Strontium Isotope Stratigraphy and the thermophilic fossil fauna from the middle Miocene of the East Pisco Basin (Peru)

Extensive Diversity and Disparity of the Early Miocene Platanistoids (Cetacea, Odontoceti) in the Southeastern Pacific (Chilcatay Formation, Peru)

“…The rich sample of platanistoids from the Chilcatay Fm collected in the localities of Ullujaya and Zamaca represents a unique opportunity to reconstruct the ecological roles for a significant portion of a fossil cetacean community that lived in a well-defined and limited space and time. In fact, all platanistoids from the Chilcatay Fm are restricted to an 18-19 Ma time interval and, with the only exception of Macrosqualodelphis ukupachai, are precisely positioned along the well-described stratigraphical sequence of a sedimentary basin for which environmental conditions and vertical and horizontal variations are well known [20][21][22]89,90]. Moreover, the platanistoid specimens from Ulluyaja and Zamaca here examined represent a significant part of the entire cetacean assemblage recorded by us (more than 180 specimens of cetaceans, although a significant portion has been referred to Odontoceti indet.…”

Distribution and paleoenvironmental framework of middle Miocene marine vertebrates along the western side of the lower Ica Valley (East Pisco Basin, Peru)

“…In the surroundings of the Ocucaje village (Ica desert), integrated studies aimed at elucidating the spatial and stratigraphic distribution of the fossil vertebrates from the Pisco Formation have been recently performed at the localities of Cerro Colorado, Cerro Los Quesos, Cerro Queso Grande and Cerro Ballena Esperante et al, 2015), resulting in the construction of a rather comprehensive overview of the late Miocene vertebrate assemblages from the Pisco Lagerstätte (Di Celma et al, 2017). Conversely, the middle Miocene basal strata of the Pisco Formation and their fossil vertebrate content have been only cursorily investigated (Bosio, Malinverno, Collareta, et al, 2020;Di Celma et al, 2017), although the lower Pisco strata are thought to be home to important fossils such as the holotypes of the basal delphinidan Incacetus broggi (Colbert, 1944;de Muizon, 1988) and the earlybranching cetotheriid whale Tiucetus rosae .…”

A rhinopristiform sawfish (genus Pristis) from the middle Eocene (Lutetian) of southern Peru and its regional implications

“…Nowadays, sawfishes are absent from the coastal waters of southern Peru. However, in the East Pisco Basin, pristids are known as fossils from the Miocene strata of both the Chilcatay and the Pisco formations (BIANUCCI et al, 2016b(BIANUCCI et al, , 2018LANDINI et al, 2017aLANDINI et al, , 2017ba, 2019DI CELMA et al, 2018bBOSIO et al, 2020). Of all these Miocene occurrences, which consist of rostral spines only, those that can be confidently identified at the genus level are assigned to Anoxypristis (e.g., BIANUCCI et al, 2018;BOSIO et al, 2020).…”

“…However, in the East Pisco Basin, pristids are known as fossils from the Miocene strata of both the Chilcatay and the Pisco formations (BIANUCCI et al, 2016b(BIANUCCI et al, , 2018LANDINI et al, 2017aLANDINI et al, , 2017ba, 2019DI CELMA et al, 2018bBOSIO et al, 2020). Of all these Miocene occurrences, which consist of rostral spines only, those that can be confidently identified at the genus level are assigned to Anoxypristis (e.g., BIANUCCI et al, 2018;BOSIO et al, 2020). While extant Anoxypristis is confined to the Indo-western Pacific region, this genus had once a much wider distribution, largely overlapping that of Pristis, being indeed present in several Eocene to Pliocene sites of Africa, Asia, Europe, and North America (e.g., CAPPETTA, 2012, and references therein).…”

“…Recent research (CARRILLO-BRICEÑO et al, 2018;PARTAR-RIEU et al, 2018;VILLAFAÑA et al, 2019) has investigated the role of physiological, ecological, and life-history traits, as well as the influence of environmental and historical factors in controlling the diversity and distribution of Pacific South American chondrichthyans in Neogene and Quaternary times, but sawfishes have not been specifically addressed by these studies. Nonetheless, some answers could come from observing that another iconic tropical cartilaginous fish, the extinct snaggletooth shark Hemipristis serra AGASSIZ, 1843, is thought to have contracted its range northwards as cool conditions took hold along the coasts of southern Peru, during a middle or late Miocene phase of a stronger Humboldt Current (BOSIO et al, 2020). Similarly, the horn shark Heterodontus BLAINVILLE, 1816, seems to have been extirpated from most of its southeastern Pacific grounds following a series of regional changes, including seawater cooling due to coastal upwelling and advection of Subantarctic water masses, during the Plio-Pleistocene (PARTARRIEU et al, 2018).…”