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Evolution of Squamata Reptiles in Patagonia based on the fossil record

2011; Oxford University Press; Volume: 103; Issue: 2 Linguagem: Inglês

10.1111/j.1095-8312.2011.01691.x

1095-8312

Adriana M. Albino,

Scarabaeidae Beetle Taxonomy and Biogeography

The Squamata, a vertebrate group that includes ‘lizards’, amphisbaenians and snakes, have inhabited Patagonia since the Late Cretaceous. The Mesozoic record comprises an iguanian, a scleroglossan and a great diversity of snakes that include, among others, the most primitive terrestrial forms. Snakes were also well diversified in the Palaeogene, with fossils of madtsoiids and boids (including the oldest record of the extant Boa) found as far south as 46°S, following the then dominant subtropical conditions in the region. The Palaeogene record comprises small, medium-sized and large forms. The only boids that persisted at the beginning of the Neogene are all small forms, suggesting colder temperatures than during the Palaeogene. The oldest South American ‘colubrids’ made their first appearance at this time, reaching latitudes south of the current Patagonian distribution (50°S). The Neogene record also includes the first occurrence of extant iguanians (Pristidactylus and Liolaemus) and teiids (Tupinambis). The latter reached the southernmost distribution of its evolutionary history during the Miocene. The distribution of boids, ‘colubrids’ and tupinambine teiids at higher latitudes than at present indicates warmer conditions during the Miocene. The uplift of the Patagonian Andes, followed by a decrease in temperature and an increase in desertification, induced a strong contraction in the distribution of tupinambine teiids to northern regions of Patagonia and even forced the complete disappearance of boids from this region. In contrast, these changes appear to have favoured the diversification of iguanian genera on both sides of the Patagonian Andes. © 2011 The Linnean Society of London, Biological Journal of the Linnean Society, 2011, 103, 441–457. Los Squamata (‘lagartos’, anfisbenas y serpientes) habitan la Patagonia desde el Cretacico tardio. El registro Mesozoico comprende un iguanio, un esclerogloso, y una gran diversidad de serpientes que incluye las formas terrestres mas primitivas. Las serpientes estaban bien diversificadas durante el Paleogeno, con madtsoideos y boidos (incluyendo el registro mas antiguo de la actual Boa) que alcanzaron altas latitudes (46 °S) siguiendo las condiciones subtropicales dominantes en la region. En contraste con el Paleogeno, que incluye formas pequenas, medianas y grandes, los unicos boidos que persisten a comienzos del Neogeno son todas formas pequenas que sugieren temperaturas mas bajas que durante el Paleogeno. Los mas antiguos ‘colubridos’ sudamericanos son del Neogeno, cuando alcanzan latitudes (50 °S) al sur de su actual distribucion. El registro del Neogeno tambien incluye la aparicion de generos actuales de lagartos iguanios (Pristidactylus y Liolaemus) y teidos (Tupinambis). Tupinambis alcanza la distribucion mas austral durante el Mioceno. La presencia de boidos, ‘colubridos’ y teidos tupinambinos a mayores latitudes que en el presente indica condiciones mas calidas durante el Neogeno. El levantamiento de los Andes Patagonicos, seguido por la disminucion de la temperatura y el incremento de la aridez, produjo una fuerte contraccion en la distribucion de teidos tupinambinos hacia el norte y la desaparicion total de boidos de Patagonia. En contraste, estos cambios parecen haber favorecido la diversificacion de los generos de iguanios a ambos lados de los Andes.