Journal of South American Earth Sciences 111 (2021) 103400 Available online 10 June 2021 0895-9811/© 2021 Elsevier Ltd. All rights reserved. Ammonites from the La Negra Facies (El Doctor Formation, late Albian) of the Muhi Quarry, Hidalgo, central Mexico Isabel L´ opez-Palomino a , Katia Adriana Gonz´ alez-Rodríguez b, * , Hans-Peter Schultze c , Arturo Palma-Ramírez d , Diana Contreras-Cruz e a L´ exico Estratigr´ afco de M´ exico, Ofcinas Centrales, Servicio Geol´ ogico Mexicano, Boulevard Felipe ´ Angeles Km. 93.50-4, Venta Prieta, Pachuca de Soto, Hidalgo, CP- 42083, Mexico b Instituto de Ciencias B´ asicas e Ingeniería, Museo de Paleontología, ´ Area Acad´ emica de Biología, Universidad Aut´ onoma del Estado de Hidalgo, Ciudad del Conocimiento, km 4.5 Carretera Pachuca-Tulancingo, 42184, Mineral de la Reforma, Hidalgo, Mexico c University of Kansas, Natural History Museum and Biodiversity Institute, Lawrence, KS, USA d Doctorado en Ciencias en Biodiversidad y Conservaci´ on, ´ Area Acad´ emica de Biología, Universidad Aut´ onoma del Estado de Hidalgo, Ciudad del Conocimiento, km 4.5 Carretera Pachuca-Tulancingo, 42184, Mineral de la Reforma, Hidalgo, Mexico e First Majestic Services, Universidad, no. 234, Lomas de Guadiana, C.P. 34110, Durango, Mexico A R T I C L E INFO Keywords: Mexico Ammonites late Albian Lower Cretaceous Biostratigraphic correlation Teleostean fshes ABSTRACT The fossil-rich limestones (La Negra Facies of the El Doctor Formation) in the Muhi Quarry, northwestern State of Hidalgo, Mexico are of late Albian age based on the occurrence of the ammonites Mortoniceras sp., Hamites aff. renzi and ?Beudanticeras sp. Their occurrence establishes the possible presence of the M. fallax, M. rostratum, M. prinfatum, and A. briacensis Zones (upper Albian) in North America. The late Albian age of the El Doctor For- mation makes its teleostean aulopiforms and acanthomorphs the oldest in the world and the occurrence of the chondrichthyans Ptychodus decurrens and Squalicorax falcatus, and the teleostean Tselfatiiformes are their oldest records in Mexico. 1. Introduction The Muhi Quarry is a Mexican fossil Lagerst¨ atte (Bravo-Cuevas et al., 2012) situated in northwestern Zimap´ an municipality of the State of Hidalgo that has been exploited for more than thirty years to obtain limestones for construction. The rocks of the locality contain a diverse Cretaceous marine biota, which includes nannoplankton, foraminifers, radiolarians (Ward, 1979; Bravo-Cuevas et al., 2009), ammonites, crustaceans (Vega et al., 2003; Feldman et al., 2007; Hegna et al., 2014), planktonic crinoids, echinoderm spines, fshes (chondrichthyans, acti- nopterygians and sarcopterygians) and indeterminate reptiles (Gonz´ alez-Rodríguez et al., 2013a, b, 2016; Fielitz and Gonz´ alez-Rodríguez, 2008, 2010; Gonz´ alez-Rodríguez and Fielitz, 2008, 2009; Arratia et al., 2018; Ba˜ nos-Rodríguez et al., 2020; Schultze and Gonz´ alez-Rodríguez, 2016). A preliminary report of the locality made by Gonz´ alez-Rodríguez and Bravo-Cuevas (2005) indicated that the Muhi Quarry was part of the San Joaquín Facies as established by Wilson et al. (1955), but a further study recognized that the site belongs to the La Negra Facies of the El Doctor Formation (Bravo-Cuevas et al., 2009). The El Doctor Formation was frst characterized in the northeastern State of Quer´ etaro (Carrasco, 1970, 1971, 1971; Wilson et al., 1955) and in the south-central State of Hidalgo (Fries, 1962; Segerstrom, 1961). The formation is 200–400 m-thick and consists of light gray micritic limestone intercalated by some chert nodules and marls. The rudists, Caprinulaidea gracilis and Mexicaprina sp., found in the rocks in north- eastern Quer´ etaro indicate an Albian-Cenomanian age for this unit (Ward, 1979). According to the aforementioned, and considering geographic position, this age has been assigned to the exposed rocks in the Muhi Quarry (Gonz´ alez-Rodríguez and Bravo-Cuevas, 2005; Brav- o-Cuevas et al., 2009). Vertebrates (mainly fshes) were reported for the frst time in the El Doctor Formation since the discovery of the Muhi Quarry (Gonz´ alez-Rodríguez and Bravo-Cuevas, 2005), increasing the fossil record in this Cretaceous unit. The ammonites in the quarry are scarce and poorly preserved, therefore their study has been diffcult. Previous interpretation of the specimens indicated the presence of Mortoniceras sp. (Esquivel-Macías, 2009), which was also verifed by G. Schweigert, Stuttgart, and J. Leh- mann, Bremen, indicating an Albian age (Gonz´ alez-Rodríguez et al., * Corresponding author. E-mail address: katiag@uaeh.edu.mx (K.A. Gonz´ alez-Rodríguez). Contents lists available at ScienceDirect Journal of South American Earth Sciences journal homepage: www.elsevier.com/locate/jsames https://doi.org/10.1016/j.jsames.2021.103400 Received 4 December 2020; Received in revised form 25 May 2021; Accepted 25 May 2021