A Tyrannosaur-like Allosaur

[Chad]

https://www.theguardian.com/science/2016/jul/13/meet-gualicho-shinyae-the-puny-armed-distant-relative-of-t-rex

[EarthboundEiniosaurus]

This is absolutely incredible, this and the Burmese amber wings have made this year even more amazing, I can't wait to see what else this year has to offer

Thanks,

EarthboundEiniosaurus

[Yutyrannus]

Here's the paper:
http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0157793

Apparently it's a neovenatorid.

[Halichoeres]

The etymology notes are hilariously understated: "chosen to reflect the difficult circumstances surrounding the discovery." Also, I love PLoS ONE.

[Sim]

Here's the paper:
http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0157793

Apparently it's a neovenatorid.

Thanks for the link to the paper.  I wonder how accurately it can be classified though, given what parts it is known from.  The paper also finds megaraptorans to be neovenatorids and it's known the classification of megaraptorans isn't agreed upon.  If I'm understanding it right, the paper also finds Deltadromeus to be a neovenatorid allosauroid?  Less than a month ago, another fragmentary theropod naming paper (the Aoniraptor/Taurovenator one) found megaraptorans to be tyrannosauroids and Deltadromeus to probably be a megaraptoran tyrannosauroid.  And about two months earlier, a paper on Elaphrosaurus found Deltadromeus to be a noasaurid ceratosaur.  So in about three months Deltadromeus has on separate occasions been found to be a ceratosaur, (probably) a tyrannosauroid and an allosauroid.  And within a more recent and shorter time period megaraptorans have on separate occasions been found to be tyrannosauroids and allosauroids.  What I find myself concluding is it seems no-one knows what these large, very incomplete theropods are.

Personally, I find the recent naming of many very fragmentary theropods not very impressive.  By the way, Andrea Cau has written a blog post where he explains why he thinks Gualicho could be the same animal as Aoniraptor.  Gualicho has been described as an allosauroid and Aoniraptor as a tyrannosauroid so if Gualicho and Aoniraptor are one and the same, what group does it belong to?  And Deltadromeus?  That's just one species that's been recently classified in three different groups!  Here's a link to the Andrea Cau blog post: http://theropoda.blogspot.co.uk/2016/07/nuovi-resti-di-aoniraptor-ehm-benvenuto.html

[Dinoguy2]

Here's the paper:
http://journals.plos.org/plosone/article?id=10.1371%2Fjournal.pone.0157793

Apparently it's a neovenatorid.

Thanks for the link to the paper.  I wonder how accurately it can be classified though, given what parts it is known from.  The paper also finds megaraptorans to be neovenatorids and it's known the classification of megaraptorans isn't agreed upon.  If I'm understanding it right, the paper also finds Deltadromeus to be a neovenatorid allosauroid?  Less than a month ago, another fragmentary theropod naming paper (the Aoniraptor/Taurovenator one) found megaraptorans to be tyrannosauroids and Deltadromeus to probably be a megaraptoran tyrannosauroid.  And about two months earlier, a paper on Elaphrosaurus found Deltadromeus to be a noasaurid ceratosaur.  So in about three months Deltadromeus has on separate occasions been found to be a ceratosaur, (probably) a tyrannosauroid and an allosauroid.  And within a more recent and shorter time period megaraptorans have on separate occasions been found to be tyrannosauroids and allosauroids.  What I find myself concluding is it seems no-one knows what these large, very incomplete theropods are.

I think this is more an effect of the fact that we still don't know what megaraptorans are. They might be tyrannosauroids, they might be allosauroids, they might be basal coelurosaurs, but they're pulling their relatives all around the tree in every different analysis.

Less than a month ago, another fragmentary theropod naming paper (the Aoniraptor/Taurovenator one)

Somebody pointed out that the diagnostic features of Aoniraptor are identical to those in Gualicho. So they're probably synonyms.

I think we can be pretty confident that Aoniraptor/Gualicho and Deltadromeus are both basal megaraptorans. Whatever Gualicho is, it provided the clues necessary to identify Deltadromeus, which is much less complete but shares so many key features they're practically identical as far as we can tell. Gualicho is exciting because it finally represents a sort of "more complete Deltadromeus". And Gualicho shows that it and Delta are allied to megaraptorans.

The questions now are: What the heck ARE megaraptorans, and is Neovenator related to them or not (the fact somebody chose to anchor a family name on that thing is really upping the confusion factor).

The fact that Deltadromeus has been bouncing around the theropod tree all these years turns out to be because it's part of this weirdo group with a mosaic of features characteristic of allosaurs and tyrannosaurs. And now, it turns out that the primitive members ALSO have features characteristic of ceratosaurs, which is why Delta has been found there lately - primitive megaraptorans are ceratosaur-like.

These things are like the "segnosaurs" of the 2010s

In the analysis of the modified Porfiri et al. [11] dataset, Gualicho was recovered near the base of Coelurosauria (Fig 14B), well removed from either didactyl tyrannosaurids, or the megaraptoran clade it was close to in the Carrano et al. [7] dataset. Surprisingly, however, our reanalysis following changes to the matrix found Neovenator as sister taxon to a clade of coelurosaurs plus Gualicho and megaraptorans rather than as a member of Allosauroidea. We did not find support for megaraptorans as members of Tyrannosauroidea as previously reported [11, 12] after rescoring a number of characters in those analyses (see S1 Text) and running all traits as unordered, although megaraptorans were found to be closer to tyrannosauroids than to the included carcharodontosaurids. The very different results of these two analyses are predicated on significant differences in both taxon- and character sampling, and only a more comprehensive analysis beyond the scope of this description can resolve the disagreement.

I'm curious to see where Andrea Cau finds it in his megamatrix. That should solve the character and taxon sampling issues.

[Derek.McManus]

Very interesting I look forward to learning more!

[Postosuchus84]

Gualicho is definitely significant for megraptoran and neovenatorid evolution. I look forward to additional studies.