Growth pattern of a new large Romualdo pterosaur

Bantim et al. 2020 document
a new “pteranodontoid pterosaur with anhanguerid affinities (MPSC R 1935) from the Romualdo Formation (Lower Cretaceous, Aptian-Albian), is described here and provides one of the few cases where the ontogenetic stage is established by comparison of skeletal fusion and detailed osteohistological analyses.”

Figure 1. Excellent wing finger carpophalangeal joint from the Bantim et al. 2020 paper. Note the unfused sesamoid (extensor tendon process), a phylogenetic trait of lepidosaurs, not an ontogenetic trait of archosaurs, as phylogenetic analysis documents.

Figure 1. Excellent wing finger carpophalangeal joint from the Bantim et al. 2020 paper. Note the unfused sesamoid (extensor tendon process), a phylogenetic trait of lepidosaurs, not an ontogenetic trait of archosaurs, as phylogenetic analysis documents.

Continuing from the abstract
“The specimen … consists of a left forelimb, comprising an incomplete humerus, metacarpal IV, pteroid and digits I, II, III, IV, including unguals. This specimen has an estimated maximized wingspan of 7.6 meters, and despite its large dimensions, is considered as an ontogenetically immature individual. Where observable, all bone elements are unfused, such as the extensor tendon process of the first phalanx and the carpal series. The absence of some microstructures such as bone resorption cavities, endosteal lamellae, an external fundamental system (EFS), and growth marks support this interpretation. Potentially, this individual could have reached a gigantic wingspan, contributing to the hypothesis that such large flying reptiles might have been abundant during Aptian-Albian of what is now the northeastern portion of Brazil.”

Anhanguera

Figure 2. Anhanguera.

By comparison,
coeval Anhanguera has a 4.6m (15 ft) wingspan. The largest complete ornithocheirid, SMNK PAL 1136 has a 6.6m wingspan.

Bone elements fuse and lack fusion
in phylogenetic patterns (rather than ontogenetic patterns) in the clade Pterosauria, as documented earlier here in 2012. That is why you can’t keep pretending pterosaurs are archosaurs and not expect problems like this to accumulate. Your professors are taking your time and money and giving you invalidated information.

Figure 5. Largest Pteranodon to scale with largest ornithocheirid, SMNS PAL 1136.

Figure 5. Largest Pteranodon to scale with largest ornithocheirid, SMNS PAL 1136.

It is a continuing black mark on the paleo community
that pterosaurs continue to be considered archosaurs by paid professionals when phylogenetic analysis (and Peters 2007 and the LRT) nests pterosaurs with lepidosaurs. That is why pterosaurs have lepidosaur phylogenetic fusion patterns (Maison 2002, 2002) distinct from archosaur ontogenetic fusion patterns. Just add taxa colleagues. The pterosaur puzzle piece does not fit into the archosaur slot… everyone admits that. The pterosaur puzzle piece continues to fit perfectly and wonderfully in the fenestrasaur tritosaur lepidosaur slot.


References
Bantim RAM et al. (5 co-authors) 2020. Osteohistology and growth pattern of a large pterosaur from the lower Cretaceous Romualdo formation of the Araripe basin, northeastern Brazil. Science Direct https://doi.org/10.1016/j.cretres.2020.104667
Maisano JA 2002. The potential utility of postnatal skeletal developmental patterns in squamate phylogenetics. Journal of Vertebrate Paleontology 22:82A.
Maisano JA 2002.
Terminal fusions of skeletal elements as indicators of maturity in squamates. Journal of Vertebrae Paleontology 22: 268–275.
Peters D 2007. 
The origin and radiation of the Pterosauria. In D. Hone ed. Flugsaurier. The Wellnhofer pterosaur meeting, 2007, Munich, Germany. p. 27.

https://pterosaurheresies.wordpress.com/2013/05/14/phylogenetic-fusion-patterns-in-pterosaurs/

Flugsaurier 2018: ‘Young istiodactylid’ nests with tall pterodactylids in the LPT

Flugsaurier 2018 opens today, August 10,
and the abstract booklet is out. So it’s time to take a look at some of the news coming out of that Los Angeles pterosaur symposium. Since the purpose of the symposium is increase understanding of pterosaurs, I hope this small contribution helps.

Figure 1. The Erlianhaote specimen attributed by Hone and Xu 2018 to istiodactylidae nests in the LPT with the large derived pterodactylids.

Figure 1. The Erlianhaote specimen attributed by Hone and Xu 2018 to the clade Istiodactylidae (within Ornithocheiridae) nests in the LPT with the large derived pterodactylids. Note the un-warped deltopectoral crest and lack of a deep cristospine, along with the long legs and short wings.

