Des scientifiques de l’Université Maimonides à Buenos Aires ont découvert en Argentine la plus vieux fossile connu d’un tétard géant qui vivait il y a plus de 160 millions d’années soit 20 millions d’années plus tôt que le dernier tétard identifié.
Ils ont trouvé, imprimés sur une plaque de grès, des morceaux de son crane et de sa colonne vertébrale ainsi que des impressions de ses yeux et de ses nerfs
Mais la façon dont ces tétards pouvaient évoluer pour donner des grenouilles ou anoures n’est pas connue.
Référence
Article
Published: 30 October 2024
Nature
The oldest tadpole reveals evolutionary stability of the anuran life cycle
Mariana Chuliver, and others
Abstract
Anurans (anoures) are characterized by a biphasic life cycle, with an aquatic larval (tadpole) stage followed by an adult (frog) stage, both connected through the metamorphic period in which drastic morphological and physiological changes occur1. Extant tadpoles exhibit great morphological diversity and ecological relevance2, but their absence in the pre-Cretaceous fossil record (older than 145 million years) makes their origins and early evolution enigmatic. This contrasts with the postmetamorphic anuran fossil record that dates back to the Early Jurassic and with closely related species in the Late Triassic (around 217–213 million years ago (Ma))3. Here we report a late-stage tadpole of the stem-anuran Notobatrachus degiustoi from the Middle Jurassic of Patagonia (around 168–161 Ma). This finding has dual importance because it represents the oldest-known tadpole and, to our knowledge, the first stem-anuran larva. Its exquisite preservation, including soft tissues, shows features associated with the filter-feeding mechanism characteristic of extant tadpoles4,5. Notably, both N. degiustoi tadpole and adult reached a large size, demonstrating that tadpole gigantism occurred among stem-anurans. This new discovery reveals that a biphasic life cycle, with filter-feeding tadpoles inhabiting aquatic ephemeral environments, was already present in the early evolutionary history of stem-anurans and has remained stable for at least 161 million years
Europe Solidaire 