Another look at Yutyrannus

Figure 1. Comparing the skulls of Eutyrannus (center) to Allosaurus (above) and Tyrannosaurus (below). Which one appears to share more traits with Yutyrannus? See text for details. The pink portion of the nasal appears to be a lateral crest, as in Allosaurus. Note the central frontal horn. It is hollow, like that of Majungasaurus.

Figure 1. Comparing the skulls of Eutyrannus (center) to Allosaurus (above) and Tyrannosaurus (below). Which one appears to share more traits with Yutyrannus? See text for details. The pink portion of the nasal appears to be a lateral crest, as in Allosaurus. Note the central frontal horn. It is hollow, like that of Majungasaurus.

So, the theropod community
is not happy with the large reptile tree nesting of Yutyrannus with Allosaurus (Figs. 1, 2) and the nesting of Microraptor with Compsognathus (see tomorrow).

I don’t blame them.
A larger matrix with more taxa and more characters specific to theropods (Cau et al. 2015) nests these provisional sisters elsewhere — Microraptor with Velociraptor and Yutyrannus with Tyrannosaurus. Shifting Microraptor next to Velociraptor in the large reptile tree adds 30 steps. Shifting Yutyrannus to T-rex adds 25.

The large theropods
under consideration (Fig. 1) all have a robust skull and share a common ancestor, a sister to Coelophysis in the Late Triassic. Each of the three candidates has prominent lacrimal horns (more prominent in A and Y), an elevated naris (larger in A and Y) and a deep angled jugal (PO process more gracile in A and Y). The nasals also produce lateral crests in A and Y, but crushed into the parasagittal plane in Y.

Note
I have replaced the old skull of Yutyrannus based on the original published drawing with a DGS tracing (Fig. 1) that appears to be more accurate as it replaces certain broken pieces to their invivo positions. The changes did not affect the earlier tree topology.

Yutyrannus/Allosaurus traits
Here following traits scored Yutyrannus with Allosaurus opposed to T-rex.

  1. A and Y share a horizontal premaxilla ventral rim. In T it rises anteriorly.
  2. A and Y share a vertical quadratojugal that interlocks with the squamosal. The quadratojugal of T is hourglass-shaped.
  3. A and Y share a shallow angled posterior dentary. The posterior dentary of T is almost vertical.
  4. A and Y share a ventral naris composed of equal parts premaxilla and nasal. In T the premaxilla extends the majority of the rim.
  5. In A and Y the skull is less than half the length of the presacral column. In T the skull is not less than this length.
  6. In A and Y the nasal is widest at mid length. Not so in T.
  7. In A and Y the lacrimal was deeper than the maxilla. Not so in T.
  8. In A and Y the frontals lack posterior processes. Not so in T.
  9. In A and Y the coronoid process is absent. It is low in T.
  10. In A and Y cervical centra are longer than tall. Not so in T.
  11. In A and Y the cervicals do not decrease cranially. Not so in T.
  12. In A and Y the sacrals are not fused to the ilia. Fused in T.
  13. In A and Yh the second caudal transverse processes are not > centrum width. > in T.
  14. In A and Y a mineralized sternum is absent. Present in T.
  15. In A and Y mc2-3 align with m1.1 They do not align with that joint in T.
  16. In A and Y the ilium anterior process is not > the acetabulum length. It is > in T.
Figure 2. Yutyrannus (middle) compared to Allosaurus (above) and Tyrannosaurus (below). Not to scale. Which one appears to share more traits with Yutyrannus?

Figure 2. Yutyrannus (middle) compared to Allosaurus (above) and Tyrannosaurus (below). Not to scale. Which one appears to share more traits with Yutyrannus?

Also note
the large three-fingered hand in Y (relatively larger than in A, the lack of a pinched metatarsal 2 in Y and a long narrow H-shaped palatine in A and Y, not in T.

Of course 
there is also a list of traits that link Allosaurus with T-rex to the exclusion of Yutyrannus. That’s par for any phylogenetic analysis.

References
Madsen JH Jr. 1993 [1976]. Allosaurus fragilis: A Revised Osteology. Utah Geological Survey Bulletin 109 (2nd ed.). Salt Lake City: Utah Geological Survey.
Marsh OC 1877. Notice of new dinosaurian reptiles from the Jurassic formation. American Journal of Science and Arts 14: 514–516.
Osborn HF 1905. Tyrannosaurus and other Cretaceous carnivorous dinosaurs. Bulletin of the AMNH (New York City: American Museum of Natural History) 21 (14): 259–265′
Xu X, Wang K, Zhang K, Ma Q, Xing L, Sullivan C, Hu D, Cheng S, Wang S et al. 2012. A gigantic feathered dinosaur from the Lower Cretaceous of China. Nature 484 (7392): 92–95. doi:10.1038/nature10906.  PDF here.

wiki/Yutyrannus
wiki/Allosaurus
wiki/Tyrannosaurus

Advertisements

8 thoughts on “Another look at Yutyrannus

  1. As you know, John, everything is provisional. With the data I have and the resulting scores I must (at present) stand by my results — pending additional data. The creation of reconstructions helps. Sister taxa taxa should look similar. They do in the large reptile tree. The Cau et al. 2015 study did not create reconstructions. They also nested Balaur on the bird side of Archaeopteryx, a result not recovered by the large reptile tree. And their topology at those nodes appears unlikely to untenable. Take a look at those taxa at reptileevolution.com and you may come to a similar conclusion. And by the way, it’s okay to come to different conclusions. Ultimately the conclusions will converge.

