Document downloaded from: http://hdl.handle.net/10251/153787 This paper must be cited as: Company Rodríguez, J. (2017). Unusually thick dinosaur eggshell fragments from the Spanish Late Cretaceous. Historical Biology (Online). 31(2):203-210. https://doi.org/10.1080/08912963.2017.1357717 The final publication is available at https://doi.org/10.1080/08912963.2017.1357717 Copyright Taylor & Francis Additional Information Historical Biology For Peer Review Only Unusually thick dinosaur eggshell fragments from the Late Cretaceous of The Iberian Range, Spain. Journal: Historical Biology Manuscript ID Draft Manuscript Type: Original Article Date Submitted by the Author: n/a Complete List of Authors: Company, Julio; Universidad Politecnica de Valencia, Departamento de Ingeniería del Terreno dinosaur eggshells, Megaloolithidae, Megaloolithus aff. siruguei, Late Keywords: Cretaceous, Spain URL: http://mc.manuscriptcentral.com/ghbi Page 1 of 26 Historical Biology 1 2 3 1 Unusually thick dinosaur eggshell fragments from the Late 4 5 2 Cretaceous of Spain. 6 7 8 3 Julio Company 9 10 11 4 Departamento de Ingeniería del Terreno, Universidad Politécnica de Valencia, 46022 12 5 Valencia, Spain 13 14 6 For Peer Review Only 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 2 of 26 1 2 3 7 Unusually thick dinosaur eggshell fragments from the Late Cretaceous 4 5 8 of Spain. 6 7 8 9 Recent fieldwork carried out in the south-eastern branch of the Iberian Range 9 10 10 (Valencia province, Spain) has produced a large collection of dinosaur eggshell 11 11 fragments of unusual thickness. The specimens, up to 4.8 mm thick, were 12 13 12 recovered from palustrine grey marls of the upper Campanian-lower 14 13 MaastrichtianFor PeerSierra Perenchiza Review Formation, which constitutes Only the deposits of a 15 16 14 wetland paleoenvironment. The eggshell fragments exhibit a characteristic 17 15 compactit uberculate ornamentation, a tubospherulitic organization , and a 18 19 16 complex canaliculate respiratory system . The external tuberculate surface of the 20 17 shell and the internal microstructure permit to refer the studied specimens to 21 22 18 Megaloolithus aff. siruguei , the most common megaloolithid oospecies in the 23 24 19 Iberian Peninsula and Southern France. The biostratigraphic range of 25 20 Megaloolithus siruguei matches the temporal distribution of titanosaurid 26 27 21 dinosaurs in the Iberian Range, which are tentatively considered to be potential 28 22 producers. 29 30 31 23 Keywords: dinosaur eggshells, Megaloolithidae, Megaloolithus aff. siruguei , 32 24 Late Cretaceous, Spain. 33 34 35 25 36 37 38 39 26 Introduction 40 41 27 The Upper Cretaceous continental deposits of the Iberian Peninsula and Southern 42 43 28 France (Ibero-Armorican Island) have produced an extensive record of dinosaur 44 45 29 remains since the 19th century (Allain & Pereda-Suberbiola 2003; Csiki-Slava et al. 46 47 30 2015; Canudo et al. 2016). The most productive localities are principally concentrated 48 49 31 in the Pyrenean domain (Spain and France), Provence and Occitan (south-eastern 50 51 52 32 France), and the Iberian Range (eastern Spain). This record includes skeletal remains as 53 54 33 well as abundant oological and ichnological material. Up to eight different eggshell taxa 55 56 34 have been defined in the Ibero-Armorican domain (Vianey-Liaud et al. 2003), albeit 57 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 3 of 26 Historical Biology 1 2 3 35 nowadays not all them are considered valid oospecies (for a complete revision, see 4 5 36 Sellés, 2012; Fernández and Koshla, 2013). 6 7 37 Recent fieldwork carried out in the foothills of the Sierra de Malacara 8 9 10 38 (southwestern Iberian Range, Valencia province, Spain) has yielded abundant dinosaur 11 12 39 eggshell fragments of the megaloolithid type. The fragments, of unusual shell thickness, 13 14 40 greatly exceedsFor the usualPeer parameters Review described for the megaloolithid Only structural type 15 16 41 (Vianey-Liaud et al. 1994). The aim of the present work is to provide a detailed 17 18 42 description of the microstructure of the recovered specimens, to determine their 19 20 21 43 taxonomic position within the family Megaloolithidae, and to chronostratigraphically 22 23 44 test the main hypothesis about the identity of the producer dinosaur group. 