Eschatornis, new phorusrhacid from Pleistocene of Brazil + sebecid tooth marks from Eocene of Brazil + Chicxulub mega-earthquake and seismic aftermaths

[Ben Creisler]

Ben Creisler

bcre...@gmail.com

Some recent Cenozoic-related papers:

Eschatornis aterradora gen. et sp. nov.

Victor Hugo M. Machado, Marcelo F. de Vasconcelos, Luciano Vilaboim Santos, Rodrigo Parisi Dutra, Cástor Cartelle, Bruno G. O. Câmara, Mário A. T. Dantas & Federico J. Degrange (2026)
A new terror bird (Cariamiformes, Phorusrhacidae) from the Late Pleistocene of Brazil: insights into the last representatives of the family
Papers in Palaeontology 12(2): e70080
doi: https://doi.org/10.1002/spp2.70080
https://onlinelibrary.wiley.com/doi/10.1002/spp2.70080

Terror birds comprise an iconic group of apex predator birds from America, with a rich fossil record that is one of the longest among birds for a Neoaves family, ranging from the middle Eocene to the latest Pleistocene. Here, we report the discovery of a new genus and species of Phorusrhacidae, based on an incomplete tibiotarsus recovered from an Upper Pleistocene (25 326–25 733 cal yr BP) cave deposit in Bahia, northeastern Brazil, and previously interpreted as a New World vulture. The preserved morphology exhibits unique diagnostic features that support the recognition of a new species belonging to the small-size phorusrhacids, the Psilopterinae, a clade that probably had poor flying abilities. In addition to the systematic assignment, we discuss aspects of its palaeoecology (isotopic habitat and body mass estimate), providing new insights into the diversity and evolutionary history of the last known terror birds.

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L.M. Carneiro, L.C. Andrade, M.R. Arêas & R.C. da Silva (2026)
New records of mesoeucrocodylian tooth marks from the Paleogene of South America, Brazil: paleoecological implications
Journal of South American Earth Sciences 106044
doi: https://doi.org/10.1016/j.jsames.2026.106044
https://www.sciencedirect.com/science/article/abs/pii/S0895981126000969


Sebecids represented apex predators of the Paleogene in South America. These animals were the only known Paleogene clade of vertebrates in South America to have ziphodont teeth, which are buccolingually compressed and serrated. Several studies have demonstrated that this type of tooth leaves singular traces on bones. Here, we present new records of tooth marks (Knethichnus parallelus, Linichnus serratus, and Machichnus bohemicus) identified on metatherian dentary from the early Eocene of Brazil (MCT-1 fissure, Itaboraí Basin). We attributed them to predatory, defleshing, and necrophagous behaviors of sebecids. Evidence suggests that sebecids prey on small mammals of similar size, likely occupying a trophic niche comparable to that of extant varanids.

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Hermann D. Bermúdez, Michelangelo Martini, Francisco J. Vega, Liliana Bolívar, Vivi Vajda, Francisco A. Vega-Sandoval, Daniela Bermúdez & Ying Cui (2026)
The Chicxulub mega-earthquake: Stratigraphic evidence from the Cretaceous-Paleogene boundary of Colombian Pacific and northeastern Mexico
Journal of South American Earth Sciences 176: 106058
https://doi.org/10.1016/j.jsames.2026.106058
https://www.sciencedirect.com/science/article/abs/pii/S0895981126001100

Highlights

Evidence of deformation triggered by the Chicxulub impact in Colombia and Mexico
Deformation affects pre-impact, impact-derived, and post-impact deposits
We identify a graded sequence of structures, coinciding with the three zones established for seismites
Chicxulub impact triggered mega-earthquakes (magnitude Mw> 8.5)
Deformed post-impact deposits suggest massive seismicity lasting for years

Abstract

The Chicxulub impact coincides with the Cretaceous-Paleogene (K-Pg) boundary and is considered the trigger of the last of the "Big Five" mass extinction events in Earth's history. Although geophysical models suggest that the impact released enough energy to produce massive earthquakes affecting vast areas, the evidence is insufficient, and their sedimentological signature is poorly known and illustrated. Here, we show stratigraphic evidence of seismically-induced deformation triggered by the Chicxulub impact in K/Pg sites from Colombia and Mexico, revealing deformation affecting pre-impact, impact-derived, and post-impact deposits. We identify a graded sequence of structures, coinciding with the three zones established for seismites. From top to bottom: 1) the Soupy Zone, characterized by intense ductile deformation. 2) the Rubble Zone, characterized by a mixture of brittle and ductile deformation, and 3) the Segmented Zone, controlled by brittle deformation. Our results indicate that the Chicxulub impact triggered mega-earthquakes (magnitude Mw> 8.5). Estimates derived from projections based on tectonically generated earthquakes suggest that the “Chicxulub mega-earthquake” may have reached a magnitude between Mw ∼9.4 and Mw ∼11.3. Seismically-induced deformation affecting the strata deposited after the Chicxulub impact (hosting the biotic recovery successions, including the interval dominated by fern spores at Gorgonilla), suggests massive seismicity lasting for years. The stratigraphic evidence allows us to better understand the complex geological record of the K/Pg boundary in the Americas and characterize one of the most powerful earthquakes of the Phanerozoic. This knowledge goes beyond Chicxulub and may also be applicable to other mega-earthquakes in the geological record.

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[Wade Thompson]

All of these new finds about small terror birds surviving into the late Pleistocene has me wondering. Have we ever found any fossils that possibly date after the extinction of the last known large terror bird, Titanis?

[Wade Thompson]

By fossils, I mean fossils of large terror birds. I forgot to put that in my first reply.

[Alberta Claw]

To my knowledge, all credible reports of Pleistocene phorusrhacids are of small-bodied forms like this one.

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