probably represents a decaying nautiloid.

To read more about this research: Oldest Octopus Fossil is Not an Octopus Fossil.

Ironically, it is analysis of super-sized fossilised jaws that has led the researchers to conclude that giant octopi were apex predators in Cretaceous marine environments. These feeding structures preserve far more readily than soft tissues. These jaws, sometimes referred to as beaks, are made of chitin.  It has a greater fossilisation potential than soft tissue.

Using high-resolution grinding tomography and an artificial intelligence model, the team found fossil jaws hidden inside rock samples from Cretaceous deposits spanning 100 to 72 million years ago. These fossils, found in Japan and Vancouver Island, had been well preserved in calm seafloor sediments, retaining fine wear marks that reveal how these animals fed.

A life reconstruction of the Cretaceous giant octopus. Picture credit: Yohei Utsuki, Department of Earth and Planetary Sciences, Hokkaido University.

Picture credit: Yohei Utsuki, Department of Earth and Planetary Sciences, Hokkaido University

Giant Cephalopod Predators of Cretaceous Marine Environments

The fossil jaws have been assigned to two species, following a revision of known Cretaceous specimens.  The two species are:

• • Nanaimoteuthis jeletzkyi
  • Nanaimoteuthis haggarti

The remains have been placed in an extinct group of finned octopi known as Cirrata. By analysing jaw size, shape and wear the team reconstructed their feeding habits. Furthermore, the wear patterns revealed powerful biting forces. The researchers concluded that these animals actively hunted and crushed hard prey. Therefore, they were not passive feeders. Instead, they were powerful predators in the North Pacific Ocean during the age of dinosaurs.

Co-author of the study, Professor Yasuhiro Iba (Hokkaido University) commented:

“Our findings suggest that the earliest octopuses were gigantic predators that occupied the top of the marine food chain in the Cretaceous. Based on exceptionally well-preserved fossil jaws, we show that these animals reached total lengths of up to nearly twenty metres, which may have surpassed the size of large marine reptiles of the same age.”

Evidence of Feeding on Hard Body Parts (Shells and Skeletons)

Careful analysis of the jaws revealed extensive wear.  For example, the team identified scratches, chips and cracking.  These features indicate repeated, forceful biting.  Furthermore, the tips of the beaks were extensively damaged.  Up to ten percent of the jaw tip had been worn away.  The researchers concluded that this damage was not caused by transport induced abrasion.  For example, the remains of the jaws being rolled by water currents along the seabed. The level of damage exceeds that seen in modern cephalopod beaks. As a result, the team inferred an aggressive feeding strategy. Moreover, it suggests these cephalopods regularly tackled hard-bodied prey.

The scientists suggest that cephalopods may have been apex predators in the North Pacific Ocean during the Cretaceous. Picture credit: Everything Dinosaur (AI assisted).

Picture credit: Everything Dinosaur (AI assisted)

The picture (above) shows a hypothesised relationship between predatory vertebrates and the giant Cretaceous octopus.  The mosasaur, plesiosaur and the Xiphactinus figure are from the CollectA range of figures.  Whereas the Cretoxyrhina illustration is based on the PNSO model.

To view the CollectA Prehistoric Life Age of Dinosaurs range: CollectA Prehistoric Life Models.

To view the CollectA Deluxe prehistoric animal models: CollectA Deluxe Prehistoric Animal Figures.

PNSO prehistoric animal figures: PNSO Age of Dinosaurs.

An Intelligent Giant Cretaceous Octopus

Intriguingly, the fossils reveal uneven wear on the jaws.  One side shows more damage than the other side.  This suggests that these octopi might have favoured one side of the jaw when feeding. Asymmetric wear patterns indicate lateralised behaviour, the animal clearly favouring one side of the jaw over the other. Subsequently, the researchers conclude that these octopi were intelligent. In extant animals, lateralised behaviour is linked to advanced brain function.  Therefore, a giant Cretaceous octopus may have displayed complex behaviours.  Perhaps, they were smart enough to catch a plesiosaur.

The Kraken

The mythical Kraken was feared by sailors for centuries. Whilst some extant cephalopods such as the colossal squid (Mesonychoteuthis hamiltoni) can reach lengths of more than ten metres, these Cretaceous giants might have been twice as long.  As a result, during the Cretaceous some invertebrates may have occupied apex predator roles.  This new study proposes that giant octopi may have competed directly with large vertebrate predators. It makes them a rare example of an invertebrate successfully competing with large vertebrate predators.  Furthermore, it provides a tantalising insight into Cretaceous marine environments.

