Thylacosmilus and Smilodon competition + Machairodus ecology + wing and fin beats

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Ben Creisler

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Jun 5, 2024, 3:06:29 PM (9 days ago) Jun 5
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Ben Creisler

Some recent non-dino papers:


Free pdf:

Jens Højgaard Jensen, Jeppe C. Dyre & Tina Hecksher (2024)
Universal wing- and fin-beat frequency scaling.
PLoS ONE 19(6): e0303834
doi: https://doi.org/10.1371/journal.pone.0303834
https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0303834


We derive an equation that applies for the wing-beat frequency of flying animals and to the fin-stroke frequency of diving animals like penguins and whales. The equation states that the wing/fin-beat frequency is proportional to the square root of the animal’s mass divided by the wing area. Data for birds, insects, bats, and even a robotic bird—supplemented by data for whales and penguins that must swim to stay submerged—show that the constant of proportionality is to a good approximation the same across all species; thus the equation is universal. The wing/fin-beat frequency equation is derived by dimensional analysis, which is a standard method of reasoning in physics. We finally demonstrate that a mathematically even simpler expression without the animal mass does not apply.

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Free pdf:

Roniel Freitas-Oliveira, Matheus S. Lima-Ribeiro & Levi Carina Terribile (2024)
No evidence for niche competition in the extinction of the South American saber-tooth species
npj Biodiversity 3: 11
doi: https://doi.org/10.1038/s44185-024-00045-7
https://www.nature.com/articles/s44185-024-00045-7


The end of South American isolation during the Great American Biotic Interchange (GABI) promoted the contact between South and North American saber-tooth forms that evolved in isolation. This contact may have driven saber-tooth species to a competitive interaction, resulting in the extinction of the South American saber-tooth form. Here, we used paleoclimatic data to compare the climatic niche of the saber-tooth forms Thylacosmilus atrox (from South America), Smilodon fatalis, and Smilodon populator (both originally from North America). We evaluated niche width, overlap, and similarity to infer potential geographic distribution overlap and competition between these North and South American predators. To do so, we obtained the climatic variables from sites where occurrence fossil records were available. Our results suggest that T. atrox had a narrower climatic niche compared to Smilodon species. Although we found a significant climatic niche overlap and similarity between S. fatalis and T. atrox, it seems unlikely that both species have co-occurred. Low niche overlap and similarity between T. atrox and S. populator dismiss competitive interaction between them. Moreover, climatic niche and low tolerance for environmental changes may have been the cause of the South American saber-tooth extinction.

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Free pdf:

Manuel J. Salesa, Bárbara Hernández, Pilar Marín, Gema Siliceo, Irene Martínez, Mauricio Antón, María Isabel García-Real, Juan Francisco Pastor & Rosa Ana García-Fernández (2024)
New insights on the ecology and behavior of Machairodus aphanistus (Carnivora, Felidae, Machairodontinae) through the paleopathological study of the fossil sample from the Late Miocene (Vallesian, MN 10) of Cerro de los Batallones (Torrejón de Velasco, Madrid, Spain)
Journal of Mammalian Evolution 31: 21
doi: https://doi.org/10.1007/s10914-024-09721-8
https://link.springer.com/article/10.1007/s10914-024-09721-8


The Late Miocene natural traps of Cerro de los Batallones (Madrid, Spain) have yielded thousands of fossils of vertebrates, mostly carnivoran mammals such as hyaenids, amphicyonids, ailurids, mustelids, ursids, and felids, especially Batallones-1 and Batallones-3. Among these carnivorans, the tiger-sized saber-toothed felid Machairodus aphanistus was the top predator of the association, and one of the most abundant taxa, represented by thousands of fossils, including several examples of bone pathologies that have never been studied. In this work, we carry out a paleopathological analysis of some of these pathologies from the Batallones sample of this large early machairodontine, with a description of the pathological changes that occurred in the affected bones, a possible diagnosis, and the ethological and ecological consequences of the presence of these diseases in the living animal. The pathological sample of M. aphanistus studied here included a calcaneus and a Mc III from Batallones-1, and a mandible from Batallones-3. The fossils were X-rayed, and their pathologies were described and compared to non-pathological bones. The calcaneus showed a bone callus indicative of osteitis/osteomyelitis or a tumor; the mandible had evidence of the development of an abscess located in the left mandibular body; and the Mc III shows a marked osteosclerosis. These injuries affected the hunting ability of these individuals and gradually weakened them, very likely contributing to their final entrapment in the Batallones cavities, where they were attracted by the presence of previously trapped animals.

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