Khosla, A. and Lucas, S.G., eds., 2016, Cretaceous Period: Biotic Diversity and Biogeography. New Mexico Museum of Natural History and Science Bulletin 71. 91 IMPORTANT CONTRIBUTIONS OF THE SOUTH AMERICAN RECORD TO THE UNDERSTANDING OF DINOSAUR REPRODUCTION

MARIELA SOLEDAD FERNÁNDEZ

Instituto de Investigaciones en Biodiversidad y Medioambiente, (INIBIOMA–CONICET), Quintral 1250, 8300, San Carlos de Bariloche, Río Negro, Argentina. e-mail: [email protected]

Abstract—South American fossil eggs display a very rich record in the Cretaceous, which permits an understanding of dinosaur reproduction. In this paper I review all dinosaur ootaxa described at the moment and discuss their relationships and geographical distribution. Macro characters of eggshells were studied and interpreted as a possible source of paleobiological knowledge, whereas several other macro characters are questioned or discussed. Three megaloolithid oospecies have been described for North Patagonia, and they have been compared with worldwide materials revealing the Gondwana distribution. Two fusioolithid eggshells were described, and one of them, Fusioolithis baghensis, was synonymized with Indian, French and Spanish materials, indicating that this widespread oospecies was laid by titanosaurs because they share the same features as the Auca Mahuevo eggs. Faveoloolithid eggs have been compared from La Rioja, La Pampa, Uruguay and Patagonia, reflecting that one kind of dinosaur was reproducing in all Argentina and Uruguay with this kind of eggshell. Theropod eggs have been described from Río Negro province, and ornithothoracean eggs have been compared from Neuquán city with those of Brazil, and apparently the same group was reproducing in both areas during the Late Cretaceous.

