Phylogeny of Titanosauria #1

I am currently working on coding any and all titanosaurs into the matrix of Gonzalez et al (2016), describing Notocolossus. Just as a preliminary test, I have added a few new taxa, including Argyrosaurus, Hypselosaurus, Quetecsaurus and Puertasaurus. The results is shown below, although narrowed down to only show Titanosaurs.

Screen Shot 2016-06-18 at 8.29.49 PM

T – Titanosauria A – Argyrosauridae L – Lognkosauria P – Puertasaurinae M – Lithostrotia S – Saltasauridae O – Opisthocoelicaudiinae

The main things of interest if that Argyrosauridae is resolved, and places sister to Lognkosauria, and Hypselosaurus placed as a Saltasaurid, in a polytomy with Saltasaurus, Alamosaurus, Trigonosaurus, Nemegtosaurus, Opisthocoelicaudiinae, and what would normally be Nemegtosauridae, but currently excludes the name genus.


González Riga, Bernardo J.; Lamanna, Matthew C.; Ortiz David, Leonardo D.; Calvo, Jorge O.; Coria, Juan P. (2016). “A gigantic new dinosaur from Argentina and the evolution of the sauropod hind foot”. Scientific Reports 6: 19165. doi:10.1038/srep19165ISSN 2045-2322.

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Is Troodon really Troodon?

Troodon formosus is one of the first dinosaurs from North America ever named. Leidy (1856) described it for a single tooth with denticles on both the anterior and posterior carina. As of now, Troodon material includes the holotype tooth, the foot and caudal vertebra of the Stenonychosaurus holotype, the dentary of Polyodontosaurus, and multiple specimens referred to Stenonychosaurus, Troodon and Pectinodon. What is really interesting is how none of the holotypes of the above genera have overlapping material, and yet, a paleontological majority considers then synonyms. Not only that, but those genera also span some 10 million years and a large chunk of North America.

The one specimen that seems key to this assignment is CMN (or NMC) 12340, which includes the postorbital skull, multiple vertebral bones, and most of the hindlimb. As far as I know, this specimen is the basis on which nearly all specimens can be assigned to Troodon, being the only one including cranial and post cranial material. But there is a problem, CMN 12340 should be kept separate from Stenonychosaurus.

This is NMC 8539, the holotype of Stenonychosaurus from Sternberg (1932)

Now, as you can see below, in CMN 12340, the third metatarsal is longer than the fourth, but in the above picture, looking closely, it is reversed in NMC 8539.

CMN 12340, the linking specimen between Troodon and Stenonychosaurus. From Russell (1969)
The reconstruction of the metatarsus in Russell (1969), based on NMC 8539, seems to be in error, possibly why other studies have followed with minimal questions. Now remains the question of where everything else falls.
The Troodon holotype is a single tooth, likely from the dentary, so other overlapping material must be found in a dentary. Russell (1948), provides this dentary, ROM 1445, with a tooth that, and I concur, is quite similar to that of the holotype. From here, Sues (1977), describe a “Saurornithid” dentary from Judith River, PMA A P67.14.39, which I find to share many features of ROM 1445, and could be referrable to Troodon.
NMC 8540 is the holotype of Polyodontosaurus Gilmore (1932), and apparently it is very similar to Rom 1445, with both assigned to Troodon by Russell (1969). But, and I hope you can tell, they are actually quite different.
From right to left: Polyodontosaurus, ROM 1445, PMA A P67.14.39 from Currie (1969), Russell (1948) and Sues (1977) respectively
  •  Leidy, J. (1856). “Notice of remains of extinct reptiles and fishes, discovered by Dr. F. V. Hayden in the Bad Lands of the Judith River, Nebraska Territories”. Proceedings of the Academy of Natural Science Philadelphia 8: 72–73.
  • Sternberg, C.M. (1932). Two new theropod dinosaurs from the Belly River Formation of Alberta. Canadian Field-Naturalist 46(5):99-105.
  • Russell, D.A. (1969). A new specimen of Stenonychosaurus from the Oldman Formation (Cretaceous) of Alberta. Canadian Journal of Earth Sciences, 1969, 6(4): 595-612, 10.1139/e69-059
  • Russell, L.R. (1948). The Dentary of Troödon, a Genus of Theropod Dinosaurs. Journal of Paleontology. 22(5): pp. 625-629.
  • Sues, H.D. (1977). Dentaries of small theropods from the Judith River Formation (Campanian) of Alberta, Canada. Canadian Journal of Earth Sciences, 1977, 14(4): 587-592, 10.1139/e77-061.
  • C. W. Gilmore. 1932. A new fossil lizard from the Belly River Formation of Alberta. Transactions of the Royal Society of Canada, section 4, series 3. 16:117-119.
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What I’ve been doing

