Soft-Tissue, Rare Earth Element, and Molecular Analyses of Dreadnoughtus schrani, an Exceptionally Complete Titanosaur from Argentina

Abstract

Evidence that organic material preserves in deep time (>1 Ma) has been reported using a wide variety of analytical techniques. However, the comprehensive geochemical data that could aid in building robust hypotheses for how soft-tissues persist over millions of years are lacking from most paleomolecular reports. Here, we analyze the molecular preservation and taphonomic history of the Dreadnougtus schrani holotype (MPM-PV 1156) at both macroscopic and microscopic levels. We review the stratigraphy, depositional setting, and physical taphonomy of the D. schrani skeletal assemblage, and extensively characterize the preservation and taphonomic history of the humerus at a micro-scale via: (1) histological analysis (structural integrity) and X-ray diffraction (exogenous mineral content); (2) laser ablation-inductively coupled plasma mass spectrometry (analyses of rare earth element content throughout cortex); (3) demineralization and optical microscopy (soft-tissue microstructures); (4) in situ and in-solution immunological assays (presence of endogenous protein). Our data show the D. schrani holotype preserves soft-tissue microstructures and remnants of endogenous bone protein. Further, it was exposed to LREE-enriched groundwaters and weakly-oxidizing conditions after burial, but experienced negligible further chemical alteration after early-diagenetic fossilization. These findings support previous hypotheses that fossils that display low trace element uptake are favorable targets for paleomolecular analyses.

A importância das palavras-chave em Paleontologia Molecular: explorando o recurso Nuvem de Palavras para representação de tendências

“…An alternative to this problem is the use of the keyword exceptional preservation, which, in our opinion, better characterizes the high degree of preservation of details of histological, cellular, and molecular characteristics associated with endogenous and remaining original biomaterials that have been recovered from the fossil record (Alves & Machado, 2020). Research, Society andDevelopment, v. 11, n. 16, e06111637819, 2022 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v11i16.37819 Although it was not possible to identify it in our data, another important point of discussion is related to the fact that, in recent years, there has been a tendency to standardize the use of the term Molecular Paleontology as a keyword to be used in articles published by experts in the field (Cadena, 2016;Bailleul, et al, 2019;Ullmann, et al, 2019;Ullmann et al, 2021;Schroeter et al, 2022;Tahoun et al, 2022;Ullmann, et al, 2022). Therefore, we suggest that such a term, found in these more recent publications, be considered when choosing the keywords to be inserted in the manuscripts.…”

Celebrating dinosaurs: their behaviour, evolution, growth, and physiology

“…The search intensified with the report of the discovery of blood vessels in Tyrannosaurus rex (Schweitzer et al 2005(Schweitzer et al , 2007a. Broadly termed molecular palaeontology, these studies have been successful in showing that fossilization can include not only hard tissues like bone, but can also include osteocytes, layers of the skin, collagen fibres, muscle fibres, melanosomes, and other tissues that were not visible by unassisted optical observation (Schweitzer et al 2019; van der Reest and Currie 2020; Schroeter et al 2022;Tahoun et al 2022). If we ignore for the moment the feathered theropods of northeastern China (they will be discussed later), soft tissues (including in some cases possible genetic material) are now known for the theropods Citipati (Moyer et al 2016), Shuvuuia (Schweitzer et al 1999), and Tyrannosaurus rex (Schweitzer et al 2005), the sauropod Dreadnoughtus (Voegele et al 2022), the ankylosaur Borealopelta (Brown et al 2017), and the hadrosaur Brachylophosaurus (Schroeter et al 2017;Ullmann et al 2022).…”

Actualistic Testing of the Influence of Groundwater Chemistry on Degradation of Collagen I in Bone

“…Discovery of endogenous biomolecules in fossil bones, including DNA and proteins such as collagen I and osteocalcin, has become increasingly common over the last two decades (e.g., [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]) (Figure 1). These discoveries challenge long-held presumptions about the nature of fossilization and provide intriguing means of advancing several lines of current research, including: (1) identifying indeterminate fossil remains (e.g., [17,18]); (2) testing of phylogenetic hypotheses independent of skeletal morphology (e.g., [4,11,[19][20][21][22][23][24]);…”