INTRODUCTION Formation, from Brazil (Price, 1951). These materials have been The amniotic egg was a great novelty in the evolution of related to the French sauropod Hypselosaurus. In fact, those dinosaur tetrapods. These complex structures allowed those animals to conquer eggs found in the Danian of the Provence region of France look similar new environments. Thus, its structure allowed them to reproduce in to them (Price, 1951). This Brazilian egg is spherical in shape, with a regions remote from bodies of water, so they were able to conquer 15 cm diameter, but the external surface has not been preserved, and diverse terrestrial environments (McFarland et al., 1979; Curtis and the egg just preserves its radial structural section. On the other hand, Barnes, 1993; Carpenter, 1999). The development of extra-embryonic the taxon Hypselosaurus (actually a nomen dubium) is not recorded in membranes gave to the embryo the aquatic environment for their correct Brazil, so because of that the egg was merely reassigned to the family development, so amniotic tetrapods could eliminate their larval stages, Titanosauridae, the sauropod family that includes Hypselosaurus so vulnerable to predation. The hard eggshells, composed of calcite (Price, 1951; Upchurch et al., 2004). or aragonite, provided to animals the protection from mechanical and The first fossil egg found in Argentina was collected from the physiological impediments, delimiting an isolated space with suitable basal part of the “rocanense” bed, a few kilometers from General conditions for the life of the embryo (McFarland et al., 1979; Curtis Roca city (Río Negro province). These fossils suffered a lithogenetic and Barnes, 1993). Dinosaurs, like most reptiles, reproduced by eggs, transformation, leaving only the external mold (Frengüelli, 1951). which are often preserved as fossils (Carroll, 1997; Chiappe et al., In Uruguay, dinosaur eggshells were collected from the Upper 2001; García, 2009). Cretaceous Ascencio Formation. Those materials were studied in detail South America dinosaurs have been successfully studied and by Erben in 1975, who determined that they belonged to at least two have a wide record from rocks of Cretaceous age. In this paper, I different taxa, cf. Ornithischia, family indet., genus Tacuaremborum and present a summary of all dinosaur egg taxa found in South America, Order Saurischia, cf. family Titanosauridae, genus Sphaerovum. Those more precisely in Argentina, and I will undertake a short discussion materials are silicified, so it is impossible to study their microstructure. of the reproductive biology of dinosaurs from the Late Cretaceous, Two genera and two species were identified from these eggshells, based on what we know so far. In South America, three megaloolithid Sphaerovum erbeni and Tacuaremborum oblongum (Mones, 1980). oospecies have been recorded to date (Megaloolithus jabalpurensis CHRONOLOGICAL CONTRIBUTIONS TO EACH OOFAMILY Khosla and Sahni, 1995, Megaloolithus cylindricus Khosla and Sahni, 1995, Megaloolithus megadermus Mohabey, 1998), two Fusioolithidae Megaloolithid eggs: Calvo et al. (1997) described the first oospecies (Fusioolithus baghensis (Khosla and Sahni, 1995) and oospecies from Neuquén, Megaloolithus patagonicus. In Neuquén Fusioolithus berthei Fernández and Khosla, 2015)), one faveoloolithid province, one of the most impressive nesting sites in the world, the oospecies (Paquiloolithus rionegrinus Simón 2002), one theropod Auca Mahuevo locality, was found. It encompasses hundreds of nests oospecies (Arriagadoolithus patagoniensis Kundrát, Novas, Agnolin in the Anacleto Formation, Campanian, Upper Cretaceous (Chiappe and Powell, 2012) and one enanthiornithine egg (referred to oofamily et al., 1998; Coria et al., 2007). In this locality the sedimentological Laevisioolithidae) are known. structure of six nests was studied. According to Chiappe et al. (2004), The oofamilies Megaloolithidae, Fusioolithidae and the dinosaurs used their fore limbs to dig their nests. Faveoloolithidae have been related to titanosaur sauropods (Chiappe Grellet-Tinner et al. (2007) described megaloolithid egg and et al., 1998; Grellet-Tinner et al., 2006; Salgado et al., 2007; Grellet- eggshells in Minas Gerais, Brazil (Baurú Basin, Upper Cretaceous). Tinner and Fiorelli, 2011; Fernández and Khosla, 2015). The oofamily These authors compared them with the Auca Mahuevo eggs, concluding Megaloolithidae has also been related to hadrosaurs (Grigorecu, 1994). that the Baurú eggshells are similar to those assigned to the Titanosauria. On the other hand, the only oospecies that have been described in Simón (1999) described eggshells of the Oofamily Megaloolithidae. Argentina and have been related to their producers are: Arriagadoolithus Salgado et al. (2007, 2009) published two articles describing two types patagoniensis to alvarezsaurid theropods, laevisioolithid eggs from of megaloolithid eggs that range in diameter between 10-12 cm. The Neuquén city have been related to ornithothoraces birds and Fusioolithus most important contribution of these works was that megaloolithid baghensis from Auca Mahuevo has been related with titanosaurs. On eggshells are associated with other kinds of eggshells in their nesting the other hand, in this report I will analyze the macrocharacters of the areas (Salgado et al., 2009; Coria et al., 2010). eggshells to interpret patterns of reproduction of these dinosaurs. The Coria et al. (2010) described two clutches from Bajo de Santa characters analyzed were: eggshell thickness, water vapor conductance, Rosa, where both clutches appear at the same level; the clutches are ornamentation and egg size. different in that they are integrated by eggs of different oofamilies: Megaloolithidae and Faveoloolithidae. Fernández and Khosla (2015) FIRST STUDIES IN SOUTH AMERICA described all of the megaloolithid materials from Salitral Ojo de Agua In 1951, a dinosaur egg was found in the Upper Cretaceous Baurú and Bajo de Santa Rosa, comparing them with the worldwide record. 92 These authors found that four of these oospecies are common in South pointed end downwards, a position that would have exposed the pole America, India, Africa and Europe. The oospecies in common are M. containing the air cell, and precluded egg turning, although there is no jabalpurensis, M. cylindricus, M. megadermus and F. baghensis. In evidence for nesting structures. This egg position is not seen in living addition, these authors described a new oospecies apparently endemic birds, with the exception of the basal galliform megapodes that place to South America, F. berthei. their eggs within mounds of vegetation or burrows (Garcia et al., 2008). Recently, a new oospecies, Pseudomegaloolithus atlasi This accumulation reveals a novel nesting behavior in Mesozoic Aves (Chassagne-Manoukian et al.. 2013) from Morocco was erected, that was perhaps shared with avian theropods and more basal troodontid and these authors have related megaloolithid materials from South theropods (Fernández et al., 2014). America to those from India (Chassagne-Manoukian et al., 2013). Otherwise, in 2014, the first avian fossil egg from Brazil were The fossil record of megaloolithids in Morocco indicates an ancient described, which were discovered in Upper Cretaceous deposits Gondwana ancestry for this group, and even is informative on the of the Vale do Rio do Peixe Formation in the Bauru Group of São relationship between these three areas during the Upper Cretaceous. Paulo in the southeastern part of the country. These eggshells of It indicates that megaloolithid producers, the titanosaur dinosaurs, 125.5-μm-thickness show three structural layers with both prismatic lived in Auca Mahuevo (Neuquén province), Bajo de Santa Rosa and aprismatic boundaries. This new Brazilian bird egg is similar to (Río Negro province), India, Bagh Cave (Madhya Pradesh), those of Enantiornithines from the Upper Cretaceous Bajo de la Carpa Balasinor, and in Europe, Coll de Nargó, Les Breguieres, and it Formation (Río Colorado Subgroup) of Argentina, which has been has been named F. baghensis. Jackson et al. (2013) described at the previously described and has affinity with basal Ornithothoraces-like Auca Mahuevo locality (Upper Cretaceous, Anacleto Formation) Argentinean materials. Furthermore, these authors indicated that for pedogenic processes associated with vertisol development that caused coherency of their depositional context it might imply a compatible changes in both individual titanosaur egg morphology and three- preference for breeding and nesting environments as in Patagonian dimensional egg distribution. These changes resulted primarily from Ornithothorace (Marsola et al., 2014). In the last decades several vertical and lateral movement within fluvial overbank sediments due studies were performed, and they will be reviewed in the parataxonomic to clay mineral expansion and contraction in alternating, wet-and-dry section. seasonal conditions. In their work, these authors concluded that these mechanisms of egg rearrangement suggest that accurate interpretation OTHER CONTRIBUTIONS OF DINOSAUR EGGSHELLS of dinosaur reproductive behavior using fossil egg assemblages Fernández and Matheos (2009) applied cathodoluminescence to preserved in fine-grained fluvial overbank deposits requires careful three kind of eggshell abnormalities. The first type consists of eggshells assessment of pedogenic processes. with altered microstructure and heterogeneous ornamentation, among Faveoloolithidae oospecies: Paquiloolithus rionegrinus Simón, which can be distinguished two conditions: eggshells without rosettes 2002 is distributed in Río Negro province (Allen Formation: Salitral (in megaloolithids and faveoloolithids), and eggshells with rosettes Ojo de Agua, Salitral Moreno, Salinas de Trapalcó, Bajo de Santa (in faveoloolithids); and the last one was multilayered eggshells Rosa, Yaminué) (Powell, 1992; Simón, 2002; Maghalaes-Ribeiro, (only in megaloolithids). Fernández (2013) studied 12 eggshells that 1997; Manera de Bianco et al., 2007; Salgado et al., 2007) and La were subjected to a Principal Component Analysis (PCA) to classify Rioja province (Sanagasta Locality). Tauber (1997) designated and establish the relationships between characters commonly used in eggshells as Faveoloolithidae, referring them to Sphaerovum erbeni parataxonomic classifications. Two main groups were identified: type 1, Mones 1980. Simón (2002) erected Paquiloolithus salitralensis, but eggshells related to the Oofamily Megaloolithidae, with five subtypes, without providing a complete description, as this oospecies was briefly and type 2, eggshells with no subtypes assigned. Relevant traits found described in an abstract of a congress. within the PCA study were: shell thickness, the width of the shell units, In Uruguay, several eggs from two different localities were the diameter of the nodules, and the diameter of the mammillae. described from the Upper Cretaceous of Soriano and Algorta. These eggs were assigned to the oospecies Sphaerovum erbeni Mones 1980, BRIEF DISCUSSION OF PARATAXONOMY OF and included in the Oofamily Faveoloolithidae (Faccio, 1994). Similar FOSSIL EGGS FROM SOUTH AMERICA materials were collected in La Pampa province, from the Colorado South America is one of the more rich areas with fossil eggshells, Formation (Campanian- Maastrichtian, Upper Cretaceous), assigned to eggs and nests. In South America, nine oospecies have been described. the oospecies Sphaerovum erbeni, and assigned, like Faccio (1994), to Here, I present a synonymy list for each dinosaur oofamily found in the Oofamily Faveoloolithidae (Casadío et al., 2002). Later, Grellet- South America: Tinner and Fiorelli (2011) designated Sphaerovum erbeni Mones 1980 as a nomen dubium. Soto et al. (2012) described materials from the Oofamily MEGALOOLITHIDAE Zhao, 1975 (emend. 