Wednesday, August 31, 2016

The Monster of Minden published at last

Those of you who frequented the Dinosaur Mailing List in the early 2000s might remember references to a supposedly gigantic German theropod- Das Monster von Minden.  After a few news stories, it was quickly forgotten until an abstract published last year (Rauhut et al., 2015) confirmed it as a new megalosaurid.  As of today it has been officially published and described as Wiehenvenator albati (Rauhut et al., 2016). 

Skull of Wiehenvenator albati holotype (WMN P27275, P27504, P27457, P27477, P27470, P27461, P27462 and P27466), scale equals 100 mm (after Rauhut et al., 2016).
The description is generally excellent, with multiple colored high resolution views of each element.  Anatomically, Weihenvenator is basically Torvosaurus, so is not that intriguing.  Rauhut et al. are the first I know to alter Carrano et al.'s basal tetanurine analysis however- "Several character definitions of the original list of Carrano et al. (2012), especially of cranial characters, were revised and taxa recoded correspondingly." "A complete documentation of the changes in character definition and character codings will be presented elsewhere (Rauhut and Pol, in prep.)."  So that's interesting.  They also "added the basal tyrannosaur Guanlong to the matrix in order to improve taxon and character sampling in coelurosaurs", which is good but not nearly enough to fix that issue.  They also deleted "the Chinese theropod Leshansaurus, as neither Carrano et al. (2012) nor we studied this taxon personally, and the published description (Li et al., 2009) is in Chinese, so codings could only be based on the sparse illustrations."  The illustrations are actually rather good, and the Chinese can be translated via Google Translate, so I'd argue against this.  In any case, their resulting tree matches Carrano et al.'s except Cryolophosaurus and Sinosaurus are outside Neotheropoda (their Averostra), Chuandongocoelurus is in a trichotomy with ceratosaurs and tetanurines, and Monolophosaurus is closer to megalosaurians than piatnitzkysaurids, all in Megalosauroidea.  Several taxa later added to the Carrano et al. matrix are not analyzed (e.g. Chilesaurus, Sciurumimus), which I think would be important when considering basal tetanurine phylogeny.  Rauhut was an author of Sciurumimus after all.  Finally, their informal supertree in figure 26 list "Anchiornithosaurs" in quote marks as a group sister to Avialae, which is... interesting.

Phylogeny found by Rauhut et al. (2016) after a posteriori exclusion of Streptospondylus using a modified version of Carrano et al.'s basal tetanurine matrix (modified after Rauhut et al., 2016).
But what about its size?  That was the big thing about the Minden Monster back in the day, with some paleontologists estimating its length as high as ~15 m (http://www.miketaylor.org.uk/dino/faq/s-size/predator/index.html#9).  Back in 2001 I estimated its size as ~7-8 m (http://dml.cmnh.org/2003Jul/msg00355.html) based on maxillary and fibular dimensions.  Rauhut et al. don't do a convincing job of calculating this.  They say "the maxilla is c. 82% of the size of that of Torvosaurus gurneyi, which was estimated to be approximately the size of Gorgosaurus or Daspletosaurus (c. 10 m in length and 4 to 5 tons in weight) by Hendrickx and Mateus (2014a)."  So that'd be ~8 meters long.  They then say "On the other hand, the caudal vertebrae are closely comparable in size to elements from a similar position in Torvosaurus tanneri, and the fibulae are even slightly longer than those referred to the latter taxon (Britt, 1991); this taxon was estimated to be approximately 9 m in body length by Britt (1991). Thus, Wiehenvenator is one of the largest theropods found so far in Europe and might only have been slightly smaller than Torvosaurus gurneyi."  Except that there are multiple Torvosaurus individuals present in the collection described by Britt, who never says what his ~9 meter estimate is based on.  If you use the scale bar on their skeletal reconstruction, Wiehenvenator is ~8.3 m long.  So good job me thirteen years ago.

References- Rauhut, Hübner and Lanser, 2015. A new theropod dinosaur from the late Middle Jurassic of Germany and theropod faunal turnover during the Jurassic. Libro de resúmenes del V Congreso Latinoamericano de Paleontología de Vertebrados. 62.

Rauhut, Hübner and Lanser, 2016. A new megalosaurid theropod dinosaur from the late Middle Jurassic (Callovian) of north-western Germany: Implications for theropod evolution and faunal turnover in the Jurassic. Palaeontologia Electronica. 19.2.26A, 1-65.

6 comments:

  1. I am very intrigued by "anchiornithosaurs" as well... I wonder if this is their equivalent to Chatterjee's Tetrapterygidae (without microraptorans of course, but the name of the family is still wrong if their type specimen for the family is Anchiornis)?

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  2. I'm pretty sure it's just a convenient label for the (Xiaotingia, (Pedopenna, Anchiornis, Eosinopteryx)) clade that was recovered in that exact position by Foth et al. (2014; see the paper for full ref), one of the analyses that the supertree is based on. As such, it's not "wrong", since it is clearly not intended as a formal name, and even its potential formal counterpart would only violate ICZN rules if it were erected as a family-level name.

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    1. Of course. It's just a weird choice for a name. Why not just use "anchiornithines"?

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  3. Evers et al. 2015 (Sigilmassasaurus) revised the presacral vertebral characters in the Carrano et al. matrix, and several papers have added characters to it, so this isn't the first to modify it. Hopefully the newly modified matrix is up on Morphobank soon, though. Wait, when was Sciurumimus added to this matrix?

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    1. The Rauhut et al. paper only focused on megalosaurids, not spinosaurids, even though Rauhut reached the exact same conclusion as Nizar Ibrahim (that Sigilmassasaurus is spinosaurid).

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