SVP 2025 abstracts of interest 4

It’s SVP abstracts season~!
Here is post 4 of 10.

On the origin of nightjars (Caprimulgidae): perspectives from the fossil record

Chen and Field (p172)
“The fossil record of the avian clade Strisores (which includes nightjars, oilbirds, potoos, frogmouths, owlet-nightjars, treeswifts, swifts, and hummingbirds) has been richly documented by avian standards.”

In the LRT hummingbirds nest with stilts in the LRT, not frogmouths and owlets (Fig 1). The rest are related to owls, nightjars and owlets.

“new fossil descriptions and restudy of previously known specimens, together with findings from recent phylogenomic studies, have started to provide insight into nightjar evolutionary history”

The LRT nests nightjars and owlets with similar owls (not listed in the abstract).

“a dataset of 117 characters scored for 30 taxa (including 16 fossil members of Strisores).

The LRT tests more characters and more taxa.

“Maximum parsimony analyses with extant taxa constrained to a molecular scaffold recovered some trees in which archaeotrogonids were positioned as stem-group nightjars, but also others in which they were placed on the stem leading to Daedalornithes (owlet-nightjars and apodiforms) or outside of crown-group Strisores.”

First run a wide-gamut phenomic analysis. Then apply suprageneric labels.

3D visualization of the chondrocytes and osteoblasts repairing the gastralia in the structurally preserved skin of a new Devonian stem tetrapod.

Chen et al (p173)
“Gastralia is an innovation of tetrapods. However, in extant tetrapods, gastralia are only maintained in crocodilians and tuatara.”

Basal tetrapods, like Greererpeton don’t have gastralia, but Pholidogaster (Fig 2) appears to have gastralia – but are they homologs?

According to Wikipedia, “Gastralia were ancestrally present in amniotes, but have been lost in many groups.” In the LRT Silvanerpeton is the last common ancestor of all reptiles = amniotes – and it has gastralia.
wiki/Gastralia

In the LRT the most primitive taxon with gastralia is the reptilomorph Balaenerpeton (Fig 3), also one of the first taxa in the lineage of reptiles to have five fingers.
The thumb is the newest digit.

“The evolution and development of gastralia thus remain elusive.”

Not elusive in the LRT. We looked at the origin, disappearance and reappearance in the LRT here in 2021.

“A new near complete Devonian stem tetrapod with soft tissues preserved at the cellular-level fidelity was recently discovered in Greenland. Its skin exhibits multiple cornified layers, resembling amniote skin rather than lissamphibian skin.”

“The fragile scales and the solid gastralia, the ventral ‘floating skeletal elements’, are both kept by the belly skin. The rounded scales resembling modern caecilian scales are superficial to the elongated gastralia.”

“This falsifies the idea that round-oval scales on the flanks of early tetrapods would become elongated at the ventral side of the body and evolve into gastralia.”

That makes sense. Scales are dermal. Gastralia are sub-dermal.

“It indicates that gastralia are mineralized via metaplastic ossification, which is known to occur in the formation of reptile osteoderms, rather than dermal or endochondral ossification. The presence of dense connective tissue is the prerequisite for metaplastic bone development,which suggests that stem tetrapods already have a reptile-like dense dermis.”

The question is how close to Pholidogaster and/or Balanerpeton is the new taxon with gastralia described by Chen et al in this abstract.

Amniote traits and terrestriality in an early Amphibian

Coates et al (p186)
“Eugyrinus wildi is among the oldest temnospondyl amphibians in the fossil record. The team went back to look for more and results matched expectations.”

Eugyrinus was not tested in the LRT, so it was added to the LRT. Eugyrinus was recovered as one of the basal microsaurs alongside Kirktonecta.

In the LRT microsaurs are derived from basalmost Lissamphibians,
which are derived from basalmost dissorophids,
which are derived from basalmost dendrerpetonids,
which are derived from basalmost temnospondyls.
So rapid radiation applies to all these clades during the Late Devonian based on the presence of Tulerpeton a derived reptilomorph recovered from Latest Devonian strata.

Since the authors don’t mention this… Eugyrinus is Westphalian, 315-308mya, Middle to Late Carboniferous.

“Computed tomography revealed barely disturbed articulated limbs with long, slender, hooked terminal phalanges signaling the likely presence of claws. Furthermore, the limb proportions match those of lepospondyls (putative stemamniotes), the finely textured dorsal coverage of tiny scales in packed rows is decidedly lizardlike, and yet the skull, as previously reported, bears lateral line pits and grooves.”

(See prior paragraph about clades and Tulerpeton.)

“None of these discoveries excludes Eugyrinus from the Temnospondyli, but claw presence implies enhanced keratinization, previously considered a marker of amniote affinity. Additionally, this early amphibian also reveals a three dimensionally preserved eye and diagnosable gut contents.”

All of these traits could be convergent. The last common ancestor method is the ONLY method that should be used to determine taxon and clade interrelationships.

To their credit, the team reported:

“we suggest (1) that clawed trackways are not the secure markers of amniote track-makers that they formerly were, (2) that Eugyrinus corroborates current and recent hypotheses that integument keratinization was widespread among early crown-group tetrapods, and (3) that the enhanced environmental tolerance conferred by this innovation (emerging within the stem lineage) likely contributed to individual survivorship in water-to-land transitions as well as lineage survivorship through the end Devonian biotic crises.”

Unique early-diverging pachycormid fish (Pachycormiformes) elucidates the origins and early evolutionary history of the group

Cooper and Maxwell (p191)
“Euthynotus (Fig 5) represents the earliest-diverging and most morphologically primitive pachycormid, represented by abundant Toarcian-aged (Early Jurassic) specimens.”

Not in the LRT.

“Although generally optimized near the base of Teleosteomorpha, the sister-group relationships of Pachycormiformes are less well resolved. Examination of referred materials reveals that this genus instead likely represents a grade of several distinct taxa.”

Well resolved in the LRT.

“One of these, a unique genus and species with clear pachycormid synapomorphies including a toothed rostrodermethmoid contributing to the oral margin and falciform pectoral fin, additionally shows several primitive character states that have been lost in both Euthynotus and more derived pachycormids.”

That possible new genus “with clear pachycormid synapomorphies”
is not named in the abstract.

“Phylogenetic analysis places the new taxon in an unresolved relationship with Euthynotus at the base of Pachycormiformes.”

Not in the LRT.

Exploring the aerodynamic impact of the head crest in Tupuxuara leonardii (Pterosauria)

Costa et al. (p195).
“Here we investigated the influence of the cranial crest on the aerodynamics of the Brazilian pterosaur Tupuxuara leonardii. Using IMCF 1052 images for photogrammetry, a 3D skull reconstruction was performed, and three geometries were modeled: without a crest (TMIN), based on the preserved fossil (TMED),and with the maximum estimated crest size (TMAX). These models were constructed to allow a comparative analysis. Computational Fluid Dynamics (CFD) simulations were performed.”

“Computational aerodynamic analyses of T. leonardii skulls indicate that crest morphology significantly affects flight performance.”

“At low angles of attack (0º–10º), drag increases gradually due to organized airflow, whereas angles above 20º lead to a sharp rise in drag caused by flow detachment. “a stall occurs near 20º.”

“Results showed that the crest indeed has an aerodynamic influence and may exert a biomechanical function similar to that of a directional rudder during flight.”

Sometimes science brings new insight into what seems obvious. Not this time.

Source: https://pterosaurheresies.wordpress.com/2025/11/18/svp-2025-abstracts-of-interest-4/