SVP 2021 abstracts – 20: Origin of placental mammals

Carlisle et al. 2021 reports:
“Recent molecular clock analyses have suggested that placental mammals originated in the mid to late Cretaceous, before the Cretaceous–Paleogene (K–Pg) mass extinction.”

Don’t trust deep time gene studies. Too often they deliver false positives.

“However, there are no unequivocal fossils of placental mammals from the Cretaceous to
support this.”

The LRT recovered many unequivocal Cretaceous and Jurassic placentals (Fig. 1).
Add taxa to find your own.

Carlisle et al. continues:
“Definitive fossils of placental mammals only appear after the K–Pg boundary, at which point they rapidly radiate leading into the ‘Age of Mammals’.

Carlisle et al. should add taxa and discontinue promoting this myth.

“Here we use the Bayesian Brownian Bridge model to estimate the age of origin of placental mammals based on the fossil record.”

No need to estimate. Use the last common ancestor method.

“The model uses fossil diversity through time to inform a random walk from the clade’s present day diversity back to the estimated origin of the clade within a Bayesian framework. This model works well with clades that have poor fossil records, such as the early placental mammals, and does not require a phylogeny, thereby mitigating the lingering uncertainty over the branching pattern at the root of the placental tree of life.”

“Does not require a phylogeny?” These workers need to change their mind on this topic.

“Our results support a Cretaceous origin for placental mammals, in agreement with the molecular data, and demonstrate that the group was already present before the K–Pg mass
extinction and experienced a radiation during the Paleogene.”

The LRT origin of placentals is in the Jurassic… the Early Jurassic.

“The Bayesian Brownian Bride model can therefore help to reconcile paleontological data with
molecular data when estimating the origin of clades.”

No. The Carlisle et al. method was falsified by the LRT.

References
Carlisle E et al. 2021. The origin of placental mammals according to the fossil record. Journal of Vertebrate Paleontology abstracts.