1979) Guichón Formation, Late Cretaceous. These authors described material Megaloolithus jabalpurensis Khosla and Sahni, 1995: 90–91 that were assigned to Faveoloolithidae and Sphaerovum, and these Megaloolithus matleyi (Mohabey, 1996: 188–191) authors ignored the designation of nomen dubium given by Grellet- Megaloolithus patagonicus (Calvo, Engelland, Heredia and Salgado, Tinner and Fiorelli (2010). 1997: 27–30) Oofamily Arriagadoolithidae: In 2007, Salgado et al. studied some eggshells that have been described as Elongatoolithidae, Tipo 1b Fernández, 2013 describing two layers in the histo-structure of the Salitral Ojo de Remarks: Megaloolithus jabalpurensis is the senior synonym of Agua eggshells. Five years later, Agnolin et al. (2012) described two the South American oospecies described as Megaloolithus patagonicus incomplete eggs associated with skeletal remains of the alvarezsaurid described by Calvo et al. (2007) for eggs from Neuquén city. In a previous Bonapartenykus; several clusters of broken eggshells of the same study Fernández and Khosla (2015) synonymized M. jabalpurensis with identity were found in close proximity to the eggs. These authors named several materials from India and South America (please see Table 1 for the eggs as Arriagadoolithus patagoniensis and provided a complete their macrocharacter features and see Fernández and Khosla (2015) for description of eggs and eggshell structure. Unlike Salgado et al. (2007), a complete description). Stratigraphic distribution is described in Table these authors described a three layered eggshell. These eggs have been 8. The localities, age, formation and paleoenvironments are explained related to adult bones, as I mentioned above, though no hatchlings or in Tables 9 and 10. embryos have been found related to these materials. Oofamily Laevisoolithidae: In 2002, Schweitzer et al. described Megaloolithus cylindricus Khosla and Sahni, 1995: 89–90 for the very first time avian eggs with their death embryo inside of Megaloolithus rahioliensis (Mohabey, 1998: 349) them, which means a perfect preservation of fossil remains. These “Tipo 1 d” by Fernández 2013 authors studied the micro and ultrastructure of these eggshells and related them to ornithothoracean birds. In 2014, the first evidence of a Remarks: Megaloolithus cylindricus described by Khosla and nesting colony of Mesozoic birds on Gondwana, a fossil accumulation Sahni (1995) has been synonymized with M. rahioliensis Mohabey in Late Cretaceous rocks from The University of El Comahue Campus, (1998), as have materials named Tipo 1 “d,” described for Bajo de was reported. All eggs were found apparently in, or close to, their Santa Rosa, Río Negro province by Fernández (2013). These are a very original nest site; they all occur within the same bedding plane and interesting find because they were described as a new oospecies for may represent the product of a single nesting season or a short series of Argentinean materials that have since been related to Indian materials. nesting attempts. For a detailed comparison please see Fernández and Khosla (2015) and The Comahue eggs were half-buried upright in the sand with their Table 2. Stratigraphic distribution is described in Table 8. The localities, 93 age, formation and paleoenvironments are explained in Tables 9 and 10. Fiorelli (2011) Megaloolithus megadermus Mohabey, 1998: 353–357 Description: These South American materials have a Hypselosaurus (Kerourio, 1987: 257) (see Mohabey 1998) filispherulitic morphotype (Mikhailov, 1991), with a multicanaliculated (Type locality. Dansle Basin, France) pore system, external surface with conspicuous nodes by the end of “Tipo 1 e” by Fernández, 2013 each spherulite forms the external ornamentation. The external surface shows compactituberculate ornamentation. Spherical eggs that range Remarks: Megaloolithus megadermus was first described from between 18 to 22 cm in diameter. These eggs have eggshell thickness India (Mohabey, 1998). However, in 2015 Fernández and Khosla between 3.5 to 7.5 mm; average thickness 5.21 mm. The width of the synonymized materials from Argentina named as Tipo 1 “e” (Fernández, shell units range between 0.3 to 1 mm; the average is 0.54 mm. The 2013) that correspond with this previous oospecies described from diameter of the nodules ranges from 0.3 to 1.1 mm; the average is 0.59 India. This article documented the presence of this oospecies in mm. For the character “diameter of mamilla” it varies between 0.2 to Argentina. For more detailed description see Fernández and Khosla 1.1 mm, average is 0.54 mm. Under PLM fan-shaped extinction pattern (2015) and Table 3. Stratigraphic distribution is described in Table 8. is evident. The shell units grow from the inner part of the eggshell and The localities, age, formation and paleoenvironments are explained in each spherulite form long prisms some of which abort their growth, Tables 9 and 10. and just a few of them get to the external surface. During their growth, OOFAMILY FUSIOOLITHIDAE Fernández and Khosla 2015 the crystals start touching each other, forming an irregular net wall, where these spherulites surround the pore-canals (multicanaliculate Fusioolithus baghensis (Khosla and Sahni, 1995) pore-system). Under SEM subcircular nodes were observed. Between Megaloolithus baghensis (Khosla and Sahni, 1995: 91–92) each node the opening of pore-canals appears on the surface. The pore Megaloolithus pseudomamillare (Vianey-Liaud, Hirsch, Sahni and opening has an oval shape with a diameter of 4µm. In radial view we Sigé, 1997: 78–81) could observe that the shell units grow up branching and pore canals Megaloolithus balasinorensis (Mohabey, 1998: 357–358) open in an irregular manner. Patagoolithus salitralensis (Simón, 2006: 517, 521–523) Remarks: This kind of eggshells represents the most widespread Megaloolithus cf. baghensis (Sellés, Bravo, Delclós, and rich register from Argentina and Uruguay. During the last four Colombo, Martí, Ortega-Blanco, Parellada and Galobart, 2013) decades materials from Río Negro, La Rioja, La Pampa, Entre Ríos and Tipo 1 “a” Fernández 2013 Uruguay have been described. After a revision of all available literature on filispherulitic eggshells, it can be concluded that just one single type Remarks: The oospecies Megaloolithus baghensis is one of the of eggshell appears in Argentina and Uruguay related to titanosaurian most widespread oospecies. These eggs and eggshells represent the dinosaurs, referred to only one oospecies named Paquiloolithus first confident relationship between several eggs with their producer. rionegrinus Simón 2002, which still needs a complete formal In a previous work, Fernández and Khosla (2015) discussed the description for its proper assignment to parataxonomic systematics. affiliation of this oospecies to the oofamily Megaloolithidae, creating For a more detailed description please see Table 6. Stratigraphic a new oofamily Fusioolithidae, more accurate for these eggs without distribution is described in Table 8. The localities, age, formation and sharp shell units, as the diagnosis of Megaloolithidae considered. This paleoenvironments are explained in Tables 9 and 10. oospecies has been related to the Auca Mahuevo eggs, those which have been related to their producer, a titanosaur. These materials OOFAMILY ARRIAGADOOLITHIDAE Kundrát, Novas, have been described for the first time in Auca Mehuevo without an Agnolin and Powell 2012 accurate review of the eggshell designation, then other eggshells were Arriagadoolithus Kundrát, Novas, Agnolin and Powell (2012) described from Salitral Moreno by Simón (1996) and finally were described as Tipo 1 “a” by Fernández (2013) from Río Negro, Bajos Arriagadoolithus patagoniensis Kundrát, Novas, Agnolin and Powell de Santa Rosa and Salitral Ojo de Agua. Megaloolithus baghensis, in a (2012) subsequent step, was reassigned to the oofamily Fusioolithidae based Type 3 Oofamily Elongatoolithidae (Salgado et al., 2007) on microstructural character. The most relevant input of this paper was Remarks: The first descriptions of these materials were made to relate the eggs described in Auca Mahuevo with materials worldwide by Salgado et al. (2007). These authors described these eggshells with the same microstructural features of its eggshells. Bravo and Gaete superficially and found a two layered eggshell, without any remains of (2015) considered that Fernández (2013) established, mainly on the a complete egg. These authors related the materials with the oofamily basis of quantitative characters, that the eggshells found at the Auca Elongatoolithidae. In a subsequent work, Agnolin et al. (2012) studied a Mahuevo site were similar to the oospecies Patagoolithus salitralensis partial egg and eggshells from Salitral Ojo de Agua, Río Negro province (Simón 2006), but a complete description was provided in Fernández and they found that these materials preserved three layered eggshells, and Khosla (2015). and a very conspicuous ornamentation, which permitted them to erect The titanosaur eggs apparently are found in Europe, India and a new oofamily and a new oospecies. For a more detailed description South America. For a more detailed description please see Fernández please see Table 7. Stratigraphic distribution is described in Table 8. and Khosla (2015) and Table 4. Stratigraphic distribution is described The localities, age, formation and paleoenvironments are explained in in Table 8. The localities, age, formation