Phorusrhacid fossil from Miocene of Colombia + giant caimanines from Miocene
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Ben Creisler
Nov 4, 2024, 12:14:59 PM11/4/24
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Ben Creisler
Our knowledge of the fossil avifauna from the Middle Miocene La Venta locality in Colombia is limited almost entirely to aquatic birds. Phorusrhacidae, popularly known as ‘terror birds’, are a group of highly diversified cursorial birds that played the role of apex predators during most of the Cenozoic. Here we present the first record of a phorusrhacid from the La Venta locality. This terror bird can be assigned to the ‘Phorusrhacinae’, a subfamily for which the monophyly is under debate. The fragment of left distal tibiotarsus represents the most northern record of this group for South America and may correspond to the largest terror bird that ever existed. This suggests that terror birds might also have inhabited more tropical ecosystems, providing evidence that they were apex predators in tropical palaeocommunities. Additionally, our research contributes to an understanding of the biogeographical patterns of the Phorusrhacidae lineage dispersal into northern South America and subsequent colonization of North America.
Fossil of huge terror bird offers new information about wildlife in South America 12 million years ago
Highlights
The reconstructed ancestral body size of Caimaninae exhibited small sizes.
The correlation between size and temperature explains largest caimanines.
Changes in the ecosystem in the Miocene played a pivotal role in the diversity.
Climatic conditions and evolutionary processes underscore the history of the group.
Abstract
Extant caimanines include the six modern species of caimans, which occur predominantly in South and Central America and are mostly medium-sized crocodylians. Nevertheless, the fossil record of the group reveals a significantly higher diversity, with remarkable body size variation. In particular, the giants Purussaurus and Mourasuchus, from the Miocene western Amazonian region, are two of the most prominent representatives. Previous work has demonstrated a correlation between the body size of crocodylians and abiotic factors throughout the Cenozoic; however, this relationship is poorly understood, particularly within the Caimaninae lineage. Here, we explore evolutionary body size patterns within Caimaninae, investigating the potential influence of climatic factors. Using a phylogenetically-informed method, we estimated the body size of 33 caimanine specimens, coupled with climatic variables from a General Circulation Model to reconstruct deep-time patterns. Our results indicate that giant Miocene caimanines are restricted to warmer conditions, with significantly less seasonal temperature variation. This suggests that the unmatching climatic conditions of the Miocene western Amazonian region possibly allowed the emergence of unique palaeoecosystems, favouring the sustenance of these very large crocodylians.
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New Cenozoic papers:
Free to read:
Federico J. Degrange, Siobhan B. Cooke, Luis G. Ortiz-Pabon, Jonathan S. Pelegrin, Cesar A. Perdomo, Rodolfo Salas-Gismondi & Andrés Link (2024)
A gigantic new terror bird (Cariamiformes, Phorusrhacidae) from Middle Miocene tropical environments of La Venta in northern South America
Papers in Palaeontology 10(6): e1601
doi: https://doi.org/10.1002/spp2.1601
https://onlinelibrary.wiley.com/doi/abs/10.1002/spp2.1601
Federico J. Degrange, Siobhan B. Cooke, Luis G. Ortiz-Pabon, Jonathan S. Pelegrin, Cesar A. Perdomo, Rodolfo Salas-Gismondi & Andrés Link (2024)
A gigantic new terror bird (Cariamiformes, Phorusrhacidae) from Middle Miocene tropical environments of La Venta in northern South America
Papers in Palaeontology 10(6): e1601
doi: https://doi.org/10.1002/spp2.1601
https://onlinelibrary.wiley.com/doi/abs/10.1002/spp2.1601
Our knowledge of the fossil avifauna from the Middle Miocene La Venta locality in Colombia is limited almost entirely to aquatic birds. Phorusrhacidae, popularly known as ‘terror birds’, are a group of highly diversified cursorial birds that played the role of apex predators during most of the Cenozoic. Here we present the first record of a phorusrhacid from the La Venta locality. This terror bird can be assigned to the ‘Phorusrhacinae’, a subfamily for which the monophyly is under debate. The fragment of left distal tibiotarsus represents the most northern record of this group for South America and may correspond to the largest terror bird that ever existed. This suggests that terror birds might also have inhabited more tropical ecosystems, providing evidence that they were apex predators in tropical palaeocommunities. Additionally, our research contributes to an understanding of the biogeographical patterns of the Phorusrhacidae lineage dispersal into northern South America and subsequent colonization of North America.
***
News:
Fossil of huge terror bird offers new information about wildlife in South America 12 million years ago
===
Ana Laura S. Paiva, Pedro L. Godoy, Emma M. Dunne, Alexander Farnsworth, Paul J. Valdes, Daniel J. Lunt, Wilfried Klein, Max C. Langer & Annie S. Hsiou (2024)
The role of climate on the emergence of giant caimanines (Crocodylia, Alligatoroidea) from the Miocene western Amazonian region
Palaeogeography, Palaeoclimatology, Palaeoecology 112582
doi: https://doi.org/10.1016/j.palaeo.2024.112582
https://www.sciencedirect.com/science/article/abs/pii/S0031018224005716
The role of climate on the emergence of giant caimanines (Crocodylia, Alligatoroidea) from the Miocene western Amazonian region
Palaeogeography, Palaeoclimatology, Palaeoecology 112582
doi: https://doi.org/10.1016/j.palaeo.2024.112582
https://www.sciencedirect.com/science/article/abs/pii/S0031018224005716
Highlights
The reconstructed ancestral body size of Caimaninae exhibited small sizes.
The correlation between size and temperature explains largest caimanines.
Changes in the ecosystem in the Miocene played a pivotal role in the diversity.
Climatic conditions and evolutionary processes underscore the history of the group.
Abstract
Extant caimanines include the six modern species of caimans, which occur predominantly in South and Central America and are mostly medium-sized crocodylians. Nevertheless, the fossil record of the group reveals a significantly higher diversity, with remarkable body size variation. In particular, the giants Purussaurus and Mourasuchus, from the Miocene western Amazonian region, are two of the most prominent representatives. Previous work has demonstrated a correlation between the body size of crocodylians and abiotic factors throughout the Cenozoic; however, this relationship is poorly understood, particularly within the Caimaninae lineage. Here, we explore evolutionary body size patterns within Caimaninae, investigating the potential influence of climatic factors. Using a phylogenetically-informed method, we estimated the body size of 33 caimanine specimens, coupled with climatic variables from a General Circulation Model to reconstruct deep-time patterns. Our results indicate that giant Miocene caimanines are restricted to warmer conditions, with significantly less seasonal temperature variation. This suggests that the unmatching climatic conditions of the Miocene western Amazonian region possibly allowed the emergence of unique palaeoecosystems, favouring the sustenance of these very large crocodylians.
==
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