CONTRIBUTI SCIENTIFICI Coprolite specimens from Pietraroja (lower Cretaceous, Southern Italy): morphological analysis by scanning electron microscopy G. Russo,1 P. Raia,2 M. Lauteri1 1Consiglio Nazionale delle Ricerche (CNR), Istituto di Biologia Agroambientale e Forestale (IBAF) - Porano (TR), Italy 2Università degli Studi Napoli Federico II, Dipartimento di Scienze della Terra, dell’Ambiente e delle Risorse, Naples, Italy Corresponding author: Giuseppe Russo Consiglio Nazionale delle Ricerche (CNR), Istituto di Biologia Agroambientale e Forestale (IBAF), Via Guglielmo Marconi 2, 05010 Porano (TR), Italy Tel. +39.0763.37491; Mobile: +39.320.5758929. E-mail: [email protected] only Summary The excavation in the palaeontological site of Pietraroja (Benevento, Italy) allowed to discover a large number of coprolites, though a precise stratigraphy would be only conceivable. The microscopic analysis of theuse samples provided valid elements to identify the producer and the palaoenvironment of the icno-fossilization, through the identifications of the inclusions and the possible causes of preservation. The final part of this study presents elements to identify the producer comparing the microscopical evidences of the coprolites with rests of associated fauna, in particular the plausible dental apparatus of a Notagogus pentlandi. Key words: coprolites, cretaceous, palaeoenvironment, fossils, fish, SEM. Introduction fossil traces. Though found in beyond 20 countries and from a wide temporal range (Palaeozoic- The Civita di Pietraroja (lat. 41.35; long. 15.55; Quaternary), often the coprolites without inclu- alt. 832 a.s.l.) is a locality on the commercialeastern Matese sions of bones were ignored in spite of the high mountains, 70 km northeast of Naples (Southern paleoecological information about the environ- Italy) (Figure 1). Since the 18th century, the area ment related to. Most of the literature is about cre- was known for the beautiful fossil fish, exquisitely taceous coprolites derived from dinosaurs, proba- preserved in marly limestone,Non that are called itti- bly herbivorous, as in the cases of India (Prasad et oliti (Italian, for fish-stones). The Civita di al., 2005) or the Two Medicine formation in Pietraroja locality is actually a fossil Lagerstätte, Montana, USA (Chin, 2007). In the European dated to the Lower Cretaceous. The area of the Cretaceous some cases evidenced small copro- main fossil site is loosely fenced, several buildings lites as in Portugal (Friis et al., 2004) or the ter- have been built on the fringes of the ’official‘ fossil mite coprolites in France (Colin, 2011). Fish site, including a football field and a never complet- coprolites from Morocco were studied (Lamboy et ed hospice for elder persons and two water reser- al., 1994) and, considering the paleogeography of voirs. All of these buildings were built upon layers Cretaceous, this represents the nearest scenario of fossiliferous limestone, thus hampering to Pietraroja site: a tropical lagoon with the contri- research and recovery of fossils (Signore, 2004). bution of a submarine channel (Carannante et al., The coprolites are icnofossils, members of a 2006). group of fossil traces that includes regurgitalites (dejections from the oral cavity) and colalites Materials and Methods (intestinal content fossilized in situ). Hunt (1992) utilized the term bromalites to include all these The specimens from the Pietraroja site are not 53 Marzo 2015 microscopie CONTRIBUTI SCIENTIFICI linked to a precise stratigraphy; unfortunately, the Corporate, Oregon, USA), at the CISME center of excavation of the site has presented many prob- the Federico II University of Naples. lems (Signore, 2004) and the coprolites are a sort of remains, both for technical and preconception reasons, in spite of the potential palaeo-informa- Results and Discussion tions that they can provide. It is more plausible that these fossils came from the more massive cat- The first question could be: are the samples astrophic layer, most possibly developed by rapid coprolites? In fact, the samples could be simple and catastrophic events of submarine slides sedimentary phosphates. The nature of coprolites (Signore, 2004) because the specimens including is suggested by their large quantities in a paleoen- coprolites were often associated with dental bat- vironment identified as water-based, the probable teries coming from durophagous fish, most possi- nature of inclusions (Figures 2-5) as vegetables bly Coelodus sp. (Signore, 2004). The specimens (the coprolites of herbivorous presents an elevat- analyzed, about 1-4 cm long, are several but the ed degree of conservation; Hill, 1976) and the only considered were those without macroscopic presence of phosphate: actually the causes of