and paleoenvironments are Tables 9 and 10. explained in Tables 9 and 10. OOFAMILY Laevisioolithidae Schweitzer et al. 2002 OOFAMILY FUSIOOLITHIDAE Fernández and Khosla 2015 Ornithothoracean Schweitzer et al. (2002) Fusioolithus berthei Fernández and Khosla (2015) Remarks: The first studies were performed at the Campus of Remarks: These eggshells represent the first record of a new Universidad Nacional del Comahue. Several eggs with embryos inside oospecies described for South America, and it represents an endemic the eggs were found. The features of the bones of these embryos kind of eggshell described from Río Negro province. Fusioolithus display some synapomorphies of ornithothoracean birds, and its berthei corresponds to Tipo 1 “c” described in Fernández (2013). F. eggshells present a three layered egg. These authors consider that these berthei is somewhat similar to M. jabalpurensis in having fan-shaped eggs belong to the oofamily Laevisioolithidae. In a subsquent study spheroliths of variable width and shape and subcircular nodes having Fernández et al. (2014) presented the first evidence for a nesting colony a common average nodal diameter (0.67 mm) but differs in eggshell of Mesozoic birds on Gondwana. These eggs were laid either singly, thickness. For a more detailed description please see Fernández and or occasionally in pairs, onto a sandy substrate. All eggs were found Khosla (2015) and Table 5. Stratigraphic distribution is described in apparently in, or close to, their original nest site. Eggs were half-buried Table 8. The localities, age, formation and paleoenvironments are upright in the sand with their pointed end downwards, a position that explained in Tables 9 and 10. would have exposed the pole containing the air cell and precluded egg turning. OOFAMILY FAVEOLOOLITHIDAE Zhao y Ding, 1976 Marsola et al. (2014) report the first fossil avian egg from Brazil, Paquiloolithus rionegrinus Simón, 2002 from Upper Cretaceous strata of São Paulo. These eggs show eggshell thickness of 125.5 μm; eggshells display three structural layers of Spherovum erbeni Mones 1980 similar thickness with both prismatic and aprismatic boundaries. Close Sphaerovum erbeni Mones 1980 as a nomen dubium Grellet-Tinner and similarity between the Brazilian bird egg and those of Enantiornithines 94 from the Upper Cretaceous Bajo de la Carpa Formation (Río zone there are no pores observed. As the eggs progress through the Colorado Subgroup) of Argentina indicate both have affinity with incubation process, and the embryos develop, the eggshells become basal Ornithothoraces. For a more detailed description see Table 7. more porous toward the poles, while in the equator zone the number of Stratigraphic distribution is described in Table 8. The localities, age, pores continue growing in number, and the existing pores increase in formation and paleoenvironments are explained in Tables 9 and 10. size (diameter). At the moment when the embryo ends its development, the entire eggshell is porous (Simoncini et al., 2014). The ontogenetic BIOLOGICAL INTERPRETATION OF EGGSHELL variation of the eggshell porosity has several benefits to the embryo: MACRO-CHARACTERS on the one hand, it increases the gas exchange as the embryo develops; Variability in Ornamentation of Faveoloolithid and on the other hand, the increased rate of porosity causes the eggshell Megaloolithid Eggs to become brittle, allowing the embryo to hatch (Ferguson, 1985). As in alligators and in penguins, old females have more porous eggshells The megaloolithid and faveoloolithid eggs recorded in the Salitral (Massaro and Davis, 2004). de Santa Rosa-Salinas de Trapalcó and Salitral Ojo de Agua localities show a great variability of nodule size. The diameter of nodules ranges EGGSHELL THICKNESS between 0.32 and 1.7 mm. Several authors (Cousin and Breton, 2000, By looking at the high variability of this character in faveoloolithid cited in Grellet-Tinner, 2006), claimed that the surface nodules of and megaloolithid eggs, several questions arise about the real meaning megaloolithid eggshells (in this case from France) provide information of the variation in shell thickness: does this character have taxonomic on the nature of the substrate or material in which the nest was built; value?; or, is it simply a response to ontogenetic variation in a taxon? indeed, these egg nodules could be interpreted as an adaptation to To answer this question I can mention an important case of thickness facilitate the conductance of gases and water vapor through the pores variation within a group of penguins. In these birds different variables (Grellet-Tinner et al., 2004, 2006). A similar interpretation could be related to the eggshells of different ages of females were studied. applied to the case of faveoloolithid and megaloolithid eggs from Variations indicate that older females laid eggs with greater shell Río Negro. These eggs were probably buried for incubation. In a thicknesses (Massaro and Davis, 2004). In this sense, at least part of the recent paper published by Hechenleitner et al. (2015) they observed observed variability in the Río Negro localities, shell thickness can be that the Sanagasta dinosaurs incubated their eggs with environmental the result of differences in female ages and size. sources of heat in burial conditions (Grellet-Tinner and Fiorelli, 2011). To reach that assumption they studied the clutch composition and DISCUSSION geometry, the nature and properties of the sediments, the structure of In South America five oospecies have been described distributed the eggshell and water vapor conductance. With all this information in Minas Geraíz Baurú (Brazil), Perú, Río Negro and Neuquén they said that it would appear that titanosaurs adopted nesting behaviors (Argentina). The most controversial oospecies are based on those comparable to the modern Australasian megapodes, using burrow- materials related to the Auca Mahuevo eggs, those which have been nesting in diverse media and mound-building strategies. related with titanosaur embryos. In a recent article Bravo and Gaete Density and Pore System in Sauropod Eggs (2015) explained that as other authors have followed the interpretation presented by Fernández and Khosla (2015), these authors ignored As has been widely reported, megaloolithid eggs have a previous studied performed by Salgado et al. (2007, 2009) that present tubocanaliculated pore system. Some authors have explained that the results that two kind of eggshells have been recorded for Río Negro size, shape, geometry and number of pore canals reflect the particular province. Simón described in 2006 a new oospecies for Salitral Moreno environment where eggs were incubated (see Grellet-Tinner, 2006). materials, Patagoolithus salitralensis. This author considered that Río Indeed, as is known from current studies on extant organisms, Negro materials are different from those described by Calvo et al. all traits linked to pores have a direct relationship with eggshell (2007) as M. patagonicus. conductance, namely, G = M / ΔP where G is water vapor H2O H2O H2O H2O In a further study, Fernández (2013) described five different conductance (mg*day-1*torr-1); M = weight loss rate (mg*day-1) and H2O types of megaloolithid eggs, and in a subsequent study Fernández and ΔP =differential pressure through the eggshell (torr) according to Ar H2O Khosla (2015) made a deep comparison of South American materials et al. (1974) (Deeming, 2006; Jackson et al., 2008). Thus, for example, with worldwide eggshells. In this report these authors realized that for a given equal shell thickness, a higher density of pore results in Patagoolithus salitralensis represents the same oospecies described higher conductance. from Auca Mahuevo and wrongly assigned to M. patagonicus by Conductance of water vapor for several species of Megaloolithus Grellet-Tinner et al. (2004). Fernández and Khosla (2015) based their was calculated, and a surprising variability was found in the same interpretations on ultrastructure, microstructure and macrostructural oogenus: in Megaloolithus patagonicus, conductance is 341 mg H O 2 features to erect a new oofamily and oogenus. Bravo and Gaete day (-1) Torr (-1), and in Megaloolithus siruguei it is 3979 mg H 0 day 2 indicated that Fusioolithus baghensis had been erected just with one (-1) Torr (-1) (Jackson et al., 2008). The relatively high conductance character, and that is incorrect. I recommend to these authors study of registered in the French oospecies compared with the Patagonian one the original materials, including thin sections of the specimens from indicates that the microenvironment of incubation was much more Río Negro and Auca Mahuevo, Neuquén that indicate that these two humid, possibly being achieved by covering the nest with sheets and/ oospecies represent one kind of eggshell in opposition to the results or sediment. of Salgado et al. (2007, 2009), Simón (2006), Fernández (2013) and Seymour (1979) studied bird eggshell conductance and then made Fernández and Khosla (2015). inferences about fossil materials. The birds generally incubate their Bravo and Gaete (2015) argued that “besides, other causes such eggs in an open nest; while reptiles incubate their eggs buried or laid as diagenetic processes (e.g., recrystallisation) may also play a role in their eggs in a mound of vegetation. However, as stated above, reptile the fusion of adjacent units” without any citation for this affirmation. A have eggs with thicker eggshells and higher water vapor conductance very complete article on cathodoluminescense presented by Fernández than do birds (Seymour, 1979; Jackson et al., 2008). It has been claimed and Matheus (2011) explains how recrystallization occurs and how that most of the dinosaurs buried their eggs or incubated their nests in it can be documented. These materials have been studied under vegetable materials, due to the high porosity (and high conductance) of cathodoluminiscence, and there are no clues that the shell units have their eggshells (Seymour, 1979; Sabath, 1991; Grigorescu et al., 1994; been recrystallized, as these authors explain (Fernández and Matheus, Deeming, 2002, 2006; Hechenleitner et al., 2015 ). 