24 25 26 27 45 Locality and stratigraphy 28 46 The material described herein was collected from pale grey-pink pedogenic marls 29 30 31 47 exposed in a 20-metres roadcut of deposits of the Late Cretaceous Sierra Perenchiza 32 33 48 Formation in the southern part of the Iberian Range (eastern Spain), next to the 34 35 49 Yegüeros creek, approximately 8 km west of the village of Buñol, Valencia province 36 37 50 (Figure 1). The Sierra Perenchiza Formation constitutes a late Campanian-early 38 39 40 51 Maastrichtian carbonate succession of interbedded palustrine marls and limestones with 41 42 52 strong evidence of pedogenic modification (Vilas et al. 1982; Alonso et al. 1991; Garcia 43 44 53 et al. 2004). These facies represent the sediments of seasonal wetlands, heavily 45 46 54 modified by vegetation and by subaerial exposure (Freytet & Plaziat 1982; Wright & 47 48 55 Platt 1995, Alonso-Zarza & Wright 2010). 49 50 51 56 Neighbouring outcrops of the Sierra Perenchiza Formation, located about 20 km 52 53 57 to the north, have yielded a rich vertebrate assemblage composed largely of dinosaurs, 54 55 58 crocodiles, pterosaurs, and aquatic chelonians. Microvertebrate remains have also been 56 57 59 recovered by screen-washing the sediments, including bony fish, squamates and 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Historical Biology Page 4 of 26 1 2 3 60 amphibians, together with tiny eggshell fragments, freshwater invertebrates (gastropods, 4 5 61 ostracodes, and bivalves), and charophyte remains (Company 2004; Company & 6 7 62 Szentesi 2012). 8 9 10 63 The paleoecological association and the sedimentological traits of these deposits 11 12 64 place the Sierra Perenchiza fossil localities in a palustrine paleoenvironment at the end 13 14 65 of the Cretaceous,For settledPeer in the western Review Tethyan margin of theOnly Iberian coastline. 15 16 17 18 66 Materials and methods 19 20 67 More than 100 eggshell fragments were recovered by surface prospecting in a single 21 22 68 collecting site of approximately 500 square meters. They range from small pieces of 23 24 69 few millimetres up to larger pieces of 3.5–4 cm in size. Even smaller fragments were 25 26 70 recovered by screen-washing a bulk sample of sediment (ca. 25 kg), which also 27 28 71 produced tiny fragments of crocodile eggshells, abundant charophyte remains, 29 30 31 72 ostracodes and fragmentary freshwater gastropods. Neither complete eggs nor dinosaur 32 33 73 skeletal remains were found in the locality. The specimens are relatively equally well- 34 35 74 preserved, without noticeable signs of abrasion, and display a similar external 36 37 75 appearance, so it is presumed that the fragments had not been subject to significant 38 39 40 76 transportation and come from the same nesting area. 41 42 77 Eggshell fragments were cleaned with 30 sec. ultrasonic baths. The process was 43 44 78 monitoring using a stereomicroscope. Shell thickness of each specimen was estimated 45 46 79 as the mean of three different measurements taken with a digital micrometer. Radial 47 48 80 thin sections of the specimens were prepared following standard petrographic methods. 49 50 51 81 The sections were studied under a petrographic microscope (Olympus BXTR BX40), in 52 53 82 both normal and polarized light. Images were captured with a mounted digital camera 54 55 83 (Sony Cybershot TM QX-100) and edited with Adobe© Photoshop CS5©. Surface 56 57 84 ornamentation and microstructural organization of smaller Au, Pd-coated fragments 58 59 60 URL: http://mc.manuscriptcentral.com/ghbi Page 5 of 26 Historical Biology 1 2 3 85 were examined using a scanning electron microscope (Philips XL30 ESEM FEG). 4 5 86 Nomenclature and definitions of eggshell microstructure used here are mainly based on 6 7 87 Mikhailov (1997). Specimens have been temporarily deposited in the collections of the 8 9 10 88 Polytechnic University of Valencia (Valencia, Spain). 11 12 13 89 Systematic palaeontology 14 For Peer Review Only 15 90 Oofamily Megaloolithidae Zhao, 1979 16 17 91 Oogenus Megaloolithus Vianey-Liaud, Mallan, 18 19 20 92 Buscail and Montgellard, 1994 21 22 93 Megaloolithus aff. siruguei Vianey-Liaud, Mallan, Buscail and 23 24 94 Montgelard, 1994 25 26 95 Figs. 2 & 3 27 28 96 29 30 31 97 Description 32 33 98 The eggshell fragments are composed of a single structural layer of calcite with a well 34 35 99 preserved surficial ornamentation (Figure 2). The eggshell thicknesses ranges from 1.8 36 37 100 to 4.8 mm, with an average of 3.45 mm (n = 125). The outer surface displays a distinct 38 39 101 compactituberculate ornamentation, consisting mostly of relatively rounded to 40 41 42 102 polygonal nodes which constitute the top of the shell units (Figures 2a-c). Occasionally, 43 44 103 neighbouring nodes coalesce, forming small chains. The average node diameter is about 45 46 104 0.59 mm, ranging from 0.34 to 0.90 mm in size. The pore openings are located in the 47 48 105 internodular spaces (Figures 2b-c).