Caecilian updates explained with standard DGS colors

Caecilians are extant, legless ‘amphibians’
not related to frogs and salamanders in the LRT.

Figure 1. Early Jurassic Eocaecilia from Jenkins and Walsh 1993, updated with standard DGS colors.

Yesterday,
caecilians (Figs 1, 2) briefly nested with basal tetrapods in the large reptile tree (LRT, 2330 taxa) based on the addition to Ninumbeehan.

That lasted less than an hour or so.

Ironically,
rescoring caecilians based on (= biased on) a basal tetrapod (= Ninumbeehan) Bauplan moved them away from Ninumbeehan and back to Microsauria, where caecilians originally nested in the LRT.

Stranger things have happened.

BTW, this addition also moved snakes back to geckos, away from Gila monsters.
That’s what I mean by strange. Parts of the LRT are fragile like that.

Figure 2. Dermophis, the extant Mexican caecilian, is a living microsaur. Here it is updated with standard DGS colors.

There’s one more thing…
Two taxa that previously nested apart in the LRT and elsewhere, Late Triassic Chinlestegophis and Early Permian Tersomius (Fig 3), now nest together in the LRT. In Tersomius the former prefrontal is now the anterior postfrontal (orange). The upraised orbit is the middle postfrontal. The former lacrimal is now the prefrontal (brown) as in Chinlestegophis. 

Figure 1. Chinlestegophis now nests with Tersomius in the LRT. Here both are updated with standard DGS colors. ” data-image-caption=”

Figure 1. Chinlestegophis now nests with Tersomius in the LRT. Here both are updated with standard DGS colors.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/01/chinlestegophis.tersomius.skull588.jpg?w=233″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/01/chinlestegophis.tersomius.skull588.jpg?w=584″ class=”size-full wp-image-90854″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/01/chinlestegophis.tersomius.skull588.jpg” alt=”Figure 1. Chinlestegophis now nests with Tersomius in the LRT. Here both are updated with standard DGS colors. ” width=”584″ height=”752″ srcset=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/01/chinlestegophis.tersomius.skull588.jpg?w=584&h=752 584w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/01/chinlestegophis.tersomius.skull588.jpg?w=117&h=150 117w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/01/chinlestegophis.tersomius.skull588.jpg?w=233&h=300 233w, https://pterosaurheresies.wordpress.com/wp-content/uploads/2025/01/chinlestegophis.tersomius.skull588.jpg 588w” sizes=”(max-width: 584px) 100vw, 584px” />

Figure 1. Chinlestegophis now nests with Tersomius in the LRT. Here both are updated with standard DGS colors.

As reported by Marjanović et al 2024,
“Chinlestegophis was argued to link extant caecilians to Permo-Triassic stereospondyl temnospondyls rather than to frogs and salamanders (and through them to amphibamiform temnospondyls or to brachystelechid and lysorophian “lepospondyls”).”

According to the LRT, other microsaurs separate caecilians from other amphibians and basal tetrapods.

References
Case EC 1910. New or little known reptiles and amphibians from the Permian (?) of Texas. Bulletin of the American Museum of Natural History 28, 163–181.
Jenkins FA and Walsh M 1993. An Early Jurassic caecilian with limbs. Nature 365: 246–250.
Jenkins FA, Walsh DM and Carroll RL 2007. Anatomy of Eocaecilia micropodia, a limbed caecilian of the Early Jurassic. Bulletin of the Museum of Comparative Zoology 158(6): 285-366.
Maddin H, Fröbisch NB, Evans DC and Milner AR 2013. Reappraisal of the Early Permian amphibamid Tersomius texensis and some referred material. Comptes Rendus Palevol 12:447-461.
Marjanovic D, Maddin, HC, Olori JC and Laurin M 2024. The new problem of Chinlestegophis and the origin of caecilians (Amphibia, Gymnophionomorpha) is highly sensitive to old problems of sampling and character construction. Fossil Record. 27 (1): 55–94.
Pardo JD, Small BJ and Huttenlocker AK. 2017, Stem caecilian from the Triassic of Colorado sheds light on the origins of Lissamphibia. PNAS: 7 pp. www.pnas.org/cgi/doi/10.1073/pnas.1706752114
Peters WCH 1880 “1879”. Über die Eintheilung der Caecilien und insbesondere über die Gattungen Rhinatrema und Gymnopis. Monatsberichte der Königlichen Preussische Akademie des Wissenschaften zu Berlin 1879: 924–945.
Wake MH 1980. Reproduction, growth, and population structure of the central American caecilian Dermophis mexicanus. Herpetologica: 244-256.

wiki/Eocaecilia
wiki/Dermophis
wiki/Tersomius
wiki/Chinlestegophis