Looks like “Pelorosaurusbecklesii is actually Haestasaurus becklesii!

June 3, 2015

Well, who knew? There I was posting images of “Pelorosaurusbecklesi‘s humerus, radius and ulna, and skin impression. There I was saying that this beast is due a proper description, and warrants its own generic name. And what should come out today but a new paper by Paul Upchurch, Phil Mannion and, oh yes, me, which does exactly that.

Screen Shot 2015-06-03 at 19.05.12

The headline news is the long-overdue establishment of a new genus name for this species — something that we’ve known was needed at least since Upchurch’s (1993) dissertation. Paul and Phil came up with the name Haestasaurus, from “Haesta”, the name of the putative pre-Roman chieftain whose people apparently settled the area of Hastings and gave the town its name. It’s nice that I can finally stop typing the scare-quotes around the no-longer-relevant old genus name “Pelorosaurus“!

Upchurch et al. 2015: figure 2. Left humerus of Haestasaurus becklesii (NHMUK R1870). A, anterior view; B, posterior view; Abbreviations: af, anconeal fossa; dp, deltopectoral crest; hh, humeral head; ltf, lateral triceps fossa; mtf, medial triceps fossa.

Upchurch et al. (2015: figure 2). Left humerus of Haestasaurus becklesii (NHMUK R1870). A, anterior view; B, posterior view; Abbreviations: af, anconeal fossa; dp, deltopectoral crest; hh, humeral head; ltf, lateral triceps fossa; mtf, medial triceps fossa.

(As you can see, the photography is rather better than in my own illustrations, which I made independently some years ago.)

Of course Paul has had an eye on this work, on and off, since the early 1990s. Then in the late 2000s, when I was working on Xenoposeidon and other Wealden sauropods, I started work independently on a redescription — which of course is why I prepared the figures that have appeared in the last few posts. But that work petered out as I started working more on other specimens and on the problems of the sauropod neck. More recently, Paul and Phil hunkered down and got the nitty-gritty descriptive work done.

Once they had a complete draft manuscript, they very graciously invited me onto the authorship — not something they had to do, but they chose to based on my previous interest in the specimen. My contribution was minor: I provided two of the illustrations, tidied up the early versions of several others, and did an editing pass on the text.

Upchurch et al. (2015: figure 1). Map showing England and Wales, with boundaries for English counties. The magnified inset shows the Isle of Wight and East and West Sussex in more detail, marking the positions of selected major towns/cities and the fossil localities mentioned in the main text. Based on

Upchurch et al. (2015: figure 1). Map showing England and Wales, with boundaries for English counties. The magnified inset shows the Isle of Wight and East and West Sussex in more detail, marking the positions of selected major towns/cities and the fossil localities mentioned in the main text. Based on “English ceremonial counties 1998” by Dr. Greg, http://en.wikipedia.org/wiki/File:English_ceremonial_counties_1998.svg. CC By-SA 3.0.

(This map is one of the two illustrations that I provided; the other is the multi-view photograph of the Pelorosaurus conbeari humerus.)

I’m grateful to Paul and Phil, both for inviting me onto this project, and for taking into account my strong preference for an open-access venue. It’s largely because of the latter that the paper now appears in PLOS ONE, where the glorious colour illustrations appear at full resolution and may be re-used for any purpose subject to attribution.

So: what actually is Haestasaurus? Is it the early titanosaur that we’ve all been assuming? The unexciting answer is: we don’t really know. Our paper contains three phylogenetic hypotheses (all of them Paul and Phil’s work, I can’t take any credit). These results are from adding Haestasaurus to the Carballido and Sander (2014) matrix, to the Mannion et al. (2013) standard discrete matrix and to the Mannion et al. (2013) continuous-and-discrete matrix. Only the last of these recovers Haestasaurus as a titanosaur — as sister to Diamantinasaurus and then Malawisaurus, making it a lithostrotian well down inside Titanosauria.