2011). These authors studied megaloolithid eggshells with cladistics. Jackson et al. (2008) observed that both megaloolithid oospecies In the tree presented by these authors I observed that the oospecies (Megaloolithus patagonicus and Megaloolithus siruguei) have higher from Auca Mahuevo appeared separate from the other megaloolithid water vapor conductance values than do birds. Of the two, the high eggs, supporting the idea presented by Fernández and Khosla (2015) rate of water vapor conductance of M. siruguei suggested to those that these eggshells represent a different taxon. authors that the eggs were covered with vegetable materials, unlike Hechenleitner et al. (2016) described five egg clutches, several those of Megaloolithus from Auca Mahuevo, which, on the basis of partial eggs preserved and many eggshells in Tama from the Upper their low conductance, had been uncovered during their incubation. Cretaceous Los Llanos Formation from Sierra de los Llanos. These However, there is evidence in extant reptiles that indicates that the pore authors consider them as titanosaur eggs based on the nodular density is not constant throughout (Simoncini et al., 2014). Indeed, in ornamentation of the outer shell surfaces and the complex pore Caiman latirostris Daudin, 1802, during the first stage of ontogenetic canal system that related their materials to the Auca Mahuevo eggs development, eggs are porous at the equator zone, while in the pole based on synapomorphic characters. These authors compared these 95 materials with those from Sanagasta, which present the filispherulithic on average, a little smaller; in Auca Mahuevo the eggs have diameters morphotype. In the figures the material looks like megaloolithids eggs of 13 to 15 cm (Chiappe et al., 1998), while in Río Negro they rarely but, for a detailed description, this material will need a thin section. exceed 14 cm in diameter. The Auca Mahuevo material lacks clear limits between units, and In the case of the faveoloolithids found in Río Negro, diameters tubocanaliculated pore-canals, which differentiates this from the Tama range between 17 and 21 cm; even, as we saw, different egg sizes material, which has a Y-shaped pattern of vertical pore canals. Without are present within the same group. Is this variation taxonomically the basal cone these materials could be confused with the upper part significant? Surely not, so they have been understood in that way by of filispherulitic materials as happened at the Sanagasta locality. many taxonomists who have incorporated in their diagnoses a wide For a correct assignment, the Tama materials will need a deeper range of variation within oospecies, both for egg size as well as other microstructure and ultrastructure description. There are six oospecies features. If we follow what happens in, for example, ostriches, egg related to titanosaurs in Argentina. In the parataxonomic systematics diameter is directly proportional to the size of the female (Peucker et section it was explained that four oospecies from South America have al., 2005); the same applies in alligators, with the difference that in been described previously in India. This was an amazing find because the alligators eggs are elliptical, in which case the minor axis usually for the first time eggshells from South America were related to the other presents a greater variability, because it is directly related to the size Gondwana subcontinents India and Africa (Fernández and Khosla, of the female (Simoncini, 2011, personal communication). Similarly, 2015). studies indicate that Magellan penguins corresponding to the first Sphaerovum erbeni was described by Mones (1980) based on season, eggs are greater in volume (<2%) than the second eggs of silicified partial eggs. This egg type has been reported from the Asencio oviposition (Rafferty et al., 2005). Formation. Some authors stated the relationship of Sphaerovum erbeni The titanosaur nests of Auca Mahuevo have a simple architecture. with the oofamily Faveoloolithidae (Faccio, 1994; Casadío et al., 2002). As has been previously discussed, these dinosaurs laid their eggs in However, because the original material consists of diagenetically hollows dug in the ground, which have a characteristic rim; this altered samples, Grellet-Tinner and Fiorelli (2011) argued that it could be established only when researchers could find some sandy should be considered a nomen dubium. Nevertheless, the similarity of depressions made in fluvial channels (surely dry), covered with clay Sphaerovum erbeni with the only faveoloolithid oospecies known from (Chiappe et al., 2004). The Auca Mahuevo nests are sub-circular to sub- Argentina, Paquiloolithus rionegrinus (Simón, 1999, 2006), suggests elliptical, and are between 1 and 1.4 m in diameter along the major that both oospecies are the same. Paquiloolithus salitralensis is the axis, with depths ranging from 10 to 18 cm. On the basis of anatomical most widespread oospecies distributed in South America. In Table 6 all and biomechanical possibilities, Apesteguía (2004) interpreted that characters studied have been described, so we can appreciate that the titanosaurs used their fore legs to make these excavations. macro- and microstructure represent the same kind of egg, and it means Normally, the Auca Mahuevo nests have between 15 and 35 eggs, that the same group of dinosaurs were reproducing in Argentina and which are stacked in layers in no apparent order (Chiappe et al., 2004). Uruguay. However, it is evident that those materials belong to the single Jackson et al. (2013) studied the Auca Mahuevo eggs, determining South American faveoloolithid oospecies, Paquiloolithus rionegrinus that vertisols have moved and accumulated several nests, diminishing (Simón, 1999, 2006). different nests. On the other hand, in a few nests carbonized materials Arriagadoolithidae eggs have been considered previously by other were found; hence, Grellet-Tinner (2006) interpreted that they normally authors as elongathoolithid eggs (Salgado et al., 2007, 2009). On the contain a certain amount of vegetation, which facilitated egg incubation basis of their external ornamentation, Salgado et al. (2009) speculated with its decomposition. This interpretation opposes that given by that some of these Elongatoolithidae eggshells belong to alvarezsaurid Jackson et al. (2008), who, based on the low level of conductance of dinosaurs. Later, Agnolin et al. (2012) confirmed this hypothesis on the the Neuquén eggs, postulated that they would not have been covered basis of associated skeletal egg material. Agnolin et al. (2012) described by vegetation. It is in this sense that Simoncini et al. (2014) showed that the ornamentation patterns expressed on the outer shell surface of that during embryo incubation, the eggshell changes to a more porous A. patagoniensis are most reminiscent of those seen in Elongatoolithus condition. Perhaps a different value of water vapor conductance merely and Macroelongatoolithus oospecies (Zhao, 1975; Mikhailov, reflects a different stage of development. 1994; Li et al., 1995; Zelenitsky et al., 2000; Jin et al., 2007). These Vilá et al. (2010) studied three dimensional modeling of the authors compared A. patagoniensis with Continuoolithus canadensis dinosaur clutches from the Upper Cretaceous Pinyes locality. These (Zelenitsky et al., 1996) and Triprismatoolithus stephensi (Jackson and authors present a more detailed taphonomic study of megaloolithid Varricchio, 2010), concluding that A. patagoniensis substantially differs eggs providing more accurate information on clutch geometry and from all Elongathoolithidae and C. canadensis by the presence of three reproductive behavior. These authors describe clutches from Pinyes structural layers of calcite, differing in the surface ornament and other where they exhibit up to 28 eggs in three superimposed levels, and the characters (e.g., shell thickness mammillary/prismatic layer thickness eggs occur in linear and grouped patterns within an elongate, shallow, ratio of 1:5 in Elongatoolithus; Zhao,1975; Wang et al., 2010). These bowl-shaped depression. Vilá and colleagues suggested that 25 eggs authors concluded that this new material represents a new oospecies may represent a typical megaloolithid clutch size; while small egg and oofamily related with alvarezsaurid non-avian dinosaurs (Agnolin clusters that display linear or grouped egg arrangements reported at et al., 2012). Pinyes and other localities likely reflect recent erosion, as they explain Laevisioolithidae eggs have been related to Ornithothoracena birds in their article. The distinct clutch geometry reported at Pinyes and by a very confident association of eggshell with embryo (Schweitzer other megaloolithid localities worldwide strongly suggest a common et al., 2002). The Neuquén city eggs represent a new material with reproductive behavior that resulted from the use of the hind foot for a four-layered eggshell, which have been included in the parafamily scratch-digging during nest excavation as was presented in Salgado et Laevisioolithidae. Marsola et al. (2014) described the first fossil avian al. (2007) and Coria et al. (2010). The Río Negro clutch presents the egg from Brazil, which was discovered in Upper Cretaceous strata same geometry reported by Vilá but with a more compressed structure of São Paulo. These authors discussed the close similarity between described as kidney shaped, indicating the same strategy for nest the Brazilian bird egg and those of enantiornithines from the Upper construction. Cretaceous Bajo de la Carpa Formation (Río Colorado Subgroup) of Argentina, and this advocates affinity with basal Ornithothoraces. In this Oviposition Strategies regard, the Brazilian materials represent a different ootaxon in relation There are two basic strategies of oviposition in sauropod dinosaurs: to the synapomorphic features and represents one of the thinnest shelled oviposition in groups and linear response. In turn, within each of these Mesozoic avian eggs documented to date. These authors interpreted the categories two subgroups can be distinguished: oviposition in groups, approximately equal thicknesses of L1–L3 in Brazilian eggs to be a two types of arrangements, (1) concentric circular distribution, (2) unique feature of this specimen. Marsola et al. (2014) discussed the inverted cone; and linear ovipositions, (1) parallel rows and (2) arches characters of their material and compared them with Mesozoic avian (Moratalla and Powell, 1994). In Spain, more precisely in Lleida, a nest and non-avian dinosaurs materials, concluding that these eggshells are with six to eight eggs arranged circularly in radial view, which has a more related with enanthiornithid birds than other specimens. conical shape, was recorded (Lapparent, 1958; Kerourio, 1981). On the other hand, in India (Balasinor locality), a variant of the conical Interpretation of Macrocharacters and Nest Structure of nest has been recorded, where there are simple holes with shallow, Megaloolithid and Faveoloolithid Eggs rounded contours (Mohabey, 1984; Sahni and Khosla, 1994), which If we compare the whole evidence from Río Negro with those contain three to six eggs (Moratalla and Powell, 1994). In these cases from the Mahuevo Auca, we find that the Río Negro megaloolithids are, it is unclear whether each nest egg was placed by one or more females. 