Preservation of three-dimensional anatomy in phosphatized fossil arthropods enriches evolutionary inference

Abstract

External and internal morphological characters of extant and fossil organisms are crucial to establishing their systematic position, ecological role and evolutionary trends. The lack of internal characters and soft-tissue preservation in many arthropod fossils, however, impedes comprehensive phylogenetic analyses and species descriptions according to taxonomic standards for Recent organisms. We found well-preserved three-dimensional anatomy in mineralized arthropods from Paleogene fissure fillings and demonstrate the value of these fossils by utilizing digitally reconstructed anatomical structure of a hister beetle. The new anatomical data facilitate a refinement of the species diagnosis and allowed us to reject a previous hypothesis of close phylogenetic relationship to an extant congeneric species. Our findings suggest that mineralized fossils, even those of macroscopically poor preservation, constitute a rich but yet largely unexploited source of anatomical data for fossil arthropods.DOI: http://dx.doi.org/10.7554/eLife.12129.001

Deciphering the preservation of fossil insects: a case study from the Crato Member, Early Cretaceous of Brazil

“…For instance, the Cenozoic insect record includes: silicification (Palmer, 1957); phosphatisation and calcification (Leakey, 1952; Duncan & Briggs, 1996; Duncan, Briggs & Archer, 1998; McCobb et al, 1998; Grimaldi & Engel, 2005; Schwermann et al, 2016); and specimens preserved within gypsum crystals (Schlüter, Kohring & Gregor, 2002) Surprisingly, possibly silicified insects from Geiseltal (Eocene of Germany) have preserved respiratory system (tracheae), subcellular structures of muscles, digestive tract, reproductive organs, and glandular tissues (Voigt, 1938). …”

Peer Review #1 of "Exceptional soft tissues preservation in a mummified frog-eating Eocene salamander (v0.1)"

“…Permineralization of soft tissues by phosphorus leading to exceptional preservation was already observed in a few other cases, for embryophytes, arthropods and gastropods (Arena, 2008), ostracod sperm (Matzke-Karasz et al, 2014), and annelids (Wilson et al, 2016). Schwermann et al (2016a) also showed that air-dried specimens (as can be observed nowadays in lissamphibians after postmortem desiccation) do not accurately preserve soft tissues. This suggests that dead animals were rapidly buried in the sediment, a prerequisite for phosphatization of soft tissues (Wilson et al, 2016), where they were infiltrated by percolating water and thus permineralized.…”

“…In fossils, this tract is generally two-dimensionally preserved, with even sometimes its content (Dal Sasso & Signore, 1998;McNamara et al, 2010), or the tract content may be preserved without impression of the tract itself (e.g. Piñeiro et al, 2012), but never to our knowledge have a three-dimensional fossilized tract and its content been reported in vertebrates; however, threedimensional tracts, with perhaps remnants of the content, have recently been described in fossilized arthropods, which also come from the 'Phosphorites du Quercy' (Schwermann et al, 2016a). Phosphotriton may also be the only case of fossilization of an organ of the urogenital system (likely cloacal glands) among vertebrates (even though our interpretation of this structure is tentative) and it is the first known instance of an extinct salamander taxon and of a putative salamandrid (extinct or not) that fed on an adult anuran.…”

The NOVA project: maximizing beam time efficiency through synergistic analyses of SRμCT data

“…Thomas van de Kamp investigates the functional morphology of insects (particularly joint systems). He is interested in the application of X-ray imaging for entomology [30][31][32][33] and paleontology [34][35][36][37][38][39][40] as well as digital visualization and 3D reconstruction of biological samples [41][42][43] . The TU Darmstadt is responsible for the coordination of the project, but is also involved in data acquisition, and analysis.…”