Animated chronology of basal tetrapods

An animated color-coded cladogram
(Fig. 1, subset of the large reptile tree) of basal tetrapods demonstrates a great Devonian radiation prior to the multiple convergent reduction in digit numbers that typify most tetrapods. And perhaps suggests a multiple origination for land-living tetrapods (i.e. metoposaurs and eryopids appear to have had different basal tetrapod ancestors than frogs and reptiles).

  1. Late Devonian – deep blue
  2. Early Carboniferous – light green
  3. Late Carboniferous – deep green
  4. Early Permain – light orange
  5. Late Permian – dark orange (brown)
  6. Early Triassic – pink
  7. Late Triassic – red
  8. Jurassic – cyan
  9. Post-Jurassic to extant – black
Figure 1. Subset of the LRT focusing on basal tetrapods.

Figure 1. Subset of the LRT focusing on basal tetrapods. Six frames change every 2 seconds. 

The cladogram also supports
the reptilian identification of Tulerpeton giving rise to the large number and radiation of Viséan (early Carboniferous) and later reptiles.

Note also
the radiation of derived legless microsaurs also from the Viséan (340 mya).

What you don’t see in this cladogram
are the many short ghost lineages of basal and other taxa implied by the presence of derived taxa known from earlier sediments. Of course, this is due to the somewhat random and certainly rare preservation and excavation of vertebrate fossils.

Even so
the general order of appearance of taxa in the cladogram seems to be correlated to phylogenetic relationships. Exceptions arise due to the random nature of fossil discovery. Give us another 200 years and see how the tree fills out!

Here, once again,
colorizing the taxa and putting them into an animated cladogram increases global understanding of basal tetrapod interrelationships that cannot be communicated in traditional print media.

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2 thoughts on “Animated chronology of basal tetrapods

  1. And perhaps suggests a multiple origination for land-living tetrapods (i.e. metoposaurs and eryopids appear to have had different basal tetrapod ancestors than frogs and reptiles).

    Huh? All metoposaurs were fully, obligatorily aquatic. (The allegedly terrestrial Apachesaurus is turning out to be a misinterpreted baby.) They weren’t even able to walk, at most to slide along on their bellies.

    You still haven’t explained what your “Seymouria tadpole” is supposed to be (Discosauriscus???). Also, as I’ve also told you before, Lysorophus is a nomen dubium known from two and a half undiagnostic vertebrae; all other material that has been called Lysorophus at various times has been called Brachydectes since 1991.

  2. re: Metoposaurs – just because they nest as tetrapods does not mean they have to be terrestrial. Fully aquatic tetrapods are rather common.
    re: Seymouria tadpole – Discosauriscus is not included in the LRT. That it nests with Makowskia rather than Seymouria evidently shows some sort of relationship, perhaps an incidence of neotony.
    re: Lysorophus – thanks for the update.

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