SW hill of Vallecillo, Nuevo Leon (Cretaceous to of Mexico)

Where: Nuevo Leon, Mexico (26.7° N, 100.0° W: paleocoordinates 28.0° N, 69.0° W)

• coordinate estimated from map

• small collection-level geographic resolution

When: Upper Member (Agua Nueva Formation), Middle Turonian to Middle Turonian (93.5 - 89.3 Ma)

• We tentatively suggest that the sediments exposed on the hill west of the VPLM quarry field represent the Upper Agua Nueva Formation, which would then include middle and upper Turonian stages based on its stratigraphic position above the VPLM.

•However, there is no definitive evidence for a Late Turonian age for the mosasaur-bearing sediments, and the sequence exposed on the hill near Vallecillo may have easily reached

•into the Coniacian.

• bed-level stratigraphic resolution

Environment/lithology: platform or shelf-margin reef; massive, black, gray limestone and claystone

• The Agua Nueva Formation is widely distributed in the region and was deposited on a moderately deep, low-relief platform, along the western coast of the Gulf of Mexico and extending to the Western Interior Sea Way of the United States and the Gulf of Mexico Basin (Goldhammer and Johnson, 2001; Ifrim, 2006; Muir, 1936; Sohl et al., 1991).
• Although the precise location of the mosasaur is not known, the specimen was discovered in a small quarry of dark grey limestone. No lamination was identified in the sediment, which preserves no apparent internal structures.

Size class: macrofossils

• Skull (CPC 2972), missing the anterior rostrum and part of the right side.

Collected by Margarito Gonzalez

Collection methods: quarrying, surface (in situ), mechanical,

• MUDE- Museo del Desierto, Saltillo, Mexico.

•The material described here was collected by Margarito Gonzalez, who found the fossil in a quarry spoil heap. He informed the Museo del Desierto (MUDE) of his discovery and donated the specimen to the MUDE for scientific study and housing. The specimen was measured using digital calipers, and photographed using a Canon EOS Rebel T2i with a lens Canon 18–55 mm 1:3.5–5.6.6 ISII and a Nikon COOLPIX P610 with a lens Nikon standard (4.3–258 mm 1:3.3–6.5).

Primary reference: H. E. Rivera-Sylva, N. R. Longrich, J. M. Padilla-Gutierrez, J. R. Guzmán-Gutiérrez, V. M. Escalante-Hernández and J. G. González-. 2024. A new species of Yaguarasaurus (Mosasauridae: Plioplatecarpinae) from the Agua Nueva Formation (Upper Turonian – ?Lower Coniacian) of Nuevo Leon, Mexico. Journal of South American Earth Sciences 133(104694) [E. Vlachos/F. Aspromonte]more details

Purpose of describing collection: taxonomic analysis

PaleoDB collection 230590: authorized by Evangelos Vlachos, entered by Franco Aspromonte on 05.07.2023

Creative Commons license: CC BY (attribution)

Taxonomic list

Show authors, comments, and common names
Reptilia
 Squamata - Mosasauridae
Yaguarasaurus regiomontanus n. sp.
Yaguarasaurus regiomontanus n. sp. Rivera-Sylva et al. 2024 mosasaur
CPC 2972, partial skull