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Fossils of amphibians and squamates are relatively common in Pliocene–Pleistocene sediments in the southeastern Atlantic coast of Buenos Aires Province (Argentina), particularly in the southern slope of the Tandilia mountain system. These taxa are less known in the northern slope, which in the county of Mar Chiquita are solely represented by one anuran record. Here, new herpetofaunal material is described from Mar Chiquita county in the northern slope of the Tandilia mountain system. These specimens, while few, present an interesting taxonomical and morphological diversity. From the Ensenadan outcrops, amphibians are represented by cf. Rhinella. On the other hand, Stenocercus, an indeterminate tropidurid, Colubroides, and an indeterminate snake account for the Ensenadan squamates. In the Bonaerian outcrops, squamates are represented by the viperid Bothrops and an indeterminate Pleurodont. These latter taxa are also present in the Lujanian with an indeterminate snake. These are the first fossil records of squamates from Mar Chiquita and together with the new and previous amphibian records constitute a herpetological assemblage (Ceratophrys ornata, cf. Rhinella, Stenocercus, and Bothrops) that suggests that the paleoclimatic conditions during the Pleistocene of the Pampean region would have been similar to those of the present day. This inference should be considered with caution, since it contradicts those suggested by the mammalian record, which is richer and presents taxonomic identifications that are more precise. Mammalian fossil records indicate a cold and dry glacial Pleistocene interspersed with short, warmer, and more humid periods.

En este trabajo se describen restos fósiles de teidos y anfisbenas recuperados de sedimentos pliocépliocénicos de la costa bonaerense, entre Mar del Plata y Miramar. Entre estos restos se incluyen especímenes previamente citados y otros pertenecientes a colecciones antiguas. Se documenta la presencia del género Tupinambis en el Chapadmalalense superior y el Marplatense (subpiso/subedad Vorohuense). La especie extinta, "T. onyxodon" Kraglievich 1947 es considerada inválida, mientras que citas de T. merianae son reevaluadas como de Tupinambis sp.. Restos de Amphisbaena sp. son identificados en el Chapadmalalense superior, representando el registro más temprano, hasta el momento, de un Amphisbaenia en América del Sur..Teiid and amphisbaenian reptiles from Pliocene beds along the coast of the Buenos Aires province, between Mar del Plata and Miramar, are described. They include previously listed remains as well as unreported material belonging to old collections. They document the presence of the teiid genus Tupinambis in Upper Chapadmalalan and Marplatan (Vorohuan) units. The extinct species "T. onyxodon" Kraglievich 1947 is considered invalid herein; also, previous cites of T. merianae are reevaluated as Tupinambis sp.. Remains of the amphisbaenid Amphisbaena sp. are identified in Upper Chapadmalal beds; they represent so far the earliest record of amphisbaenians in South America..

Resumen. Los escamosos conforman un exitoso grupo de reptiles que incluye más de 9.600 especies actuales. Su evolución en América del Sur, escasamente ilustrada por un registro fósil incompleto y episódico, es consecuencia de la compleja historia geológica y paleoclimática de esta parte del mundo. El registro del Mesozoico está concentrado principalmente en Argentina y Brasil, con menor presencia en Bolivia. Los principales clados de reptiles escamosos (Iguania y Scleroglossa) aparecen en el registro durante el Cretácico, donde las serpientes eran comunes y diversas, con algunas de las más primitivas formas terrestres. Los escamosos del Paleógeno y Neógeno provienen principalmente de Argentina, Bolivia, Brasil, Colombia, Perú y Venezuela. Los lagartos eran poco comunes en el Paleógeno pero las serpientes muestran una importante diversidad que incluye al menos dos boideos actuales (Boa y Corallus) y formas extintas. El Mioceno es especialmente relevante ya que se reconocen por primera vez algunos géneros actuales de Iguanidae (Liolaemus, Pristidactylus), Teiidae (Tupinambis) y otros Boidae (Eunectes, probablemente Epicrates), aunque también existen géneros extintos. La primera ocurrencia de Colubridae corresponde al Mioceno temprano, mientras que los Scolecophidia aparecen en el registro durante el Mioceno medio y los Viperidae en el Mioceno tardío. El más antiguo Amphisbaenia sudamericano es registrado en el Plioceno y los primeros Gekkonidae, Anguidae y Elapidae son del Pleistoceno. La mayoría de los escamosos del Pleistoceno y Holoceno corresponden a géneros actuales, incluyendo algunas especies vivientes. PALABRAS CLAVE. Lagartos. Anfisbenios. Serpientes. Mesozoico. Cenozoico. América del Sur. Abstract. ADVANCES IN THE KNOWLEDGE OF THE CONTINENTAL FOSSIL SQUAMATE REPTILES OF SOUTH AMERICA. The squamates are a successful group of reptiles which includes more than 9,600 extant species. Their evolution in South America, scarcely illustrated by the incomplete and episodic fossil record, is a consequence of the complex geological and paleoclimatic history of this part of the world. The Mesozoic squamate record is concentrated in Argentina and Brazil, with less presence in Bolivia. Both major squamate clades (Iguania and Scleroglossa) are present during the Cretaceous, where snakes were common and diverse, involving some of the most primitive terrestrial forms. Paleogene and Neogene squamates were mainly recorded in Argentina, Bolivia, Brazil, Colombia, Peru, and Venezuela. Lizards were uncommon in Paleogene deposits but snakes showed an important diversity which included at least two extant boid snakes (Boa and Corallus) and extinct forms. The Miocene is especially relevant because of the first recognition of some extant genera of Iguanidae (Liolaemus, Pristidactylus), Teiidae (Tupinambis), and other Boidae (Eunectes, probably Epicrates), although extinct genera were also present. First occurrence of Colubridae is from the early Miocene, whereas Scolecophidia appears in the middle Miocene, and Viperidae in the late Miocene. The earliest Amphisbaenia of South America is recorded in the Pliocene, and the earliest Gekkonidae, Anguidae and Elapidae come from the Pleistocene. Most Pleistocene and Holocene squamate remains correspond to living genera, including some extant species. KEY WORDS. Lizards. Amphisbaenians. Snakes. Mesozoic. Cenozoic. South America.