Are pterosaurs really just archosaurs close to dinosaurs? The myth revealed!

You’ve heard it reported,
“pterosaurs are not dinosaurs, but both are archosaurs and closely related.”

Note: whenever academics say this, they never show this.

That oversight is remedied today
with a graphic of the basal dinosaur, Herrerasaurus, shown (Fig 1) alongside the basal pterosaur, Austriadactylus, which Pegas 2025 considered closely related outgroup and ingroup taxa in their ‘most comprehensive pterosaur cladogram to date’.

Whenever you hear such bombast, watch out! It’s almost never true.

The pertinent portion of the Pegas 2025 cladogram is also shown here (Fig 1).

Figure 2 updated. Here is the dentary of Lagerpeton to scale with the skull of Tropidosuchus, both proterochampsids in the LRT. ” data-image-caption=”

Figure 2 updated. Here is the dentary of Lagerpeton to scale with the skull of Tropidosuchus, both proterochampsids in the LRT.

” data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/07/lagerpeton588.jpg?w=558″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/07/lagerpeton588.jpg?w=558″ alt=”Figure 2 updated. Here is the dentary of Lagerpeton to scale with the skull of Tropidosuchus, both proterochampsids in the LRT.” class=”wp-image-93581″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/07/lagerpeton588.jpg?w=558 558w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/07/lagerpeton588.jpg?w=82 82w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/07/lagerpeton588.jpg?w=163 163w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/07/lagerpeton588.jpg 588w” sizes=”(max-width: 558px) 100vw, 558px” />

Since pterosaurs have recently been compared to lagerpetids,
I also include Lagerpton (Figs 1, 2) for comparison. Related, but rarely mentioned Tropidosuchus is shown here (Fig 2). Tiny hands. Bipedal in some species. Scrappy Ixalerpeton and even scrappier Venetoraptor are also shown (Fig 3). These nest with Prolacerta.

Pedal digit 5 is missing
in the dinosaur and lagerpetid. Manual digit 4 is tiny in the dinosaur… so shouldn’t we be looking for an outgroup clade that has a long toe five and long finger four? (Fig 4).

Such taxa with a longer list of pterosaur synapomorphies
were published 26 years ago and largely ignored ever since.

Huxley and Ostrom know that paleontologists take a long time to warm up to new ideas.

This topic arose
because Nascimento et al 2026 borrowed their cladogram from Pegas 2025. So these mistakes are going viral and need to be nipped in the bud. I’ve been in email contact with young Nascimento. Hopefully he will test earlier traditions and not fall in with the party line.

But that may be at his peril. We’ll see what happens next.

References
Nascimento AS et al 2026. First evidence of a mandibular crest in Brasileodactylus Kellner, 1984 (Pterosauria, Pteranodontoidea, Anhangueridae), with comments on pterosaur headcrests. The Anatomical Record. https://doi.org/10.1002/ar.70364
Pêgas RV 2025. On the systematics and phylogenetic nomenclature of the Ornithocheiriformes (Pterosauria, Pteranodontoidea). Palaeontologia Electronica, 28(2):a25. https://doi.org/10.26879/20
Peters D 2000a. Description and Interpretation of Interphalangeal Lines in Tetrapods.  Ichnos 7:11-41.
Peters D 2000b. A Redescription of Four Prolacertiform Genera and Implications for Pterosaur Phylogenesis. Rivista Italiana di Paleontologia e Stratigrafia 106 (3): 293–336.

Comments on Pegas 2025 here: https://pterosaurheresies.wordpress.com/…/pegas-2025…/

More parsimonious pterosaur outgroup taxa identified 26 years ago here: https://pterosaurheresies.wordpress.com/…/what-exactly…/

Source: https://pterosaurheresies.wordpress.com/2026/10/27/are-pterosaurs-really-just-archosaurs-close-to-dinosaurs-the-myth-revealed/