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Ciao, ma il podcast di Spotify lo riprenderai?
RispondiEliminaNo, mi trovo meglio con YouTube.
EliminaHello. What is your opinion on Bahariasaurus ingens?
RispondiEliminaWe need new fossils.
EliminaYeah. Unfortunately the syntypes and other reffered material was lost. Also, do you believe that the material reffered to Deltadromeus agilis by Sereno (1996) and later Ibrahim (2020) belongs to Delta?
EliminaIf you mean the Baharjia material of Stromer (1934), who knows? It might be Bahariasaurus and Deltadromeus might be Bahariasaurus too... or they might be closely related yet distinct... in brief, we need more and better preserved specimens before assessing anything.
EliminaInterestingly Deltadromeus overlaps with Bahariasaurus ingens specimen IPHG 1912 VIII 62.
EliminaBy the way, what taxa do you consider to be Megaraptoran?
EliminaIPHG 1912 VIII 62 includes a pubis fragment and some caudal vertebrae. The referral of such material to Bahariasaurus is tentative (although likely).
EliminaMegaraptor and its closest relatives are megaraptorans.
62 also has three dorsals (longest theropod dorsals in fact), which overlap with two of Bahariasaurus syntypes (47 and 48). Is it possible that Bahariasaurus is a non-Megaraptoran Tyrannosauroid?
EliminaMegaraptor and it closest relatives includes Megaraptor, Murusraptor, Aerosteon, Tratayenia, Maip, Orkoraptor, Australovenator, Rapator, Aoniraptor, "A." sibiricus, "A." "robustus", Phuwiangvenator, Fukuiraptor, Vayuraptor and maybe also Siats, Chilantaisaurus, Aniksosaurus, Bahariasaurus, Datanglong and Vectaerovenator. There are some unnamed taxa too. Are there any other taxa that I forgot about?
I concur with Motta et al. 2016 that (some?) of the Bahariasaurus dorsals of Stromer (1934) might instead be caudals.
RispondiEliminaBahariasaurus and its potential relatives might alternatively ceratosaurians or non-tyrannosauroid coelurosaurs. Not all the taxa you listed could be megaraptorans. We need more data, because it's easy to move some of them in different positions in Theropoda just scoring a few characters or removing a few taxa from analyses.
About Bahariasaurus dorsals being caudals: https://twitter.com/Manu_MB13/status/1584865535166099456
EliminaI doubt that Bahariasaurus is a Ceratosaur, since it has for example sacral pleurocoels.
Yeah, some taxa that I mentioned can easily be not Megaraptoran, like Vectaerovenator or Bahariasaurus.
By the way, the tweet is not by me
EliminaMy pet hypothesis is that bahariasaurids are coelurosaurs, but in some iteration of my analyses they turn among ceratosaurs. The presence of sacral pleurocoels is not necessarily against a ceratosaur placement, since it might be a bahariasaurid novelty among them (and this feature is quite homoplastic in neotheropods). Shallow pleurocoel depressions are also in some ceratosaurs, so I don't see the problem in such feature. The twitter account you mentioned states that those vertebrae cannot be caudals because they lack a ventral sulcus: yet such absence is also in Aoniraptor, some megaraptorans and some carcharodontosaurids, so it is not against their interpretation as megaraptoran-related caudals. The twitter account is also wrong in stating that those vertebrae lack chevron facet, instead they are very prominent in Stormer's (1934) vertebra 14 of Table II. So, I see no reason for rejecting the hypothesis that those are caudals instead of dorsals.
EliminaWhat other taxa do you believe to be Bahariasaurid?
EliminaAlongside sacral pleurocoels, there is also the coracoid, which is short and triangular (like that of Therizinosaurus or Dilong). The lack of ventral groove is mentioned since the Bahariasaurus caudal 62d has a ventral groove.
Vert 14 in Plate II is this one?
https://twitter.com/Manu_MB13/status/1657489525449318400
Also, the Bahariasaurus verts 62a-c aren't similar in proportions to the anterior caudal 62d. a-c are 50-80% longer than tall while d is only ~20% longer than tall.
Interestingly, Bagaraatan caudals are quite similar to those of Bahariasaurus
Eliminahttps://twitter.com/Manu_MB13/status/1563139064261332992
Bagaraatan tail is tyrannosauroid-like (which can also include bahariasaurs).
EliminaAlso, what's your opinion on the phylogenetic position of Chilantaisaurus in the phylogenetic tree of Maip description paper?
EliminaWeak result, poorly supported.
EliminaIs Datanglong a Megaraptoran?
Elimina