A new Upper Cretaceous titanosaur nesting site from La Rioja (NW Argentina), with implications for titanosaur nesting strategies

Author(s)

Hechenleitner, E. Martin ^[1] ; Fiorelli, Lucas E. ^[1] ; Grellet-Tinner, Gerald ^{[1, 2]} ; Leuzinger, Lea ^[1] ; Basilici, Giorgio ^{[1, 3]} ; Taborda, Jeremias R. A. ^[4] ; De la Vega, Sergio R. ^[1] ; Bustamante, Carlos A. ^[1]

Affiliation

^[1] Ctr Reg Invest Cient & Transferencia Technol La R, Entre Rios & Mendoza S-N, RA-5301 Anillaco, La Rioja - Argentina

^[2] Orcas Isl Hist Museum, Eastsound, WA - USA

^[3] Univ Estadual Campinas, Inst Geociencias, Cidade Univ, BR-13083870 Campinas, SP - Brazil

^[4] Museo Argentino Ciencias Nat Bernardino Rivadavia, Secc Paleontol Vertebrados, Ave Angel Gallardo 470 C1405DJR, Buenos Aires, DF - Argentina

• Document type: Journal article
• Source: Palaeontology; v. 59, n. 3, p. 433-446, MAY 2016.
• Web of Science Citations: 4

Abstract

Cretaceous titanosaur nesting sites are currently known only from Europe, Asia and South America. In the latter, only the Auca Mahuevo and Sanagasta nesting sites have been confidently assigned to this clade of sauropod dinosaurs. Here we report the discovery of the first eggs and egg clutches found at Tama, a new Upper Cretaceous fossiliferous locality in the Los Llanos Formation, Sierra de Los Llanos (La Rioja, NW Argentina). At least five egg clutches, several partially preserved, isolated eggs and many eggshell fragments were discovered in a single outcrop of a sandstone horizon which represents a cumulative palaeosol profile. Although the mechanical and digital preparation of eggs did not reveal any embryonic remains in ovo, the morphology of the eggs and eggshells closely matches that of titanosaur eggs and eggshells found worldwide. The morphology and spatial grouping of the titanosaur eggs from Tama, along with geological observations support a burrow-nesting strategy for these dinosaurs. Although the Sanagasta and Tama eggs were found in the same stratigraphical unit and share several morphological characters, they clearly differ in shell thickness and egg size. This, coupled with the interpretation of different sedimentary contexts for these nesting sites, strongly suggests that at least two different titanosaur species nested in La Rioja during the Late Cretaceous, using different nesting strategies. The occurrence of this new titanosaur nesting site in a semiarid palaeoenvironment represents an interesting case study for the reproductive biology of the titanosaur dinosaurs, particularly their labile nesting behaviour. (AU)

• FAPESP's process: 12/23209-0 - Sediments and palaeosols of Cretaceous desert depositional systems (Bauru Group, SE of Brazil, and Los Llanos formation, W of Argentina): proxies for palaeoenvironmental interpretation and stratigraphic benefits
• Grantee: Giorgio Basilici
• Support Opportunities: Regular Research Grants