svp abstracts of interest or bombast 2024: A–B

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

Andell J et al: A preliminary exploration of proximal ulna shape in extant mammals and reptiles: implications for fossil tetrapod posture.
“The forelimb posture of fossil tetrapods such as dinosaurs and non-mammal synapsids
has been difficult to reconstruct.”

This is bombastic. Posture is determined from bones and matching tracks.

Angielczyk, KD: Changing perspectives on the synapsid evolutionary radiation and the evolution of mammals.
“I propose a new conceptual model for synapsid evolution: a series of temporally-successive evolutionary radiations that each explored significant volumes of ecomorphological space, instead of a simple trend towards mammals.”

This ‘conceptual model’ is confirmed by the large reptile tree (LRT) and the therapsid skull tree (TST), so this is not news.

Armour Smith E and Sidor CA: Four legs good, two legs better? Investigating if limb allometry supports an ontogenetically driven locomotor mode shift in a skeletally immature assemblage of shuvosaurids (Paracrocodylomorpha: Poposauroidea) from the Upper Triassic Chinle Formation of Petrified Forest National Park.
“Bipedality has evolved convergently in both ornithodiran and pseudosuchian archosaurs
and has important functional, evolutionary, and ecological implications.”

In the LRT shuvosaurids are poposaurs, the sister clade of dinosaurs… so bipedality is a shared trait with one last common ancestor.
Meanwhile… ‘Ornithodira’ and ‘Pseudosuchia’ are polyphyletic clades in the LRT.

Baumgart SL et al: How special are pterosaurs? Comparing cross-sectional structure of pterosaur humeri to that of birds.
“Powered flight has evolved in archosaurs multiple times, first in pterosaurs and then at
least once in birds.”

Pterosaurs are lepidosaurs. We’ve known that since Peters 2007.

“We added pterosaur humeri to our analyses to see what happens in flying archosaurs
larger than modern birds, including one of the largest known pterosaurs, Quetzalcoatlus
northropi, estimated to have had a body mass between 200-300kg.”

Quetz was flightless.That’s how it got so large, as in the largest birds.

“This indicates that pterosaurs had an internal humeral structure different than birds, likely to accommodate the increased stresses of quadrupedal stance and powered flight experienced by their much larger body sizes.”

Pterosaurs were all able to stand bipedally. Some quadrupedal pterosaurs were the size of houseflies. This abstract suffers from taxon exclusion and old myths.

Bloch JI et al: Cranial anatomy of Phenacolemur pagei (Paromomyidae, Euarchonta, Mammalia)from the late Paleocene of northwestern Wyoming.
“A previously described well-preserved skull (USNM 421608) of the paromomyid Ignacius graybullianus from the early Eocene of Wyoming is often used as a model for the family when evaluating anatomy and relationships in the context of early primate evolution.”

In the LRT Ignacius (Fig 1) and kin are basal to the aye-aye, Daubentonia, and these two are apart from primates, closer to arboreal apatemydis, multituberculates and rodents, all forming a second radiation of placentals derived from a Jurassic version of extant Dactylopsila (Fig 1).

Bogner E et al: Hunting for an answer: new insights on the predatory ecomorphology of Borophagus.
“As borophagines evolved, their skulls exhibit morphological traits convergent with those of hyaenids and later-diverging genera, such as Borophagus, are oftenreferred to as bone–cracking dogs.”

In the LRT Borophagus is a sister to the hyaena, Crocuta and the wolf, Canis. So similar traits here are homologs, not convergences.

“A perceived lack of suitable modern analogs makes reconstruction of Borophagus’ predatory ecomorphology difficult.”

Use hyaenas and wolves in analysis for confirmation, modification or refutation.

Bohus CP e al: Description of the southern Illinois colosteid braincase via x-ray computed
tomography.
“Colosteids, such as Greererpeton burkemorani, are well described in the literature.”

In the LRT Colosteus (Fig 2) nests several nodes apart from Greererpeton.

Brand NA et al: Phylogenetic analysis of stem, toothed mysticetes and their relationships to archaeocetes and odontocetes.
“The split between the mysticetes and odontocetes, together forming the Neoceti, is
one of the most consistently supported phylogenetic hypotheses in cetacean evolution.”

In the LRT, mysticetes and odontocetes had separate ancestors going back to arboreal placentals in the Mesozoic. Adding taxa (see the LRT, Fig 3) will help here.

“While extant mysticetes are edentulous as adults, many representatives of this group traditionally recovered outside of crown Mysticeti possess large, multicusped teeth reminiscent of those seen in early odontocetes and basilosaurid archaeocetes.”

In the LRT those taxa are pre-odontocete basilosaurid archaeocetes. The hypothesis of the ‘toothed mysticete’ was invalidated here  in 2018.

“Recent phylogenetic analyses conducted across independent research efforts have
yielded a novel topology, wherein nonaetiocetid toothed “mysticetes” are recovered outside of Crown Cetacea, prior to the mysticete-odontocete split.”

See the LRT before more effort is put into this.

Source: https://pterosaurheresies.wordpress.com/2024/11/04/svp-abstracts-of-interest-or-bombast-2024-a-b/