So, I haven’t done much in a while, but I have been busy. I in fact have been getting ready for what may be the largest morphological phylogenetic analysis EVER, one including nearly Every Single Dinosaurian taxon, that is either valid or a nomen dubium. Of course, I cannot have this any more specific than genera, so I shall be recording the specimens I base my codings on in an appendix. Honestly, I don’t think Ill be able to use all characters accounted for in more focus analyses, as I believe that would bring the total count well over the 5 000.


Many characters I choose are based upon previous phylogenies, but I am also introducing some new ones. These hopefully will balance out that I have 1 019 taxa that I will be coding, from Lagerpeton to Ichthyornis. Suggestions on papers where I can find characters or high-resolution images of specimens of relatively enigmatic genera would be appreciated.


  • SerenoPC. The evolution of dinosaurs. Science 284:2137-2147. (26)
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My take on english taxa #1

So I’m beginning a new series on english taxa, starting with the oldest of any, Rutellum impicatum. Now this name currently is invalid, but it has a very important story to tell. A single tooth was collected near Whitney, Oxfordshire, and later described as a “fish tooth” by Lhuyd. Now in 1699, when this was published, all fossils were simply believed to be fakes, pretty much rocks made by the earth that resembled animal bones. Lhuyd had a habit of describing all his “rocks” and giving them latin names, and for this tooth he chose Rutellum impicatum, meaning “pitch covered shovel”. Lhuyd also figured this tooth and provided a description, stating that the tooth was bright black and was found near “Caswelliana” near Whitney, Oxfordshire. However, according to Delair and Serjeant (2002), there is no civilization named Caswell anywhere near Whitney, and the closest Caswell is apparently in Wales. But Delair believed that Caswell was a simple misspelling for Carswell. Any british people can easily give me pointers on what I get wrong, as these are your cities and bones.

Rutellum is often noted to be a cetiosaurid based on the mid-jurassic age and location, however, I have noted that Rutellum bears and lacks many features similar with other sauropods, and based on simple morphology it appears to be intermediate between Shunosaurus and Cetiosaurus? teeth. But one intriguing thing is that the tooth bears a single feature that is only shared with Camarasaurus among sauropods, an anteroventral projection of the crown ventral to the dorsal edge of the root. This is about it for Rutellum, but I give you the only known illustration of the tooth, which is now lost.

Rutellum tooth

  1. Delair, J.B., and Sarjeant, W.A.S. (2002). The earliest discoveries of dinosaurs: the records re-examined. Proceedings of the Geologists’ Association 113:185–197.
  2. Lhuyd, E. (1699). Lithophylacii Britannici Ichnographia, sive lapidium aliorumque fossilium Britannicorum singulari figura insignium. Gleditsch and Weidmann:London.
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Haestasaurus becklesii is a moderately sized macronarian from the Wealden of England. It was known as “Pelorosaurus” becklesii for a long time since its original description, with its humerus, the only overlapping material, significantly more robust than that of Pelorosaurus brevis. In the middle of summer this year, Paul Unchurch, Phil Mannion, and Mike Taylor published the first detailed redescription. Among the known material is the humerus, associated with a radius, and an ulna. But quite uniquely among all sauropods is the association of a skin impression with the elbow region of these remains. The scales are large and non-overlapping, but based on photographs I’ve seen they become smaller towards the edge of what is preserved.

Haestasaurus skeletonThe systematics of Haestasaurus have been under question for some time, and it was considered to be a primitive titanosaurian for some time. However, two of the three analyses found it to be a primitive macronarian, either a camarasaurid, or a non-camarasauromorph macronarian.