96 Vilá et al. (2010) presented three types of egg clusters for the Pinyes dinosaures de Rennes-le Château (Aude); premiers résultats de la locality: “Type 1 consists of 20–28 eggs that occur in close association campagne de fouilles 1984. or touching one another. These eggs form a linear and grouped pattern Calvo, J.O., Engelland, S., Heredia, S.E., and Salgado, L., 1997, First in the upper and lower portion of the cluster, respectively. Type 2 record of dinosaur eggshells (?Sauropoda-Megaloolithidae) from consists of moderate to large clusters of 8 to 18 eggs; the geometry and Neuquén, Patagonia, Argentina: Gaia, v. 14, p. 23-32. close egg contact in these egg accumulations are similar to portions of Carpenter, K., 1999, First discoveries. Eggs, nests, and baby dinosaurs; Type 1 clusters. Finally, Type 3 clusters include small accumulations of in Carpenter, K., Hirsch, K.F., and Horner, J., eds., Dinosaur eggs up to 5 eggs.” These authors discussed previous descriptions made by and babies. New York: Cambridge University Press, p. 1-5. Moratalla and Powell (1994) with an inaccurate interpretation. Casadío, S., Manera, T., Parras, A. and Montalvo, C., 2002, Huevos de In Bajo de Santa Rosa, Río Negro Province, Argentina, several dinosaurios (Faveoloolithidae) del Cretácico Superior de la cuenca clusters of Paquiloolithus salitralensis were mapped. Some of them del Colorado, provincia de La Pampa, Argentina: Ameghiniana, v. were arranged in a circle but randomly, whereas others are also aligned 39(3), p. 285-293. randomly (Powell, 1992). Carroll. R.C., 1997, Patterns and Processes of Vertebrate Evolution. The second type of breeding strategy is registered at Rennes- Cambridge University Press. Cambridge. Le-Chateau, France (Breton et al., 1986; Coombs, 1989). In this Chassagne-Manoukian, M., Haddoumi, H., Cappetta, H., Charrière, deposit, eggs are not grouped, but aligned in arcs with a radius that A., Feist, M., Tabuce, R. and Vianey-Liaud, M., 2013, Dating ranges between 1.3 to 1.7 m. Each arc contains between 15 to 22 eggs the “red beds” of the Eastern Moroccan High Plateaus: Evidence (Breton et al., 1986; Coombs, 1989). These bows could correspond to from late Late Cretaceous charophytes and dinosaur eggshells: the radius of rotation of a crouched female laying her eggs (Moratalla Geobios, v.46, p.371-379. DOI: http://dx.doi.org/doi:10.1016/j. and Powell, 1994); thereby, variations in the radii of the arcs could be geobios.2013.06.001 related to the size of the female (Breton et al., 1986). Within these arcs Chiappe, L.M., Coria, R.A., Dingus, L., Jackson, F., Chinsamy, A.and occasionally appear clusters of eggs, which were initially attributed to Fox, M., 1998, Sauropod dinosaur embryos from Late Cretaceous ornithopods, on the grounds that these dinosaur remains were found of Patagonia: Nature, v. 396, p. 358-361. at the stratigraphic levels of the eggs (Cousin et al., 1994), although Chiappe L.M, Salgado, L. and Coria, R.A., 2001, Embryonic skulls of it is likely that they also correspond to titanosaurs (Moratalla and titanosaur sauropod dinosaurs: Science, v. 293, p. 2444-2446. Powell, 1994). Dughi and Sirugue (1966) described a group of eggs Chiappe, L.M., Schmitt, J.G., Jackson, F.D., Garrido, A., Dingus, arranged in rows; in this particular case there were more than six lines L. and Grellet-Tinner, G., 2004, Nest structure for sauropods: of eggs (Moratalla and Powell, 1994). Vilá et al. (2010) claim that the Sedimentary criteria for recognition of dinosaur nesting traces: arc pattern has been questioned by some workers (Sander et al., 2008; Palaios, v. 19, p. 89-95. Carpenter 1999). Coria, R.A., Salgado, L. and Chiappe, L.M., 2010, Multiple dinosaur The Río Negro clutches show different patterns in egg laying; from egg-shell ocurrence in a Upper Cretaceous nesting site from the typical kidney forms observed in the Pyrenees and Auca Mahuevo Patagonia: Ameghinana, v. 47, p. 107-110. (in the case of megaloolithids), to simple alignments or groups, in Coria, R.A. and Chiappe, L.M., 2007, Embryonic skin from Late the case of faveoloolithid eggs. In the latter case, greater variability Cretáceous sauropod (Dinosauria) of Auca Mahuevo, Patagonia, occurs in the number of eggs per clutch, although it is unclear if this Argentina: Journal of Paleontology, v. 81, p. 1528-1532. is due to reasons of a taphonomic order, or is the result of a particular Cousin, R., Breton, B., Fournier, R. and Watté, 1994, Dinosaur egg reproductive behavior of the female (Salgado et al.. 2007; Coria et al., laying and nesting in France; in Carpenter, K., Hirsch, K.F., and 2010). Horner, J., eds., Dinosaur eggs and babies. New York: Cambridge University Press, p.56-74. ACKNOWLEDGMENTS Cousin, R. and Breton, G., 2000, A precise and complete excavation First and foremost, I would like to express my gratitude to Dr. is necessary to demonstrate a dinosaur clutch structure; in Bravo, Leonardo Salgado, for his guidance on different levels that truly A.M. and Reyes, T, eds., First International Symposium on contributed to the completion of this research. This work was funded Dinosaur Eggs and Babies, Isona I Conca Della`Catalonia, Spain, by PICT 2006-00357 and PICT 2013-1901. Also, I would like to thank p. 31-42. Dr. Ignacio Cerda, and Dr. Rodolfo García for their friendship and help Curtis, H. and Barnes, N.S., 1993, El reino animal IV: los during this research. Thanks to Liliana Berthe, Daniel Cabaza for their deuterostomados. Biología. Editorial Médica Panamericana, 1199 great help on the field trips to Bajos de Santa Rosa. Spencer G. Lucas p. edited the English language of the manuscript. Finally, I thank the Deeming, D.C., 2002, Avian Incubation: Behaviour, Environment and Universidad Nacional del Comahue and CONICET. The authors thank Evolution. Oxford University Press, Oxford, 421 p. three reviewers Moreno-Azanza Miguel, García-Sellés Albert and Deeming, D.C., 2006, Ultra structural and functional morphology of Salgado Leonado for their critical comments, which have considerably eggshells supports the idea that dinosaur eggs were incubated improved the manuscript. I would like to thank Ashu Khosla for inviting buried in a substrate: Palaeontology, v. 49, p. 171-185. me to write a paper and participate in this book. Dughi, R. and Sirugue, F., 1966, Sur la fossilization des oeufs de dinosaurs: Comptes rendus des Séances de l´Academie des REFERENCES Sciences, v. 262, p. 2330-2332. Agnolin, F.L., Powell, J.E., Novas, F.E. and Kundrátand Martin, 2012, Ferguson, M., 1985, Reproductive biology and embryology of New alvarezsaurid (Dinosauria, Theropoda) from uppermost cocodrilians; in Billet, F. and Gans, C.,eds., Biology of the Cretaceous of north-western Patagonia with associated eggs: Reptilia, v. 14, p. 330-491. 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Khosla, A. and Sahni, A., 1995, Parataxonomic classification of Salgado, L., Magalhães Ribeiro, C., García, R.A. and Fernández, Late Cretaceous dinosaur eggshells from India: Journal of the M., 2009, Late Cretaceous megaloolithid eggs from Salitral de Palaeontological Society of India, v. 40, p. 87-102. Santa Rosa (Río Negro, Patagonia, Argentina) inferences on the Khosla, A. and Sahni, A., 2003, Biodiversity during the Deccan titanosaurian reproductive biology: Ameghiniana, v. 46, p. 605- volcanic eruptive episode: Journal of the Asian Earth Sciences, v. 620. 21, p. 895–908. Schweitzer, M., Jackson, F.D., Chiappe, L.M., Schmitt, J.G., Calvo, Khosla, A. and Verma, O., 2015, Paleobiota from the Deccan volcano- J.O. and Rubilar, D.E. 2002, Late Cretaceous avian egg with sedimentary sequences of India: paleoenvironments, age and embryo from Argentina: Journal of Vertebrate Paleontology, v. 22, paleobiogeographic implications: Historical Biology, v. 27, p. p. 192-195. 898–914. Sellés, A.G., Bravo, A.M., Delclòs, X., Colombo, F., Martí X., Ortega- Kundrát, M., Cruickshank, A.R.I., Manning, T.W. and Nudds, J., 2008, Blanco J., Parellada, C. and Galobart, À., 2013, Dinosaur eggs in Embryos of therizinosauroid theropods from the Upper Cretaceous the Upper Cretaceous of the Coll de Nargó area, Lleida Province, of China: Diagnosis and analysis of ossification patterns. Acta south-central Pyrenees, Spain: Oodiversity, biostratigraphy and Zoologica doi: 10.1111/j.1463-6395.2007.00311.x their implications: Cretaceous Research, v. 40, p. 10-20. Lapparent, A.F., 1958, Découverte d´un gisement d´oeufs de Seymour, R.S., 1979, Dinosaur egg: Gas conductance through the shell, Dinosauriens dans le Crétecé supérieur du bassin de Tremp water loss during incubation and clutch size: Paleobiology, v.5, p. (Province de Lérida, Espagne) : Comptes Rendus des Séance de 1–11. l´Académie des Sciences, v. 247, p. 247. Simón, M. E., 1999, Estudio De Fragmentos De Cáscaras De Huevos Manera de Bianco, T., 1996, Nueva localidad con nidos y huevos de De La Formación Allen (Campaniano-Maastrichtiano), Provincia dinosaurios (Titanosauridae) del Cretácico Superior, Cerro Blanco, De Río Negro, Argentina. Unpublished Graduation Dissertation, Yaminué, Río Negro, Argentina: Asociación Paleontológica Universidad Nacional de Córdoba, Córdoba, 249 p. Argentina. Publicación Especial 4 1º Reunión Argentina de Simón, M.E., 2006, Cáscaras de huevos de dinosaurios de la Formación Icnología, p. 59-67. Allen (Campaniano-Maastrichtiano), Salitral Moreno, provincia Magalhães Ribeiro, C.M., 1997, Descripςao de caracteres morfológicos de Río Negro, Argentina: Ameghiniana, v. 43, p. 513-528. e estudo composicional de cascaras de ovo de dinossauros da Simoncini, M.S., Fernández, M.S. and Iungman, J., 2014, Cambios Formaςao Allen (Cretáceo Superior), do Bajo de Santa rosa, estructurales en cáscaras de huevos de Caiman latirostris Structural 98 changes in eggshells of Caiman latirostris. Revista Mexicana de (Cretácico Superior) de la provincia de La Rioja, Argentina: Biodiversidad 85: 78-83, DOI: 10.7550/rmb.36240 Ameghiniana, v. 44, p. 11-28. Soto, M., Perea, D., and Cambiaso, A., 2011, First sauropod (Dinosauria: Vilá, B., Jackson, F.D., Fortuny, J., G. Sellés, A., Galobart, Á, 2010, Saurischia) remains from the Guichón Formation, Late Cretaceous 3-D modelling of megaloolithid clutches: Insights about nest of Uruguay: Journal of South American Earth Sciences, v. 33, p. construction and dinosaur behaviour: PLoS ONE 5(5): e10362. 68-79. doi:10.1371/journal.pone.0010362 Tauber, A.A., 2007, Primer yacimiento de huevos de dinosaurios