inclusions (bones, unidentified rests) and includ- phosphatization process are not known but the ing eventual microscopic details. Observations by coprolites represent the main site of enucleation Scanning Electron Microscope (SEM) were made for the precipitation ofonly the apatitic sediment (Ece, on specimens, previously metalized by a vacuum 1990). The external morphology of the observed evaporator JEE 4B (Jeol USA Inc.), and coated by coprolites does not permit to identify the fecal 10-20 mg of gold. Specimens were subsequently producer or to classify easily the icnofossil observed under a Quanta 200 ESEM (FEI according touse a discrimination about polarity. In commercial Non Figure 1. The Lagerstätte of Pietraroja (Italy). microscopie Marzo 2015 54 CONTRIBUTI SCIENTIFICI fact no kind of morphology or remark of lamina- cannot detect carbon and nitrogen. Moreover the tion is identifiable; then the analysis of inclusions association in the fossil record allows the copro- only can be predictive. In spite of these consider- lites to be related to the fish-fauna, because dental ations, the preservation of the fossil gives general apparatuses from durophagous and carnivorous information about the producer: the preferential fish were discovered in the same paleoenvirmo- preservation of the coprolites is the diet. Bradley nent. The group of the observed fibers (Figure 2a; (1946) suggested that calcium phosphate of the Figure 3; Figure 4) exhibiting a spiral pattern is carnivorous diet can be the best permineralizant consistent with materials digested and dejected by agent. Ca and Si are the most frequent elements in evolved fish groups (Kapoor et al., 1975), though the samples as recognized by the SEM probes, the inclusion would be considered as compressed. most likely these elements compose the grain and The pores, identified at higher magnification the matrix of the specimens; the same instrument (Figures 2b; 5 a-d), appear bended if compared only use Figure 2. Single vegetable fiber (a);commercial detail of a presumptive stomatal evidence (b). Bar: 50 μm (a); bar: 1 μm (b). Non Figure 3. High concentration of vegetable fibers. Figure 4. Single vegetable fiber present in the Bar: 500 μm. matrix of a coprolite. Bar: 100 μm. 55 Marzo 2015 microscopie CONTRIBUTI SCIENTIFICI with the length of the structure and in a serial suc- some higher plants adapted to xeric climate cession. This could implicate that the pores are (Schimper, 1903). The great quantity of preserved stomata, thus excluding that the inclusions might fishes in a lagoon of lower Cretaceous, the mor- be algae; furthermore algae were never found in phology of dejection and the absence of residual the fossil record of Pietraroja site. Initially, these bones suggest that the coprolite producer were vegetable fragments were supposed to belong to herbivorous fishes. the Gymnosperm group (which is present in the Another hypothesis deals with the entomologic Pietraroja paleoflora), but the traits observed nature of inclusions as tracheas of insect, dorsal would place the inclusions among the primitive vessels or crustacean esocuticle. The tracheas of Angiosperms, whose presence is not well docu- insects have a typical spiral structures (Strelin, mented in the fossil record though rests are cited 2012), but they do not resemble the observed in literature (Bartiromo et al., 2006). This could be inclusions, whereas the vessels which are made of consistent with the large diffusion of Angiosperms a soft tissue could hardly be fossilized or pre- since the lower Cretaceous at lower latitudes served; the inclusions found actually exhibit the (Hughes, 1994). The only doubtful feature is the rhomboidal forms as the scales of some crus- too small size of stomata (about 3 μm), though an taceans (Euphasiacea, Anfipodia) with pores epidermal accretion could make them less visible resembling stigma, but these crustacean taxa are and the typical sunken structure is similar as in absent in the fossil recordonly of Pietraroja. Thus, this use commercial Non Figure 5. Details of a vegetable fiber with stomatal evidence. Bar: 20 μm (a); bar: 4 μm (b-d). microscopie Marzo 2015 56 CONTRIBUTI SCIENTIFICI hypothesis is unlikely. Furthermore, studies on Elements to hypothesize Notagogus pentlan- the activity of fish digestive enzyme demonstrated di Agassiz as the coprolite producer that the chitinous material is completely degraded A remarkable case of association with the (Gutowska, 2002), while less than half of the plant coprolite samples is constituted by the discovery material ingested by an herbivorous fish is assimi- of a dental apparatus (Figure 6a-b); a similar struc- lated (Targett and Targett, 1990). The mechanisms ture was never found in the fossil record of of fossilization