The skin impression of Haestasaurus, lies on a joint, a region where predators may attack to main an animal. That makes it seem like the more attacked regions would have had similar scales – the hindlimb, the underside, and the neck. Thus, In my life restoration based on the above skeletal which is also mine, I have added these pebbly and larger scales to these regions.

Haestasaurus reconstruction

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Why Not to delete taxa A Posteriori or A Priori

So I’ve been making excursions into phylogenetic analysing, and based on advice from Mike Taylor I’ve added a dental character, Euhelopus and Brachiosaurus nougaredi. Based on what I’ve found, I can safely say that NO MATTER WHAT, all characters and taxa add to an analysis, and if there is a dissolved clade that you want resolved, add more taxa or characters.

The strict consensus, which is the only really important analysis, is resolved as (Outgroup (Cetiosaurus, H. priscus, H. delfsi, H. sp., H. utterbacki, Tataouinea, Camarasaurus, Brachiosaurus, B. nougaredi, Futalognkosaurus, Apatosaurus minimus, Atlantosaurus, Euhelopus (A. ajax + Elosaurus) ) ). Now, Atlantosaurus is a pretty bad taxa, second worst known after B. nougaredi in this analysis, so I removed it in one analysis. This generated the tree (Outgroup, all other taxa), which actually dissolves the clade of A. ajax + Elosaurus. Now for the final analysis I removed B. nougaredi, and the tree was resolved as the exact same as with all taxa except without B. nougaredi.

This shows that neither tree was improved by removing a single fragmentary taxon, but to prove my point further I decided to remove both and generate a tree. With both removed, the tree resolved the same as with only Atlantosaurus removed. Now for some reason Atlantosaurus is the taxon that supports the clade of A. ajax + Elosaurus, but I’m not sure how.

I think this is good proof that analyses are better with more information, and further analyses should put this into account before deleting A Priori or A Posteriori.

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A Phylogeny of Pure Sacral Characters

I have for a while been intrigued by sauropods, and how Atlantosaurus related to Apatosaurus. Of course because the former would be the senior synonym. But I didn’t want to code it into a large analysis. So I decided to place it in a purely sacral-based analysis. So I (somehow, honestly I’m not sure how, but I think it was a trial version) got PAUP* for free and added in my matrix. In the analysis, with the matrix based on my observations of photographs, with characters after multiple authors including Tschopp et al..

There were 25 characters, and 13 taxa, so not exactly the most comprehensive analysis. The outgrip was hypothetical, and all zeros. Taxa included were CetiosaurusFutalognkosaurusBrachiosaurusCamarasaurusElosaurusApatosaurus ajax, A. minimumAtlantosaurus, and the three proposed species of Haplocanthosaurus in addition to H sp. I expected to see the normal group with Cetiosaurus as most basal, diplodocoidea formed, and macronaria together. However, something strange happened.

Like proposed by Mike Taylor and Matt Wedel, Apatosaurus minimus grouped with Camarasaurus and Brachiosaurus. Both the strict consensus and 50% majority trees were similar, with the strict consensus simply more dissolved. Cetiosaurus was most basal other than the outgroup. But up next was a polytomy of Futalognkosaurus and Atlantosaurus. This is strange, as normally these two fall into the ends of separate neosauropoda. Up next was what would normally be Neosauropoda. This split into two groups, Presumably diplodocoidea and macronaria. However, the split seemed to be more Rebbachisauridae/Diplomacronaria. In Rebbachisauridae was a clade of (Haplo delfsi, Haplo priscus (Haplo sp. (Haplo utterbacki + Tataouinea) ) ). And then there is Diplomacronaria, which is just a name I made up. It includes (Apato ajax ( Elosaurus ( Apato minimus (Camarasaurus + Brachiosaurus) ) ) ). This is really quite a weird result, but I think it could be expected with the small number of taxa and the purely sacral-based matrix. Both the strict consensus and 50% majority trees are shown below.

50% majority tree

50% majority tree

Strict consensus tree

Strict consensus tree

Things to note include that there were 15 possible trees for the strict consensus. In the analysis, when there was more than one species the first letter is directly following the generic name. I can provide people with the nexus file if they would like it.

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