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

The scientific paper: “Earliest octopuses were giant top predators in Cretaceous oceans” by Shin Ikegami, Jörg Mutterlose, Kanta Sugiura, Yusuke Takeda, Mehmet Oguz Derin, Aya Kubota, Kazuki Tainaka, Takahiro Harada, Harufumi Nishida, and Yasuhiro Iba published in the journal Science.

The Early Cretaceous ornithopod Lanzhousaurus magnidens described in 2005 (You, Ji and Li) has remarkable dentition. It had some of the largest plant-eating teeth known to science. However, unlike its relatives, it had relatively few teeth in its metre-long jaws.  This unusual Chinese dinosaur puzzles palaeontologists.  Why did L. magnidens evolve such enormous teeth?

Team members research and write fact sheets.  These data sheets are sent out with sales of prehistoric animal figures. A Lanzhousaurus fact sheet had been prepared in time for the arrival of the new PNSO Lanqi the Lanzhousaurus model.  Our fact sheet on Lanzhousaurus highlights the unusual dentition.

PNSO Lanqi the Lanzhousaurus (L. magnidens) dinosaur model which is new for 2026. This ornithopod was formally named and described in 2005.

The image (above) is that of the new PNSO Lanzhousaurus model.  Everything Dinosaur team members have researched this ornithopod as they prepare to receive the models into stock.

To view the range of PNSO models available to Everything Dinosaur: PNSO Prehistoric Animal Models.

A Curious Ornithopod from Gansu Province

Lanzhousaurus fossils were unearthed in Gansu Province, north-western China. During the Early Cretaceous, ornithopod dinosaurs were diversifying rapidly. Unlike its near relatives, this herbivore followed a different evolutionary path.  The fossilised teeth of Lanzhousaurus are robust and built to withstand heavy stresses.  In addition, they are huge, with some examples over 10 cm long. Moreover, they had far fewer teeth compared to iguanodontids and advanced hadrosaurids. This suggests a different feeding strategy. Instead of grinding plant material with many small teeth, Lanzhousaurus magnidens likely relied on powerful biting.

An illustration of Lanzhousaurus. It will be used in a free fact sheet that will be sent out with the new PNSO Lanzhousaurus dinosaur model. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Small numbers of large teeth in the jaw suggest that this plant-eating dinosaur may have processed food by crushing and slicing. Large teeth usually indicate strong bite forces.

This evolutionary approach offers several advantages. For instance, exceptionally large teeth:

• Resist wear under heavy loads.
• Handle tougher vegetation.
• Require less complex replacement systems.

Perhaps this dinosaur functioned like a heavy-duty plant processor.  Our fact sheet discusses the strange dentition. The palaeoenvironment of Early Cretaceous China included fibrous plants. For example, there were numerous species of conifers and tough cycads. Consequently, Lanzhousaurus magnidens may have specialised in eating these harder food resources. Its teeth would have been ideal for stripping branches, crushing plant stems and breaking down fibrous plants.

In contrast, later hadrosaurids evolved dental batteries to finely grind plant material.  These dental batteries were extremely efficient at processing vegetation.

Duck-billed dinosaur on display. An Edmontosaurus a member of the Saurolophinae subfamily of the Hadrosauridae with its very efficient jaws and dental battery. Picture credit: Everything Dinosaur.

Picture credit: Everything Dinosaur

Why No Dental Battery?

Dental batteries evolved later in hadrosaurid dinosaurs. These systems required complex jaw mechanics and continuous tooth replacement. However, Lanzhousaurus magnidens represents an earlier stage in evolution. Its dentition had not yet developed into a full battery system. Instead, its jaw morphology demonstrates a different solution to herbivory. Evolution does not follow a single path. In this case, large teeth replaced the need for many smaller ones.

Furthermore, Lanzhousaurus may have occupied a unique ecological niche. By feeding on tougher plants, it avoided direct competition with other herbivores. A scientific concept known as niche-partitioning. This type of niche partitioning is common in dinosaur ecosystems. It allows multiple species to coexist in the same environment. Therefore, its unusual teeth may reflect both diet and competition.

Ultimately, Lanzhousaurus magnidens represents an evolutionary experiment. Ornithopods explored several feeding strategies before dental batteries became dominant.

Later hadrosaurids proved highly successful with their grinding teeth. However, Lanzhousaurus magnidens shows that alternative strategies also worked.  Perhaps more fossils of ornithopods with bizarre, super-sized teeth will be found in the future.

Mike from Everything Dinosaur commented:

“We enjoyed researching Lanzhousaurus.  Its unusual adaptations make it stand out amongst the Ornithopoda.  Moreover, it gave us the opportunity to discuss the unusual dentition in our free fact sheet.”

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