Both both of the other analyses find Haestasaurus as a very basal macronarian — outside of Titanosauriformes. Here is the result of the analysis based on Carballido and Sander’s Europasaurus matrix:

Upchurch et al. (2105: figure 15). Strict consensus tree (CSM). A strict consensus tree based on the 28 most parsimonious trees generated by analysis of the Carballido and Sander [19] data matrix with the addition of Haestasaurus and six new characters (Tendaguria excluded a priori). GC values (multiplied by 100) are shown in square brackets for all nodes where these values are greater than 0. The monophyletic Diplodocoidea has been collapsed to a single branch in order to reduce figure size. Abbreviation: Brc, Brachiosauridae.

Upchurch et al. (2105: figure 15). Strict consensus tree (CSM). A strict consensus tree based on the 28 most parsimonious trees generated by analysis of the Carballido and Sander [19] data matrix with the addition of Haestasaurus and six new characters (Tendaguria excluded a priori). GC values (multiplied by 100) are shown in square brackets for all nodes where these values are greater than 0. The monophyletic Diplodocoidea has been collapsed to a single branch in order to reduce figure size. Abbreviation: Brc, Brachiosauridae.

As you can see, Haestasaurus is here a camarasaurid, making it (along with Camarasaurus itself) the most basal of all macronarians. In the second analysis — the one using discrete characters only from Mannion et al.’s Lusotitan paper — Haestasaurus is again in the most basal macronarian clade, but this time as sister to Janenschia and then Tehuelchesaurus. (In this topology, Camarasaurus is the next most basal macronarian after that three-taxon clade.)

So it looks like Haestasaurus is either a very basal macronarian or a pretty derived titanosaur. We don’t know which.

But, hey, at least it has a proper name now!

Acknowledgements

It’s Matt’s birthday today. I’d like to dedicate a sauropod to him, but I don’t have the authority to do that. So instead, I dedicate this blog-post to him, and declare it the Mathew J. Wedel Memorial Blog Post.

References

Advertisements

10 Responses to “Looks like “Pelorosaurusbecklesii is actually Haestasaurus becklesii!”

  1. Matt Wedel Says:

    Aww, thanks, dude! I can state definitively that it’s the nicest blog-post anyone’s ever dedicated to me.

    So far, that is. The gauntlet has been thrown down, folks!


  2. Never thought I’d see the day that Brachiosaurus was recovered as a titanosaur.

    I find it somewhat interesting that Haestasaurus and Janenschia seem to be sister taxa. Multiple early putative titanosaurs of controversial affinity? Boom, they’re actually relatives of one another!

  3. Andrew Stuck Says:

    Haha, well done with the last string of blog posts: you managed to get me pretty invested in a sauropod I’d never heard of just in time to spring a new paper on me.
    “Yeah, he’s right! ‘Pelorosaurus’ SHOULD get a proper name, dangit! Wait, what? Oh. …clever girl.”

  4. Mike Taylor Says:

    My pleasure, Matt.

    assuming-dinosaur, Brachiosaurus can’t be a titanosaur by definition, since the standard definition of Titanosauria is as the clade of all organisms more closely related to Saltasaurus than to it. See the discussion on page 804 of my 2009 brachiosaur paper. I agree it’s unusual for the brachiosaurs to come out further down the macronarian tree than Euhelopus, but I don’t think it’s that weird an idea.

    Andrew, I’m glad you walked into it :-)


  5. I am aware of that definition, but (Andesaurus+Saltasaurus) seems to be the most widespread definition these days. I suppose most people would agree that that definition is undesirable if it were to include Brachiosauridae, though.

  6. Mike Taylor Says:

    What makes you say that (Andesaurus + Saltasaurus) is the most widespread definition of Titanosauria?

  7. Mark Evans Says:

    Lucky old Haesta, with two fossil tetrapods named after him. Now there’s Haestasaurus as well as the leptocleidid plesiosaurian Hastanectes.


  8. It was used in, for example, D’Emic’s (2012) paper on titanosauriform phylogeny, the description of Dreadnoughtus, Mannion et al.’s (2013) paper on Lusotitan, and Salgado et al.’s (1997) paper on titanosaur phylogeny–which makes it the oldest definition for the clade I’m aware of. I’ve only been able to find one or two papers off the top of my head to reference each of the other three definitions I’m aware of (with Euhelopus and/or Brachiosaurus as external specifiers).


  9. […] my blog-post announcing Haestasaurus as the new generic name for the misassigned species […]


Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

%d bloggers like this: