SISTER FORMATIONS: MORRISON, LOURINHA AND TENDAGURU
Back in the Late Jurassic Period, North America, Europe and Africa were next door neighbors.
This is reflected in the similarity of the lithology, and fauna of the rocks. In North America, we have the Morrison Formation, in Europe we have the Lourinha Formation, and in Africa we have the Tendaguru Formation. All of these are contemporaneous or sister formations.
Stratigraphy
The Tendaguru Formation is approximately 177 m thick and broken up into five members: Lower Dinosaur Member (cross-bedded, fine-grained sand and siltstone w/interbedded clay), Nerinella Member (trough cross-bedded and massive sandstone indicating a tidal channels, sandbars and beaches),
Middle Dinosaur Member ( ripple, cross-bedded, fine-grained calcareous sandstone and siltstone and massive to crudely bedded siltstone and claystone indicating tidal flats and lagoons),
Indotrigonia Africana Member (calcite cemented sandstone, conglomerate, thin claystone, and siltstone with sandy limestone indicating tidal and deltaic channels),
and the Upper Dinosaur Member (ripple, cross-bedded, fine-grained sandstone and siltstone with interbedded claystone and micriitic carbonates indicating tidal flats).
The Lourinha Formation is about 200 to 1000 meters thick and is broken into about 5 members: Praia da Amoreira Member (massive mudstone with meter thick sandstone lenses and calcrete layers indicating a meandering river system),
the Porto Novo Member (cross-bedded sandstone indicating a deltaic system), the Praia Azul Member (marl and mudstone indicating brief marine transgression),
and the Santa Rita and Assenta Members (mudstone, caliche, shelly carbonates near the top indicating a landward side of a deltaic system) which are equivalent members from different basins.
The Morrison, as stated previously, is about 200 m thick and consists of 11 different members. I will not go into detail about them again but it should be noted that the formations are approximately the same thickness and made of primarily sand, silt and mudstone.
DINOSAURS
Now for the other fun part: the dinosaur fauna. There are some dinosaurs that are shared between two or all of the formations. These include Ceratosaurus nasicornis in the Morrison and a possible Ceratosaurus in the Tendaguru
and in the Lourinha, Torvosaurus tanneri in the Morrison, Torvosaurus gurneyi in the Lourinha, and a possible Torvosaurus species in the Tendaguru,
Allosaurus fragilis in the Morrison and Allosaurus europaeus in the Lourinha,
Dryosaurus altus in the Morrison and a possible Dryosaurus species in the Lourinha,
Miragaia longicollum in the Lourinha and possibly Miragaia longispinus in the Morrison. Though if that's true, the genus would be Alcovosaurus because that was named first.
And then there are the dinosaurs that were similar to each other in each formation. Filling in the niche or living alongside Dryosaurus was Dystalotosaurus of the Tendaguru,
Eudryosaurus in the Lourinha, and Nanosaurus in the Morrison.
There's Draconyx in the Lourinha and Camptosaurus in the Morrison as early iguanodonts.
Kentrosaurus in the Tendaguru, Dacentrurus in the Lourinha and Stegosaurus and Hesperosaurus in the Morrison are the main stegosaurs.
For ankylosaurs, there is Dracopelta in the Lourinha and Mymooropelta and Gargoyleosaurus in the Morrison.
Then there's Dicraeosaurus of the Tendaguru and Suuwassea of the Morrison.
Giraffatitan of the Tendaguru, Lusotitan of the Lourinha and Brachiosaurus of the Morrison all represent brachiosaurs.
Janenschia of the Tendaguru and Haplocanthosaurus of the Morrison represent early sauropods.
Tendaguria of the Tendaguru and Zby of the Lourinha are even earlier sauropods.
Torneiria of the Tendaguru and Deinheirosaurus of the Lourinha are the diplodocids that match up with the bagillion in the Morrison.
Lourinhasaurus is the camarasaurid representative of the Lourinha.
The Tendaguru and the Lourinha have early carcharadontosaurs in the forms of Veteruristisaurus and Lusovenator.
Lourinanosaurus is the European equivalent of Marshosaurus in the U.S.
And Elaphrosaurus of the Tendaguru is the small to medium-sized equivalent of Tanycoalgreus in the Morrison.
This was a ton of info so if you want it more broken down, message me! I am happy to walk you through it all! Enjoy your weekend!
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It Came From The Wastebasket #07: Carnosaur Carnage
Carnosauria was originally named in the 1920s as a grouping for all of the large-bodied theropod dinosaurs known at the time.
For much of the 20th century it was used as a general wastebasket taxon collecting together all big carnivorous forms – including allosaurids, carcharodontosaurids, megalosaurids, spinosaurids, ceratosaurids, abelisauroids, and tyrannosaurids – and for a while it even included a species that later turned out to be closer related to crocodiles than to dinosaurs.
From left to right: Asfaltovenator vialidadi, Torvosaurus tanneri, Giganotosaurus carolinii, & Baryonyx walkeri
But then cladistic analysis in the 1980s and 1990s revealed that some of these theropods weren't actually closely related at all. Carnosaurs weren't a natural lineage but instead were highly polyphyletic, with the physical similarities between them seeming to be more due to convergent evolution than direct shared ancestry.
Some carnosaurs were split off and reclassified as more "primitive" types of theropod, while the tyrannosaurs were placed much closer to birds with the coelurosaurs. The remaining "carnosaurs" were just the allosaurids, carcharodontosaurs, and their closest relatives, and some paleontologists now prefer to use the name Allosauroidea for this group to distance it from the previous wastebasket mess.
…But Carnosauria might not be done just yet.
The discovery of Asfaltovenator in 2019 complicated matters once again, with a mixture of anatomical features linking it to both the allosauroids and the megalosauroids (megalosaurids, spinosaurids, and their relatives) – suggesting that these two groups might actually have been closely related to each other in a single lineage after all.
This would potentially return Carnosauria back to something surprisingly close to its original definition, with the various megalosauroids now forming an evolutionary grade leading to the allosauroids.
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Megalosaurus bucklandii done in August for my friend's Birthday. This is the first non-avian dinosaur named (back in 1827). Since then, many specimens from Europe, North America and Africa have been attributed to it (among them Dilophosaurus, Carcharodontosaurus and even Plateosaurus), but today this species is limited to material from the Middle Jurassic of Oxfordshire (England). Initially, Megalosaurus was represented as a four-legged reptile, similar to a crocodile with the limbs of a large mammal. Now its appearance seems completely different. Despite its historical significance, Megalosaurus is still not well studied.
Paint Tool Sai 2.0, 2023.
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"The specimen was named Crimson, she's a fully grown Torvosaurus imperius residing in the woods of Washington. And.... she's too dangerous to be freed. She's been killing random hikers in the woods since 97' or 98, I don't even know anymore.... we just let them into the wild, and This happens! This happens and the boss doesn't give a shit"
Audio Log:Andrew Miller_06_17_2002
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