Dr Suresh Singh

Mounted skeleton of Tyrannosaurus rex

Fossil partial skull of Albertosaurus sarcophagus

For #FossilFriday, in honor of the 120th naming of both species (tomorrow), the type specimens of Tyrannosaurus rex (at the Carnegie Museum) and Albertosaurus sarcophagus (@museumofnature)

Its discovery shed new light on the evolution of hyper-specialised, megapredatory tyrannosaurids 🦖 Lythronax captures the early evolution of the Tyrannosaurus-style predatory ecology ~20 million years before T. rex.

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Reinforced skulls would have allowed these predators to withstand the high biomechanical stresses incurred from inflicting powerful bites on large, robust, struggling prey. These were megapredators, specialised to take on large prey.

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The positioning of the eyes provided better depth perception, allowing Lythronax, Tyrannosaurus, and Tarbosaurus to properly focus on their prey at both long & short distances, also enabling them to precisely time their attack/bite for maximum impact.

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The skull is short & similarly reinforced to T. rex & its close Asian relative, #Tarbosaurus. Additionally, #Lythronax has eyes that face forward more so than other tyrannosaurids, bar #Tyrannosaurus & Tarbosaurus. These were active predators adapted for rough interactions with prey.

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While smaller than T. rex at upto 5-8 metres long, #Lythronax is still thought to have been a similarly formidable ‘big game hunter’ of its time. Indeed, its skull anatomy appears to show its close evolutionary relationship & ecological similarity to T. rex.

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A mounted reconstructed skeleton of the tyrannosaurid, Lythronax argestes, and its skull on display at the Utah Museum of Natural History in Salt Lake City, Utah, USA.

Here’s a snapshot of the basal tyrannosaurid, Lythronax argestes for this #FossilFriday. It lived ~80 Ma, making it a much older cousin of the famous, #Tyrannosaurus rex 🦖- Discovered in Southern Utah 🇺🇸, its name means "gore king from the southwest."

#Paleontology #Science #Dinosaurs

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Figure 1 from the paper, showing the locality location and geology.

New paper by Degrange et al. reports a new phorusrhacid (AKA #TerrorBird) from La Venta, Colombia 🇨🇴 - this is the 2nd terror bird from the site, suggesting perhaps some niche partitioning between these giant avian predators ⬇️

#Paleontology #Science

www.mdpi.com/1424-2818/17...

An ornithischian-theropod ichnoassemblage from the Norian-Rhaetian transition of Poland In this paper, we describe a dinosaur track assemblage from an Upper Triassic fluvial succession at the Lisowice-Lipie Śląskie site in Silesia, southe…

New paper by Niedźwiedzki et al. reports ichnofossil 👣🐾 assemblage apparently made by ornithischian & megatheropod #dinosaurs in the latest #Triassic. Lots of interesting new info on the early rise of dinosaurs coming out of Poland! 🇵🇱 ⬇️

#Paleontology #Science

www.sciencedirect.com/science/arti...

This shows the challenges of trying to reconstruct the ecology of long extinct creatures! Whatever it did, Ceratosaurus was a highly successful predator - its fossils are reported from North & South America, Africa & Europe, and span ~155 - 143 Ma across the Late Jurassic.

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However, we have to be careful as while these palaeoenvironments could reflect the actual habitat preferences of Ceratosaurus, it could just be where their remains were preferentially preserved - such watery environments have better #fossil preservation potential.

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However, the long, blade-like teeth of Ceratosaurus have also been suggested as adaptations for feeding on fish 🐟 Further evidence for piscivorous diets comes from the palaeoenvironments these theropods are often found in - wetter environments with large bodies of water.

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Such klepto-parasitism is quite common among diverse predator communities - just think of mammalian predators of the African savannahs today. Larger carnivores will take their chances to steal a meal from smaller predators - much easier than hunting for themselves!

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However, these teeth were also more fragile, and ill-suited for biting into bone. Consequently, Ceratosaurus likely fed on the fleshiest parts of its prey, with its blade-like teeth helping to quickly slice off strips of meat before larger predators arrived to steal the kill.

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Ceratosaurus is a more primitive #theropod than its Morrison competitors (e.g., #Allosaurus & #Torvosaurus) but appears to have found a distinct niche within the carnivore guild. Its teeth were relatively long & thin, making them extremely effective at slicing off flesh 🔪

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A skull reconstruction of Ceratosaurus nasicornis on display at the Brigham Young University Museum in Provo, Utah, USA. This skull was created using two fragmentary skulls in the museum’s fossil collections.

Presenting the skull of #Ceratosaurus nasicornis for this #FossilFriday. This medium-sized (up to ~5.5 metres long), theropod dinosaur 🦖 was one of the rarer & perhaps most enigmatic predators of the #Jurassic Morrison Formation in the southwestern US 🇺🇸

#Paleontology #Science

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Ecological restoration map of the tritylodont, Polistodon chuannanensis. Artwork supplied by the researchers, artist unknown I’m afraid.

Here’s a news article on the paper (with some nice artwork of one of the mammaliamorph taxa):
www.globaltimes.cn/page/202509/...

