New Triassic basal dimorphodontid: Caelestiventus

Britt, et al. 2018
bring us a new desert-dwelling Triassic pterosaur, Caelestiventus hanseni (Figs. 1, 2; BYU 20707, Museum of Paleontology at Brigham Young University) from western North America. They nest it with Dimorphodon (Fig. 1), from the English Jurassic, although Preondactylus (Fig. 3) is also similar, with a huge naris, and also from the Late Triassic. Caelestiventus is larger than most Triassic pterosaurs, with a wingspan of at least 1.5 meters. Coeval Raeticodactylus is similar in size and also fills in the lower orbit with a thin sheet of bone.

Britt, et al. also confirm the nesting
of ‘Dimorphodon’ weintraubi with anurognathids, something first published by Peters 2011 and reported here the same year.

Unfortunately
Britt and colleagues nest anurognathids as the sister taxa to Dorygnathus due to taxon exclusion. In the large pterosaur tree (LPT, 234 taxa) anurognathids nest with and arise from dimorphodontids. Among the many taxa missing from the Britt et al. tree is the IVPP giant embryo anurognathid, a completely preserved specimen, and Mesadactylus, another Jurassic transitional sister basal to anurognathids… also from North America.

Figure 1. Triasic Caelestiventus skull compared to Jurassic Dimorphodon. Readers, don't do the easy thing and go to the Wellnhofer diagrams for your pterosaur skulls. Use real data.

Figure 1. Triasic Caelestiventus skull compared to Jurassic Dimorphodon. Readers, don’t do the easy thing and go to the Wellnhofer diagrams for your pterosaur skulls. Use real data.

It’s always wonderful to see a new pterosaur taxon.
Congratulations to all coauthors on this paper.

Figure 4. The skull of Bergamodactylus (MPUM 6009)

Figure 2. The skull of Bergamodactylus (MPUM 6009) the most primitive pterosaur in the LPT.  No antorbital fossa here and not tested by Britt et al.

The sculptor of the skull
(Fig. 1) put a ‘Roman nose’ on the restoration of Caelestiventus. That illustration will float around the paleo-universe forever. However, I take my cue from the Triassc age of the specimen and the downturned dentary, as in the Triassic basalmost pterosaur, Bergamodactylus (Fig. 2), which has an unexpanded naris, to create a more transitional naris (Fig. 1), and from Preondactylus (Fig. 3), a closer relative with a large, yet straight naris, rather than create a derived version with more of a curve than Dimorphodon had.

Figure 3. Preondactylus from the Late Triassic is basal to Dimorphodon in the LPT.

The staff or hired artist
charged with illustrating Caelestiventus in vivo (Fig. 4) made a few mistakes. These were generated, no doubt, by the many false paradigms floating around out there. Here they are shown and corrected. (Just found out the artist is Michael Skrepnick, Dinosaursinart.com)​

  1. The manual claws should point down toward the palm, as in most tetrapods
  2. Pedal digit 5 should be on the lateral side of a much larger foot and it should not be involved in the uropatagia.
  3. The tail should be shorter if closer to Dimorphodon than to Preondactylus. Otherwise it might be that long.
  4. The rostrum is straight inLate Triassic sister, Preondactylus, so  perhaps a straight angled rostrum is more appropriate here.
  5. The wing membranes were stretched between elbow and wing tip, as all soft tissue pterosaur fossils demonstrate.
  6. The cranium probably tipped down posteriorly, as all related taxa demonstrate (Figs. 1–3).
Figure 2. Pity the poor staff artist trying to get a pterosaur correct in today's climate. Here the original and revised morphologies are presented.

Figure 4. Pity the poor staff artist trying to get a pterosaur correct in today’s climate. Here the original and revised morphologies are presented. Digit 5 need to go to the outside of a large foot and the tail is short.

Perhaps hoping to support the invalid archosaur origin of pterosaurs hypothesis,
Britt et al report the margin of an antorbital fenestra bears a remnant of a fossa. We looked at a similar interpretation earlier when Nesbitt and Hone 2010 attempted to pull a Larry Martin with that single trait from Dimorphodon. Thankfully, Britt et al. did not attempt to use Euparkeria or any phytosaurs for outgroups. But, regrettably, they didn’t use Cosesaurus either (Fig. 5). Avoiding further controversy, they left the basalmost node generic: “Pterosauria”.

Addendum: checking the SuppMat .nex file,
I see they employed the tritiosaur lepidosaur, Macrocnemus, and two large archosauriforms, Postosuchus and Herrerrasaurus for outgroup taxa. That still does not get you very far based on the verified and validated taxa listed below. Neither Postosuchus nor Herrerasaurus are related to Macrocnemus and pterosaurs.

Figure 5. Basal pterosaurs in the LPT.

Figure 5. Basal pterosaurs and their outgroups in the LPT.

Late addendum
Adding Caelestiventus to the LPT nests it basal to the Dimorphodon clade, not with Dimorphodon.

Figure 1. Maxilla, nasal and jugal of Caeletiventus, plus full mandible.

Figure 1. Maxilla, nasal and jugal of Caeletiventus, plus full mandible casts created by CT scans. Colors added here.

References
Britt BB, Dalla Vecchia FM, Chure DJ, Engelmann GF, Whiting MF, and Scheetz RD 2018. Caelestiventus hanseni gen. et sp. nov. extends the desert-dwelling pterosaur record back 65 million years. Nature Ecology & Evolutiondoi:10.1038/s41559-018-0627-y.
Nesbitt SJ and Hone DWE 2010. An external mandibular fenestra and other archosauriform character states in basal pterosaurs. Palaeodiversity 3: 225–233
Peters D 2011. A Catalog of Pterosaur Pedes for Trackmaker Identification
Ichnos 18(2):114-141. http://dx.doi.org/10.1080/10420940.2011.573605

https://en.wikipedia.org/wiki/Caelestiventus

7 thoughts on “New Triassic basal dimorphodontid: Caelestiventus

  1. The qualifier “first desert pterosaur” in the press release leads to this in USA Today: “…after discovering the pterodactyl’s fossilized remains in northeastern Utah, scientists suggest the creature was the first flying vertebrate on Earth, according to a new study released Monday.
    In fact, the new fossil pushes back the first flying vertebrate by some 65 million years, all the way back into the Triassic period.”

      • What’s garbled here is that the press release said it pre-dated other desert-habitat pterosaurs by 65 million years. The USA Today writer may think this is the only Triassic pterosaur, or they may be reckoning that the earliest known pterosaurs as a group pre-date Archaeopteryx by 65 million..

        An interested reader of USA Today might imagine the first claim: that this was the first pterosaur known from the Triassic. From the text they may even imagine that pterosaurs are some kind of bird..

  2. One more thing: There’s a very short [3 minutes] video on the BYU site showing the discovery site and a bit of the preparation. Since this is largely 3D, they’re leaving quite a bit in the matrix and studying it via tomography. Sounds like critical features, especially the skull and braincase will be available for 3D printing and study by others.

    • re: website. I’ll take your word for it. Correction made. That was a copy/paste from a published source.

      re: wattle. Take a look at any ‘pelican in flight’ photos. That pouch is not to be seen. Somehow it tightens up. The Caelestiventus mandible is quite narrow, so pouch probably out of the question. A large wattle would wiggle/flap in flight, like any loose material would. Not good aerodynamically and irritating to the pterosaur IMHO.

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