Three basic mistakes in a new dino origin paper

Marsola and Langer 2019
are trying their best to rely on traits to define dinosaurs and their outgroups. This is always a mistake. The last common ancestor method is the only one that works. Otherwise you risk ‘Pulling a Larry Martin‘.

Marsola and Langer 2019
also rely on previously published cladograms without testing which one, if any, is the best. This is also always a mistake. It’s not that difficult to find fault with cladograms like these… or to build your own. After all, they are scientists. That is their job. Don’t blindly accept the work of others. Test it.

Marsola and Langer 2019
also exclude taxa that, if added, would radically change these cladograms. Taxon exclusion is also always a mistake. It’s not that difficult to add taxa. I do it every week.

Figure 1. Three cladograms from Marsola and Langer 2019, essentially copied from other sources and more or less trusted despite their differences.

Figure 1. Three cladograms from Marsola and Langer 2019, essentially copied from other sources and more or less trusted despite their differences.

Why waste the readers’ time with invalid cladograms?
The large reptile tree (LRT, 1530 taxa) has been online for several years. The taxa therein (from fish to birds) can be used along with any character list in your collection.

In the meantime,
we looked at dinosaur origins years ago here along with an illustration of the pertinent taxa below (Fig. 2).

Figure 2. The origin of dinosaurs to scale. Gray arrows show the direction of evolution. This image includes Decuriasuchus, Turfanosuchus, Gracilisuchus, Lewisuchus, Pseudhesperosuchus, Trialestes, Herrerasaurus, Tawa and Eoraptor.

Figure 2. The origin of dinosaurs to scale. Gray arrows show the direction of evolution. This image includes Decuriasuchus, Turfanosuchus, Gracilisuchus, Lewisuchus, Pseudhesperosuchus, Trialestes, Herrerasaurus, Tawa and Eoraptor.

Why do paleontologists not test new hypotheses?
Good question. Is it because they are employed as teachers who run the risk of informing their students that assigned textbooks are out-of-date in small or large part? Is it because they want to be the ones to announce a paradigm shift from their own studies? Is it because they risk the ire of colleagues who are also teachers with their own textbooks? Is it really, when you get down to it, all about money? Reputation? Sticking one’s head in the sand (= maintaining an invalid status quo) is always a mistake.


References
Marsola JC de A and  Langer MC 2019. Dinosaur Origins. Reference Module in Earth Systems and Environmental Sciences 2019
doi: https://doi.org/10.1016/B978-0-12-409548-9.11846-9

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