Spiekeman and Ezcurra 2026 distort perspectives on the phylogenetic origins of modern reptiles due to taxon exclusion

Sorry. We’re back to the same theme here.
Spiekman and Ezcurra 2026 followed traditional textbooks to produce yet another distortion of reptile phylogeny due to taxon exclusion. I don’t want to call this laziness. Likely these authors are busy with other matters – and they don’t want to overturn what their textbooks report. That would upset their business model: student tuition$ and textbook sale$. So they played it safe.

There is one phylogenetic experiment that minimizes taxonomy exclusion.
The large reptile tree (LRT, 2340 taxa) includes so many more taxa in a wider gamut than any and all of the smaller and more focused prior and current studies in order to minimize the traditional problem of taxon exclusion. Not eliminate. Minimize. Improvements are always possible and welcome.

From the first sentence the authors assume incorrectly.
Like others before them, Spiekman and Ezcurra removed Mammalis from the Reptilia. They didn’t realize, due to taxon exclusion, that Amniota is a junior synonym for Reptilia in the LRT. Silvanerpeton (Fig 1) is the last common ancestor. The first dichotomy split Archosauromorpha from Lepidosauromorpha in 2011. A number of traditional anamniotes (e.g. Gephyrostegus (Fig 1), Chroniosuchus) are primitive members of the Archososauromorpha.

Spiekman and Ezcurra wrote,
“Here, we provide an overview of the current state-of-the-art of the phylogenetic research on the origin of modern reptiles.”

Evidently in an overview you don’t have to actually report on ‘the origin of modern reptiles’, because they don’t.

Figure 2. Eusauropleura to scale with ancestral and descendant taxa including Eucritta, Utegenia, Silvanerpeton and Gephyrostegus, the last common ancestor of all reptiles. ” data-image-caption=”

Figure 2. Eusauropleura to scale with ancestral and descendant taxa including Eucritta, Utegenia, Silvanerpeton and Gephyrostegus, the last common ancestor of all reptiles.

” data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2018/12/gephyrostegus_eusauropleura588.jpg?w=584″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2018/12/gephyrostegus_eusauropleura588.jpg?w=584″ alt=”Figure 2. Eusauropleura to scale with ancestral and descendant taxa including Eucritta, Utegenia, Silvanerpeton and Gephyrostegus, the last common ancestor of all reptiles.” class=”wp-image-34503″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2018/12/gephyrostegus_eusauropleura588.jpg?w=584 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2018/12/gephyrostegus_eusauropleura588.jpg?w=101 101w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2018/12/gephyrostegus_eusauropleura588.jpg?w=202 202w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2018/12/gephyrostegus_eusauropleura588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

The Spiekman and Ezcurra headline is also clickbait.
The only time the authors mention ‘last common ancestor’ is when they quote Motani defining Ichthyosauromorpha. In other words, Spiekman and Ezcurra never ‘get to the root of it’ nor do they discuss‘the phylogenetic origins of modern reptile.’

Remember ‘birds are dinosaurs’?
Under the same phylogenetic reasoning ‘mammals are reptiles’. Spiekman and Ezcurra don’t understand this yet due to taxon exclusion.

In the LRT
the diapsid skull architecture appeared twice by convergence. Spiekman and Ezcurra don’t understand this yet due to taxon exclusion.

The authors reported,
“We are only considering those groups that are generally considered to be crown-group reptiles and their close relatives, meaning that we will not include other reptile-line amniotes, such as captorhinids, bolosaurs, araeoscelids, procolophonomorphs, mesosaurids and millerettids.’

But later in the text the authors could not resist discussing thalattosaurs and ichthyosaurs, which are close relatives of mesosaurids in the LRT. Evidently Spiekman and Ezcurra don’t understand this ‘crown reptile’ thing yet.

In addition, their figure 2 includes a variety of ‘weird’ reptiles not related to crown reptiles. So… Spiekman and Ezcurra have demonstrated they can’t stick to their own parameters.

When you write your own manuscript and set up parameters, try to stay within those.

Yes, the LRT now includes fish and other pre-reptiles. Those are called out-group taxa.

The authors discussed
some of the several published turtle origin hypotheses in broad strokes. None are correct.

For the time and effort the authors put in to reporting the several errors of others as alternative hypotheses they could have become the authorities on turtle origins by simply building their own version of the LRT and reporting results.

This Spiekman and Ezcurra overview was so much wasted effort when real effort was needed to clean up the errors accumulated and reported in this overview.

References
Spiekman SNF and Ezcurra MD 2026. Getting to the root of it: perspectives on the phylogenetic origins of modern reptiles. Journal of Systematic Palaeontology 24(2):2672998

Thanks to reader Sean who brought this paper to my attention.

Source: https://pterosaurheresies.wordpress.com/2026/06/26/spiekeman-and-ezcurra-2026-distort-perspectives-on-the-phylogenetic-origins-of-modern-reptiles-due-to-taxon-exclusion/