Convergent evolution of diverse jaw joints in mammaliamorphs - Nature High-resolution computed tomography is used to reconstruct and analyse fossils of the herbivorous tritylodontid Polistodon and a newly named morganucodontid species called Camurocondylus, providing key insights into the evolution of the mammalian jaw joint.

New paper by Mao et al. describes divergent approaches to evolving a secondary jaw joint in two #Jurassic mammaliamorphs from China 🇨🇳 - Seems there was quite a bit of morphological experimentation in such proto- #mammals! ⬇️

#Paleontology #Science

www.nature.com/articles/s41...

Oldest winged insects: first Megasecoptera from the early Carboniferous (Serpukhovian) of Argentina Mississippian insect records are extremely rare. Formally, winged insects occur only at two sites from the Serpukhovian: Delitzsch in Germany, with one species of Palaeodictyoptera; and Guandacol 1 i...

New paper by Petrulevičius & Gutiérrez presents the oldest winged insects 🦟 from Argentina 🇦🇷 dating back to the early #Carboniferous - More insight into the early diversification of animal life & ecosystems on land. ⬇️

#Paleontology #Science

onlinelibrary.wiley.com/doi/10.1111/...

Latest Cretaceous megaraptorid theropod dinosaur sheds light on megaraptoran evolution and palaeobiology - Nature Communications Megaraptoran theropod dinosaur anatomy and evolution is unclear due to the fragmentary nature of most available fossils. Here the authors report a well-preserved, late surviving megaraptoran from Argentina that clarifies our understanding of the morphology of this group and potentially provides insights into its diet and feeding strategies.

New megaraptorid #theropod, Joaquinraptor casali, described by Ibiricu et al. from a partial skeleton discovered Argentina 🇦🇷 - nice to have some more skull material from one of these enigmatic predators!

#Dinosaur #Paleontology #Science

www.nature.com/articles/s41...

Dinosaur extinction can explain continental facies shifts at the Cretaceous-Paleogene boundary - Communications Earth & Environment Dinosaurs promoted open habitats in the Late Cretaceous, and their extinction could have led to a radical reorganization of the landscape and ecosystem structure at the beginning of the Paleogene, acc...

Dinosaurs as ecosystem engineers!

Weaver, L.N., Tobin, T.S., Sprain, C.J. et al. Dinosaur extinction can explain continental facies shifts at the Cretaceous-Paleogene boundary. Commun Earth Environ 6, 712 (2025). doi.org/10.1038/s432...

This discovery is highlighted in the U-M Museum of Natural History. Although Beck's pivotal specimen isn't displayed, you can see this giant Archaeopteris trunk (UMMP 13837)--my favorite fossil in the gallery.

Mark Norell, Who Studied Link Between Dinosaurs and Birds, Dies at 68

New York Times obituary for one of New York’s greatest characters. RIP Mark, and you’d enjoy the Romanian palinka we’re toasting in your honor tonight!

www.nytimes.com/2025/09/13/s...

Multicolored CT model of a fossil cichlid skeleton. Image credit: Austin Babut (project technician).

Do you like cichlids? Fossils? Fossil cichlids? Would you like to study them as part of a graduate degree at the University of Michigan, joining an NSF-funded project? Get in touch.

Parareptile diversity encompassed semi aquatic & terrestrial forms. #Pareiasaurs were key terrestrial herbivores during the #Permian, being geographically widespread & taxonomically diverse. However they went extinct in the End-Permian mass extinction.

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It was thought that parareptiles were a separate tetrapod group from diapsids (e.g., lizards, crocodiles & birds) & synapsids (e.g., mammals), with turtles being the only living representatives of the group. However, growing phylogenetic evidence suggests that they are actually early diapsids.

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#Parareptiles are group of tetrapods that have puzzled paleontologists for quite a while. They were quite diverse during the #Permian & while they suffered through the Permo-Triassic mass extinction event, they survived & remained prominent within terrestrial faunas across the #Triassic.

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A photo of the front of the mounted skeleton of the pareiasaurus parareptile, Bradysaurus, on display at the Vienna Museum of Natural History. Shows the skull and front limbs.

Presenting a photo of the herbivorous parareptile, Bradysaurus for this #FossilFriday. This ancient animal lived ~265 Ma in the #Permian & was one of the larger terrestrial tetrapods of its time. Despite the name, it’s not a dinosaur, but a #pareiasaur #parareptile.

#paleontology #science

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September: Newtonsaurus identification | News and features | University of Bristol

Press release from @bristolpalaeo.bsky.social ⬇️

www.bristol.ac.uk/news/2025/se...

Re-assessment of a large archosaur dentary from the Late Triassic of South Wales, United Kingdom A large jaw of a predatory archosaur from the latest Triassic of South Wales, named Zanclodon cambrensis, has long intrigued vertebrate palaeontologis…

New theropod #dinosaur, Newtonsaurus cambrensis, described by Evans et al. from fossils collected >120 years ago in Wales 🏴󠁧󠁢󠁷󠁬󠁳󠁿 (UK). This large lower jaw fossil supports the evolution of large #theropods in the latest #Triassic 🦖

#paleontology #science

www.sciencedirect.com/science/arti...