Subadult and adult Tropeognathus compared

Holgado and Pegas 2020 name several toothy crested rostral pieces
they assign to Anhangueridae, Coloborhynchinae and Tropeognathinae, subsets of the clade Ornithocheiridae (Seeley 1870).

More interesting due to its completeness,
was the Holgado and Pegas page-wide photo of the BSp 1987 I 47 specimen of Tropeognathus (Fig. 1, Wellnhofer 1987). Here the ’47’ specimen is compared to the larger holotype, BSp 1987 I 46, and to the smaller Scaphognathus holotype (Fig. 1, GPIB 1304, No. 109 of Wellnhofer 1975), a distant ancestor of Tropeognathus in the Large Pterosaur Tree (LPT, 251 taxa).

Quick note to readers after October 19, 2020:
Co-author Pegas sent a comment noting the 47 specimen was a typo and should be 46 instead. I asked about the scale bar differences and am awaiting that reply at present.

Figure 1. A subadult and adult specimen of Tropeognathus compared to a distant relative, Scaphognathus.

Figure 1. A subadult and adult specimen of Tropeognathus compared to a distant relative, Scaphognathus.

Holgado and Pegas provided a cladogram of a clade of pterosaurs
formerly considered Ornithocheiridae, Lanceodontia. Strangely, their outgroup is the derived istiodactylid, Lonchodraco giganteus, which we looked at earlier here and nested with the unnamed SMNS PAL 1136 specimen, which was omitted from their cladogram.

By contrast
In the LPT ornithocheirids arise from small taxa like Yixianopterus, Mimodactylus and before them the Cycnorhamphus clade and before them the tiny Late Jurassic pterosaurs, BM NHM 42735, Gmu10157, TM 13104 and three Scaphognathus specimens (109, SMNS 59395 and 110 and  of descending size. None of these are included in Holgado and Pegas.

There are quite a few nomenclature problems
in the Ornithocheridae that make the taxonomy unnecessarily confusing.

According to Wikipedia,
“Back in 1987, Wellnhofer had named a second species called Tropeognathus robustus, based on specimen BSP 1987 I 47, which is a more robust lower jaw. In 2013 however, T. robustus was considered as a species of Anhanguera, resulting in an Anhanguera robustus.” Comparing the 46 and 47 specimens (Fig. 1) show they are conspecific, or at least congeneric. This clade becomes increasingly confused with every new author or set of authors. Strange that such closely related taxa are generically split while the several dozen variations in Rhamphorhynchus and Pteranodon are ignored.

The first species of Tropeognathus mesembrinus has several synonyms.

  • Anhanguera mesembrinus (Wellnhofer, 1987)
  • Coloborhynchus mesembrinus (Wellnhofer, 1987)
  • Criorhynchus mesembrinus (Wellnhofer, 1987)
  • Ornithocheirus mesembrinus (Wellnhofer, 1987)

Ornithocheiridae Seeley 1870, named when only a few bits and pieces were known

Ornithocheiromorpha Andres et al., 2014, incorrectly nested within Pteranodontoidea.

Pterodactyloidea Plieninger, 1901, adding taxa splits up this traditional clade.

The disappearance of the naris in scaphognathid pterosaurs.

Figure 2. The disappearance of the naris in scaphognathid pterosaurs. Click to enlarge figure 1 to see the tiny naris in the subadult specimen of Tropeognathus, more sealed over in the adult.

The subadult specimen (specimen ’47’)
of Tropeognathus (Fig. 1) documents a vestige, slit-like naris that disappears in the larger ’46’ specimen. If you can’t see it here, click to enlarge.

Rostral crest
Comparing the subadult to the adult specimen (Fig. 1) demonstrates no growth in the size of the rostral crest. Rather the back half of the skull is slightly larger.


References
Holgado B and Pegas RV 2020. A taxonomic and phylogenetic review of the anhanguerid pterosaur group Coloborhynchinae and the new clade Tropeognathinae. Acta Palaeontologica Polonica 65 (X): xxx–xxx.
Wellnhofer P 1975a. Teil I. Die Rhamphorhynchoidea (Pterosauria) der Oberjura-Plattenkalke Süddeutschlands. Allgemeine Skelettmorphologie. Paleontographica A 148: 1-33. 1975b. Teil II. Systematische Beschreibung. Paleontographica A 148: 132-186. 1975c.Teil III. Paläokolgie und Stammesgeschichte. Palaeontographica 149: 1-30.
Wellnhofer P 1987. New crested pterosaurs from the Lower Cretaceous of Brazil. Mitteilungen der Bayerische Staatssammlung für Paläontologie und historische Geologie 27: 175–186; Muenchen

/wiki/Tropeognathus
wiki/Scaphognathus
wiki/Criorhynchus

 

6 thoughts on “Subadult and adult Tropeognathus compared

  1. Hi. You are “tracing” some “ontogenetic changes” by comparing “two” specimens that, actually, are the same one. Specimen “47” is so obviously a typo in the Holgado & Pêgas (2020) paper – it should be indeed 46, and any pterosaur worker I know would notice this. I know you won’t stop doing what you do, but I am writting this comment anyway because I am thinking about any unsuspecting readers.

    • Thank you for your input, Rodrigo. I wondered about this as well, but noticed the proportional and scale bar differences. So, is this an example of a ‘perfect storm’ of three mistakes occurring at once in your paper? I’ve already admitted to correcting over 100,000 mistakes over the last ten years. Why would you think “I know you won’t stop doing what you do”?

      • Thanks for not deleting my comment. Typos and wrong scales are human mistakes, which I am sorry for.

        Small differences in proportions in photos are common according to angle, proximity, and lens, especially in large specimens; this is why comparing proportions from photos is precipitated, and why measurements are always taken first-hand. So this is my warning to the readers: be carefull before blogging precipitated conclusions based solely on photos.

      • Which scale bar is correct? Alternatively, what is the skull length in cm?

        I only delete comments that are obvious SPAM (unrelated to content), comments that are derogatory or ad hominem, or comments that contain a short list of ‘four-letter words’ usually said in anger. I encourage scientific comments and corrections otherwise. Several years ago there was a backup of comments due to my misunderstanding of a web button.

  2. Ok, thanks, and thanks for asking;maximum skull length was recorded as 63 cm by Wellnhofer (1987) and then 64 by Veldmeijer (2003), I measured 63.7 for pmax-parietal crest and 61 for pmax-sq.

  3. Also, please notice that the photo from Holgado & Pêgas (2020) is in right view. The other photo you showed is in left view, and the specimen is asymmetrical due to distortion (Wellnhofer 1987).

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