  2. 1, 2 (Yutyrannus’ also interlocks with the squamosal), 3, 5, 6, 7, 9, 10, 15 (because Tyrannosaurus has a reduced mcIII), the large tridactyl hand and the unpinched mtIII are all plesiomorphic in Yutyrannus and Allosaurus (note how many are shared with Gorgosaurus). 11 isn’t true in Tyrannosaurus (fig. 50 in Brochu, 2003). 12 is untrue in at least some Tyrannosaurus (Sue- Brochu, 2003; holotype- Osborn, 1916). For 13, I’m assuming you’re not taking into account that both have backturned transverse processes, so that Allosaurus’ look short in Madsen’s (1976) anterior/posterior views. For 14, no Tyrannosaurus doesn’t have an ossified sternum- the structure in it and Gorgosaurus is a mass of fused gastralia (Brochu, 2003 again).

    So again, you don’t know what you’re talking about. For today’s obvious mistake, Yutyrannus (like most non-bird theropods) has four phalanges on manual digit III, clearly shown in figure S2c of its description. Not three like you show. I also like how your pre- and postacetabular processes are cut off where the cracks in the matrix are, your pubis and ischium don’t articulate under the acetabulum, the femur is in posterior view and the humerus in anterior view, and I don’t even know what you did with the palate and area above the laterotemporal fenestra. The authors showed you how those look in their illustration (though leaving out the articulated vomer and pterygoids), but you have some unconnected supratemporal area and an odd flat palate…

    You’re really just exposing how little you know and how terrible DGS is at this point.

  3. Imagery available is poor, resolution is low. So I am at a disadvantage from the start. All your comments are likely valid. Even so, none of these changes change the nesting. Look through the antorbital fenestra. The palate is not portrayed as flat. The sub acetabular pubis was repaired before reading this. DGS is a method. In order to get the most out of it you need a good night’s sleep, several ounces of expertise and avoid distractions. Every attempt I make at tracing a fossil is a “first date”. It almost never comes out perfectly, as I have discovered tens of thousands of times. I appreciate your valuable comments. They are useful in making the necessary changes. However your snippy attitude makes you sound like a hater, as you attempt to blackwash my entire output by pointing out mistakes that anyone might make in similar circumstances. Get it together, Mickey. Helpers are appreciated. Haters are avoided.

    • You have the same supplementary info figures I do (they’re free). It’s just that I have decades of theropod experience so that I can usually recognize what morphologies exist. And yes, I do blackwash your entire output. When I’m familiar with the taxa you post on, I know you make tons of mistakes. Thus when you post on taxa I’m unfamiliar with, you’re also probably making tons of mistakes. Call me a hater if you want, but since you utterly refuse to fix your methods (e.g. have you ordered appropriate characters yet?), you show no willingness to change. Any person honestly interested in the truth would say “Okay, I’ll order those characters, and separate those correlated characters, etc., then run the analysis again” Why don’t you just do that? You just know you’re right, about every group, and thus everybody else is wrong about basically everything. Is it REALLY more likely that every other researcher is wrong about every tetrapod group, but that you are correct? How would you possibly defend that?

  4. Here’s my defense. You’ve heard this before: I correct errors whenever I find them or they are pointed out to me. Tens of thousands over the last five years. The cladogram recovers a logical stream of gradually evolving characters — which is the ideal result. I examine my MacClade charts for typos and autapomorphies. All sister taxa actually look like they could be sister taxa, with no odd matches. I show my work — so others can find errors if present and I can make corrections. Every taxon in the cladogram affects and is affected by every other taxon. By maximizing taxon inclusion I have minimized tradition, bias and paradigm. Over the rest of the cladogram that has opened up new solutions to old problems. Perhaps as I add more theropods my tree topology will begin to match that of others. So far, it does not appear to be doing so.

    I don’t “know” I’m right. I report whatever pops up during the day. I change scores and results when better data or additional taxa make it necessary. Everything is provisional. I’m seeing everything for the first time. I show what I have recovered with sometimes great and sometimes crappy data.

    I don’t assume that a past tree is error free and includes all relevant taxa and excludes all irrelevant taxa then add my new taxon to it. Other workers rely on tradition for this. I don’t order characters. Some characters are repeated. Others are flawed. Still others are correlated (like more verts and shorter limbs).

    I’m not sure, but I think I’m recovering a different theropod tree because I am working from a reconstruction and many of my traits are x vs. y comparisons and ratios, whereas the pros are mostly using bumps, depressions, ridges and other minutia best studied on the roadkills.

    Hope this helps. More data and fewer accusations are preferred for all scientific discourse. Blackwashing my entire output?… that means if I ever do come up with something valid you will not recognize it. That explains soooo much.

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