svp abstracts of interest or bombast 2024: H–J

It is abstract season.
Here are selected sentences from selected abstracts from SVP 2024 – Minneapolis:

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-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2018/12/gephyrostegus_eusauropleura588.jpg?w=202″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2018/12/gephyrostegus_eusauropleura588.jpg?w=584″ class=”size-full wp-image-34503″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2018/12/gephyrostegus_eusauropleura588.jpg” alt=”Figure 2. Eusauropleura to scale with ancestral and descendant taxa including Eucritta, Utegenia, Silvanerpeton and Gephyrostegus, the last common ancestor of all reptiles.” width=”584″ height=”869″ />

Figure 1. Eusauropleura to scale with ancestral and descendant taxa including Eucritta, Utegenia, Silvanerpeton and Gephyrostegus, the last common ancestor of all reptiles.

Igielman B: The impact of taxonomic representation and “representative taxa”; a novel,
comprehensive phylogenetic analysis of early amniotes.
“the origins of crown Amniota during the Palaeozoic are poorly understood.”

Not true. In the LRT Reptilia = Amniota origins are precise and well understood. Silvanerpeton (Fig 1), the first reptile because it is the last common ancestor of all reptiles in the LRT is commonly omitted from analyses.

“Here I present an expansive, novel phylogenetic analysis (77 taxa, 328 characters) of early tetrapods. I distinctly include near equal taxonomic representation of both stem and early crown amniotes, one of the first analyses to do so.”

The LRT got there first and now includes 2325 taxa.

“I find anthracosaurs in their more traditional position as stem amniotes;”

In the LRT reptilomorphs = anthracosaurs.  Utegenia and Eucritta (Fig 1) are in this grade. In any case, use genera. Beware of the vague hope that suprageneric taxa provide.

“recover a monophyletic Lepospondyli, inclusive of aistopods, as the sister clade to amniotes;”

In the LRT Late Devonian Tulerpeton is also a proximal outgroups
to the Reptilia = Amniota.

“and find microsaurs as a paraphyletic grade with respect to other lepospondyls.”

The LRT recovers microsaurs as a monophyletic clade
apart from frogs and salamanders.

“I recover araeoscelids as stem mammals, an entirely novel hypothesis.”

The LRT refutes that hypothesis.

“suggests that amphibians and amniotes diverged far earlier than previously thought,
and demonstrates that more expansive taxonomic inclusion can have significant
impacts on phylogenetic topologies.”

Your heard that ‘expansive’ methodology here first. In the LRT the frog/reptile split occurred prior to the end of the Late Devonian with Tulerpeton.

Figure 1. Click to enlarge. Gephyrostegus moves to the base of the Archosauromorpha with its long-legged, hump-backed relatives. ” data-image-caption=”

Figure 1. Click to enlarge. Gephyrostegus moves to the base of the Archosauromorpha with its long-legged, hump-backed relatives.

” data-medium-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2021/11/basal-amniotes-to-scale588-1.jpg?w=300″ data-large-file=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2021/11/basal-amniotes-to-scale588-1.jpg?w=584″ class=”size-full wp-image-62509″ src=”https://pterosaurheresies.wordpress.com/wp-content/uploads/2021/11/basal-amniotes-to-scale588-1.jpg” alt=”Figure 1. Click to enlarge. Gephyrostegus moves to the base of the Archosauromorpha with its long-legged, hump-backed relatives.” width=”584″ height=”580″ />

Figure 2. Click to enlarge. Gephyrostegus moves to the base of the Archosauromorpha with its long-legged, hump-backed relatives.

Jenkins KM et al: Taxon selection influences tree topology in the early evolution of Amniota.

“The basal dichotomy within Amniota (mammals and reptiles) was recognized early
in the history of phylogenetic systematics, and with it developed a canonical
understanding of the evolutionary relationships of basally branching clades.”

In the LRT the basal dichotomy splits Lepidosauromorpha (which includes turtles) from Archosauromorpha, which includes mammals). Add taxa to test this.

“To bring clarity to this ongoing debate of the early evolution of amniotes, I compiled a
large and taxonomically comprehensive phylogenetic dataset encompassing all major
recognized clades of early crown amniotes and stem and crown reptiles.”

Sounds like the goal and method of the LRT.

“This includes 590 fully illustrated characters and 150 taxa representing all the major clades of ‘pelycosaurian’ stem mammals and stem reptiles, along with several outgroups.”

Sounds like too few taxa, too many characters.

“the inclusion and exclusion of taxa has a major effect on overall topology.”

Working with the LRT, I can confirm that result.

“To properly assess the evolutionary relationships of early amniotes, and likely most extinct clades, increased taxon sampling is necessary, particularly if assessing macroevolutionary patterns.”

The LRT confirms that conclusion.