APPENDIX

TABLE 1. Characters compared between the synonimized oospecies. Authors Egg shape Egg diameter Eggshell Thickness Height/width ratio

M. jabalpurensis (Khosla and Sahni, Spherical 140–160mm Range: 1.0–1.75mm (Bara Simla 2.45:1 1995) Hill, Patbaba); Ridge: 1.0–1.50mm (Jabalpur, Madhya Pradesh); Padiyal: 1.20–1.66mm (Dhar District, Madhya Pradesh); Bagh Cave: 1.33–1.75mm (Dhar District, Madhya Pradesh); Dholiya: up to 2.38mm (Dhar District, Madhya Pradesh) M. matleyi (Mohabey, 1998) Spherical 160–180mm Pavna: 1.50–1.80mm (Chandrapur 3:01 District, Maharashtra) and Patbaba Ridge (Jabalpur, Madhya Pradesh). M. patagonicus (Calvo, Engelland, Probably 160mm Bajo de la Carpa Formation: 1.70– 3.66:1 Heredia and Salgado, Spherical 2.1mm (Neuquén City, Argentina); 1997) Tipo 1 b Fernández, 2013 Subspherical 160mm Allen Formation: 1.8–2.6mm 3.72:1 (Mansilla I y II, Bajos de Santa Rosa, Río Negro) 99 Previous descriptions Previous Previously described as (Mohabey 1984); Type-2 (Sahni et Type-I Titanosaurid al. 1994) Previously described as (Srivastava et Type-B Kheda Titanosaurid al. 1986) and (?) (Sahni et al. 1994) Type-I Referred to Titanosaurid Referred to Titanosaurid (Sahni et al. 1994) in Type-I Fernández 2013) Small Small Basal caps diameter diameter) Basal caps (0.2–0.5mm in Subcircular basal Medium sized and caps 0.1–0.5mm in subcircular in shape units Shape of spherolith and some time Shell units long compressed and to adjacent units some time-fused fused to adjacent Long and straight Shape of spherolith Cylindrical Cylindrical Cylindrical 9.6:1 ratio 6.42: 1 Height/width 4:01 4:01 3.5:1 ratio Height/width Gujarat Argentina). Eggshell Thickness 4.43 (Berthe II, egg level 5; Bajos de Santa Rosa, Río Negro, and Daulatpoira (Kheda District), Eggshell Thickness 4.0–4.80 mm; Dholidhanti and Paori 4.1–4.9mm with average thickness of in Dohad area of Panchmahal District, Range: 1.70–3.50mm (Jabalpur, Range: 1.70–3.50mm (Jabalpur, Madhya Pradesh); Patbaba ridge: Madhya 2.10–2.52mm (Jabalpur, Pradesh); Dholiya: 2.10–2.45mm (Dhar District, Madhya Pradesh); 2.24–2.52mm (Jhabua Walpur: District, Madhya Pradesh); Balasinor: India) Western 2.87–3.50mm (Gujarat, 2.80–3.50mm (Rahioli, Gujarat) Range: 3.4–3.6mm with average VI egg V, thickness of 3.5 (Berthe Allen Formation, Río Negro) level 4, eggshells 130–180mm Fragmentary Egg diameter Unknown 120–200mm 125–160mm Egg diameter eggshells Spherical Egg shape Fragmentary Eggshell Spherical Spherical fragments Egg shape Author 2013 1998 Author Mohabey, Mohabey, Mohabey, 1998 Mohabey, Fernández, Khosla and Sahni, 1995 Fernández, 2013 Tipo 1e Tipo M. megadermus TABLE 3. Characters compared between the synonymized oospecies TABLE TABLE 2. Characters compared between the synonymized oospecies. TABLE M. cylindricus Tipo 1d Tipo M. rahioliensis 100

TABLE 4. Characters compared between the synonymized oospecies. Authors Egg shape Egg diameter Eggshell Height/width Previous description Thickness ratio F. baghensis Khosla and Sahni, Spherical 140–200mm 1.0–1.70mm 2.32:1 Previously described as 1995 Kheda Type-A (Srivastava et al. 1986) and (?) Titanosaurid Type-III (Sahni, 1993; Sahni et al. 1994) M. balasinorensis Mohabey, 1998 Spherical 140–180mm 1.45–1.65mm 2:01 Previously described as Kheda Type-A (Srivastava et al. 1986) M. pseudomamillare Vianey-Liaud, Spherical 190–210mm 1.0–2mm -- Previously known from Aix Hirsch, Sahni and Basin, France, Peru and Sigé, 1997 Bolivia (Vianey-Liaud et al. 1994, 1997; Vianey-Liaud and Martinez, 1997) Patagoolithus Simón 2006 Spherical to sub- 130–150mm 1.05–1.61mm 2.28:1 Previously described by Auca salitralensis spherical (Chiappe et al. (Simón, 2006); Mahuevo Megaloolithid type (Chiappe et al. 1998) 1.00–1.78mm associated with sauropod 1998) (Chiappe et al., dinosaur (Chiappe et al. 1998) 1998); Patagoolithus salitralensis Simón, 2006, Santa Rosa Type-2A (Salgado et al. 2007, 2009) Tipo 1a (Fernández, 2013)

TABLE 5. Characters compared between the synonymized oospecies. Authors Egg shape Egg Eggshell Ornamentation Description Height/width diameter Thickness range ratio