Hone and Xu at Flugsaurier 2018
describe, “An unusual and nearly complete young istiodactylid from the Yixian Formation, China (Fig. 1). The specimen shows the characteristic istiodactylid cranial features of tooth shape and enlarged nasoantorbital fenestra. However, it has proportionally large hindlimbs and wing proportions that are similar to those of azhdarchids. This has led to suggestion that the specimen may be a composite and that only the cranial material is istiodactylid. Preparation work around some key parts revealed no inconsistencies in the matrix or evidence of glue. The specimen is held in the Erlianhaote Dinosaur Museum, Erlianhote, China.”

Figure 2. The Erlianhaote specimen nests with these pterodactylids in the LPT, not with Istiodactylus (Fig. 3). Compare to valid istiodactylids in figures 4–6/

Figure 2. The Erlianhaote specimen nests with these pterodactylids in the LPT, not with Istiodactylus (Fig. 3). Compare to valid istiodactylids in figures 4–6/

Reconstructed as is
(Fig. 2) and added to the large pterosaur tree (LPT, 233 taxa, not yet updated due to no museum number nor genus name) the young ‘istiodactylid’ nests as a large derived pterodactylid. 13 steps separate this taxon from the Istiodactylus clade.

Ornithocheirids,
like Istiodactylus (Figs. 3, 4) and the SMNL PAL 1136 specimen (Fig. 5), share a very large wing finger, a short metacarpus, a warped deltopectoral crest, small free fingers and deeply keeled sternal complex not found in the Erlianhote specimen.

Figure 3. Istiodactylus has a shorter neck, longer wing finger and deep cristospine, among other traits not found in the new Erlianhaote specimen.

Figure 3. Istiodactylus has a shorter neck, longer wing finger and deep cristospine, among other traits not found in the new Erlianhaote specimen.

Figure 4. Istiodactylus sinensis is an istiodactylid from China sharing few traits with the new Erlianhaote specimen. Note the warped deltopectoral crest not warped in the new specimen.

Figure 4. Istiodactylus sinensis is an istiodactylid from China sharing few traits with the new Erlianhaote specimen. Note the warped deltopectoral crest not warped in the new specimen. Manual 4.1 is shorter than in other well-known istiodactylids.

The largest ornithocheirid

Figure 5. The unnamed largest ornithocheirid, SMNK PAL 1136, nests with Istiodactylus.

Figure 6. The Erlianhaote pterodactylid reconstructed in several views.

Figure 6. The Erlianhaote pterodactylid reconstructed in several views. The imagined (gray) areas of the skull here were imagined as an istiodactylid, but the better restoration is shown in figure 2.

It’s better not to eyeball certain specimens.
Sometimes you have to run them through a phylogenetic analysis to find out what they are. That’s what the LPT is for. It minimizes taxon exclusion and handles convergence.

Pterosaurs are still lepidosaurs.
So they follow lepidosaur fusion patterns, which follow phylogeny. Hone and Xu made the mistake of imagining pterosaurs might have archosaur fusion patterns that follow ontogeny.

Why am I not at Flugsaurier 2018?
In addition to about a dozen reasons that I can list later, or your can guess now, I can be more helpful and timely here.

References
Andres B and Ji Q 2006. A new species of Istiodactylus (Pterosauria, Pterodactyloidea) from the Lower Cretaceous of Liaoning, China. Journal of Vertebrate Paleontology, 26: 70-78.
Bowerbank JS 1846. On a new species of pterodactyl found in the Upper Chalk of Kent P. giganteus). Quarterly Journal of the Geological Society 2: 7–9.
Bowerbank JS 1851. On the pterodactyles of the Chalk Formation. Proceedings of the Zoological Society, London, pp. 14–20 and Annals of the Magazine of Natural History (2) 10: 372–378.
Bowerbank JS 1852. On the pterodactyles of the Chalk Formation. Reports from the British Association for the Advancement of Science (1851): 55.
Hone DWE and Xu 2018. An unusual and nearly complete young istiodactylid from the Yixian Formation, China. Flugsaurier 2018: the 6th International Symposium on Pterosaurs. Los Angeles, USA. Abstracts: 53–56.
Hooley RW 1913. On the skeleton of Ornithodesmus latidens. An ornithosaur from the Wealden shales of Atherfield (Isle of Wight)”, Quarterly Journal of the Geological Society, 69: 372-421
Howse SCB, Milner AR and Martill DM 2001. Pterosaurs. Pp. 324-335 in: Martill, D. M. and Naish, D., eds. Dinosaurs of the Isle of Wight, The Palaeontological Association
Wang X, Rodrigues T, Jiang S, Cheng X and Kellner AWA 2014. An Early Cretaceous pterosaur with an unusual mandibular crest from China and a potential novel feeding strategy. Scientific Reports 4 : 6329, pp. 1-9. | DOI: 10.1038/srep06329
Witton MP 2012. New Insights into the Skull of Istiodactylus latidens (Ornithocheiroidea, Pterodactyloidea). PLoS ONE 7(3): e33170. doi:10.1371/journal.pone.0033170

wiki/Istiodactylus