F. berthei Fernández and unknown unknown 2.45 to 2.9mm Compactituberculate Fan-shaped units which 3.29:1 Khosla 2015 average node diameter are variable. The upper about 0.66mm with and external parts of diameter ranging the units have a wide from 0.3 to 0.7 difference with the mm ornamentation inner parts width and (subcircular nodes) shape; lateral margins of spheroliths are conical and non-parallel, and the eggshell units are partially fused. Tipo 1c Fernández 2013 unknown unknown 2.45 to 2.9mm The same as F. berthei The same as F. berthei The same as F. berthei 101 Histostructure Compactituberculate Ornamentation / Morphotype filiespherulitic / convex growth lines parallel to the outer surface / multicanaliculate pore system Compactituberculate ornamentation/ filiesferulitic morphotype/ multicanaliculate pore system Compactituberculate ornamentation Compactituberculate ornamentation/ filiespherulitic morphotype/ multicanaliculate pore system Ornamentation is typically compactituberculate (i.e., external surface covered with dome-like tubercles); multicanaliculate pore system. Eggshell external surfaces exhibit rounded or subrounded to subpolygonal nodular structures/ display an exceptionally well- developed pore canal network giving them a spongy appearance/ rounded or subrounded to subpolygonal nodular structures Basic type dinosauroid-spherulitic/ Morphotype filiespherulitic/ Compactituberculate ornamentation/ Multicanaliculate pore system Smooth surface or slightly rough/ thin eggshells Smooth or slightly rough surface, thin eggshells Compactituberculate ornamentation / Morphotype filiespherulitic / convex growth lines parallel to the outer surface / multicanaliculate pore system Silicified microstructure Compactituberculate ornamentation / Morphotype filiespherulitic / convex growth lines parallel to the outer surface / multicanaliculate pore system Site Salitral Moreno Formación Allen, Formación Bajos de Santa Rosa. Probably the same Ootaxon Guichón Formation (Late Cretaceous) Sanagasta, Cretácico Formaction superior. Los Llanos Bajos de Santa Arriagada III Rosa y China and Mongolia China Salitral Moreno Fm. Asencio Uruguay Soriano and Algorta, Fm. de Uruguay, Mercedes Late Cretaceous Egg diameter 21 cm 17.5- 20 cm; Spherical eggs Probably coming from spherical eggs ~ 21 cm diameter Spherical eggs with a diameter of 18 to 21cm 13.6- 12.4 mm ellipsoidal and small eggs Dm 17.5 and dm 9mm 21 cm 15- 20,6 cm Spherical eggs, with compactituberulata ornamentation 17- 20 cm diameter 0.22- 1.12 mm Mammila mm 0.22- 1.12 mm Node 0.22- 0.90mm diameter similar al tipo 2 0.3-1.1mm 0.2- 1.1 0.3-1.1mm 0.22- 0.90 mm 0025-1.7 unit the shell Width of Width 0.18- 1.08 mm 0.3- 1 mm 0.3- 1 mm 0.18- 1.08 mm Mean 5.51mm Thicknes 4.89 mm up to 5 mm thick 5.21 mm 3.847 mm 5.21 mm 5.51 mm 3.85- 6.70 mm Thickness 4.2 and 5.5. mm, 3.3- 5.5mm 3.5- 7.5mm 1.29 to 7.94 mm 3.5- 7.5 mm 2.20- 2.40 mm 1.38- 1.75mm 3.85-.6.70 mm 4.2- 5.5 mm 2.5- 5 mm Author Simón 2002 Soto et al. 2012 Manera de Bianco, 1996 Magalhaes Ribeiro 1997 Grellet-Tinner and Fiorelli 2011 Fernández 2011 Zhao and Ding, 1976 Zhao, 1979 Simón, 2006 Mones, 1980 Faccio, 1994 Casadío et al., 2002 Sphaerovum Paquiloolithus rionegrinus TABLE 6. Characters compared between the synonymized oospecies. TABLE Similitudes con materiales de Cerro Blanco, Yaminue Bajos de Santa A Motfotipo Rosa Faveoloolithidae, Faveoloolithid egg Tipo 2 Tipo ningxiaensis F. xiaguanensis Youngoolithus Zhao, 1979 Oofamilia ?Faveoloolithidae et ooespecie indet Oogenero Spherovum erbeni Oofamilia Faveoloolithidae Materiales de La Pampa, 102 Age / Formation Allen Formation (Upper Cretaceous), Campaniano- Maastrichtiano Allen Formation (Upper Cretaceous), Campaniano- Maastrichtiano. (Arriagada III, egg level 2 Upper Cretaceous, Campanian. Bajo de la Carpa Member of the Rio Colorado Formation, Neuquén City. Upper Cretaceous deposits do Rio Vale of the Peixe Formation in the Bauru Group of São Paulo Description Three layers (external, prismatic, mammillary). Ornamentation low irregular shaped nodes, isolated node-like ridges, and low long ridges interconnected with each other to form a net, thus the combination of plexi-ramo-tuberculate and unique dendro-reticulate ornament may represent autapomorphic character of this oospecies. tubocanaliculate and obliquicanaliculate pore system with funnel-like openings on the outer surface Two layers (mammillary and prismatic).The Two outer surface is composed of crests about 0.8 mm high but sometimes reaching 2.4 mm, exhibiting a typical linearituberculate There are also some isolated ornamentation. nodules of about 0.48 mm diameter; Well- mammillary cones are compacted. developed; mammillary layer composed of well-defined wedges of radial calcite crystals, cores at their base with organic Compact shell units with trilaminated arrangement of calcite crystals. Elongated mammillary cones. Mammillary layer is 91μm thick, comprising 1/3 of the total eggshell. Prismatic columns with non sharp limit between mammillary and second layer. Third 37μm thick, the external layer has more compact appearance and squamatic texture than the second layer. The shell itself is 125.5 μm thick and externally smooth with rounded pore Three structural layers average 38 openings. μm in L1, 42 L2, and 45.5 L3. These extend close to the L1‒L2 boundary The and form a semi-circle around core. graded contact between L1 and L2 forms prismaticspherulites that are present at the base of each shell unit and are composed blade-shaped calcite crystals. Egg shape Eggs with a diameter of ca. 70mm (?maximum width) and unknown length unknown Asymmetric in profile with one end slightly more pointed than the other Slightly compressed, with its main axes measuring 31.4 mm versus 19.5 1mm 260μm 125.5-μm Thickness 1.1 to 1.2 mm. Author Kundrát, Novas, Agnolin and Powell, 2012 Salgado et al. 2007 Schweitzer et al. 2002 Marsola et al., 2014 Oofamily Arriagadoolitidae Elongatoolithidae Laevisioolithidae Laevisioolithidae Arriagadoolithus salitralensis TABLE 7. Characters compared between the synonymized oospecies. TABLE Type 3 Type Ornithothorecean Ornithothoraces 103 TABLE 8. Distribution per site and level of the dinosaur oospecies from Río Negro Site Egg Level F. baghenisis M. jabalpurensis F. berthei M. M. Paquiloolithus Arriagadoolithus cylindricus megadermus salitralensis rionegrinus Mansilla I 3 x x x Mansilla II 3 x x x Cº Bonaparte 2 x SE Cº Bonaparte 2 x Berthe II 1 x Berthe II 1 x Berthe III 2 x x Berthe IV 3 x x Berthe V 4 x x Berthe VI 4 x x García I 5 x x Santos I 2 x Santos II 3 x Santos II A 3 x Santos II B 3 x x Santos III 3 x Arriagada I 4 x x Arriagada III 2 x x x 104 TABLE 9. Description of paleoenvironment, age and formation for each kind of eggshell described in South America. Localities Age Formation Oospecies Paleoenvironments Taxonomic Authors group Rio Negro Salitral de Santa Campanian- Allen M. jabalpurensis, Brackish lagoonal and Titanosaur Salgado et al. 2007, Rosa Maastrichtian M. cylindricus, M. supratidal environments, 2009; Fernández, megadermus, F. associated with eolian sands 2011 and Fernández berthei, F. baghensis, which form dunes and and Khosla, 2015 Paquiloolithus deposits of ephemeral rivers rionegrinus Salitral Moreno Campanian- Allen Paquiloolithus Titanosaur Simón, 2006 Maastrichtian rionegrinus Salitral Ojo de Campanian- Allen Paquiloolithus Brackish lagoonal and Titanosaur and Salgado et al. 2007, Agua Maastrichtian rionegrinus supratidal environments, Alvarezsaurids 2009, Fernández, associated with eolian sands 2011, Agnolin et al. which form dunes and 2012 and Fernández deposits of ephemeral rivers and Khosla, 2015 Yaminué Campanian- Allen Paquiloolithus Titanosaurs Manera de Bianco et Maastrichtian rionegrinus al. 2002 Neuquén Neuquén City Middle-Upper Megaloolithus Eolian deposition that created Titanosaurs and Calvo et al. 1997; Santonian jabalpurensis, large dunes and inter-dune Ornithothoracine Schweitzer et al. Laevisioolithidae lagoon basins skirted by 2002, Fernández et fluvial deposits, criss-crossed al. 2014 by streams and seasonal or ephemeral water bodies Auca Mahuevo Coniacian to Fusioolithus baghensis Titanosaurs Fernández and Campanian Khosla, 2015 La Rioja Sanagasta Los Llanos Faveoloolithid Cretaceous hydrothermal Titanosaurs Grellet-Tinner and site at Sanagasta, La Rioja Fiorelli, 2011 Province, Argentina Chubut Huaniman Albian-Aptian Cerro BarcinoMegaloolithid The egg materials were found Titanosaurs Argañaraz et al., in fine tuffaceous sandstone 2013 from a proximal floodplain deposit associated with sinuous and multi-episodic river channels, belonging to the Cerro Castaño Member La Pampa Campanian- Los Paquiloolithus Titanosaurs Casadío et al., 2002 Maastrichtian Colorados rionegrinus Uruguay Soriano Faveoloolithid Titanosaurs Faccio, 1994 Algorta Faveoloolithid Titanosaurs Faccio, 1994 20 km SE of Late Cretaceous Guichón Faveoloolithidae, Fluvial environments,warm, Titanosaurs Soto et al., 2012 Quebracho Formation Sphaerovum semiarid and humid town, Paysandú paleoclimatic conditions. province, Uruguay Brazil Minas Gerais Uberaba? Megaloolithus Titanosaurs Grellet-Tinner and Hussam Zaher, 2007, Maghalaes-Ribeiro, 2002 105 TABLE 10. Localities, age and formations from which have been described each oospecies Localities Age-Formation Authors

Paquiloolithus rionegrinus Salitral Moreno, Salitral Ojo Allen Formation: Upper Cretaceous, Campanian- Simón, 2002, 2006 de Agua, Bajos de Santa Rosa, Maastrichtian, Los llanos: Upper Cretaceous?. Yaminué, Sanagasta, Soriano, Los Colorados: Campanian-Maastrichtian Algorta, La Pampa

Megaloolithus jabalpurensis Neuquen City, Bajos de Santa Upper Cretaceous. Bajos dela Carpa Formation. Khosla and Sahni, 1995 Rosa Allen Formation, Campanian-Maastrichtian

Megaloolithus megadermus Bajos de Santa Rosa Upper Cretaceous. Allen Formation: Campanian- Mohabey, 1998 Maastrichtian Megaloolithis cylindricus Bajos de Santa Rosa Upper Cretaceous. Allen Formation: Campanian- Khosla and Sahni, 1995 Maastrichtian Fusioolithus baghensis Auca Mahuevo Upper Cretaceous Khosla and Sahni, 1995 Anacleto Formation (Campanian) of Patagonia, Fernández and Khosla, Argentina 2015 Fusioolithus berthei Bajos de Santa Rosa Upper Cretaceous. Allen Formation, Campanian- Fernández and Khosla, Maastrichtian 2015

Arriagadoolithus rionegrinus Salitral Ojo de Agua: Upper Cretaceous. Allen Formation, Campanian- Agnolin et al. 2012 Arriagada III Maastrichtian

Laevisioolithidae Neuquen City, Brazil Upper Cretaceous: Bajo de la Carpa Formation Schweitzer et al. 2002