Limits...
3-D modelling of megaloolithid clutches: insights about nest construction and dinosaur behaviour.

Vila B, Jackson FD, Fortuny J, Sellés AG, Galobart A - PLoS ONE (2010)

Bottom Line: Megaloolithid eggs have long been associated with sauropod dinosaurs.Tectonic deformation in the study area strongly influenced egg size and shape, which could potentially lead to misinterpretation of reproductive biology if 2D and 3D maps are not corrected for bed dip that results from tectonism.The distinct clutch geometry at Pinyes and other localities likely resulted from the asymmetrical, inclined, and laterally compressed titanosaur pes unguals of the female, using the hind foot for scratch-digging during nest excavation.

View Article: PubMed Central - PubMed

Affiliation: Institut Català de Paleontologia, Campus de la Universitat Autònoma de Barcelona, Barcelona, Spain. bernat.vila@icp.cat

ABSTRACT

Background: Megaloolithid eggs have long been associated with sauropod dinosaurs. Despite their extensive and worldwide fossil record, interpretations of egg size and shape, clutch morphology, and incubation strategy vary. The Pinyes locality in the Upper Cretaceous Tremp Formation in the southern Pyrenees, Catalonia provides new information for addressing these issues. Nine horizons containing Megaloolithus siruguei clutches are exposed near the village of Coll de Nargó. Tectonic deformation in the study area strongly influenced egg size and shape, which could potentially lead to misinterpretation of reproductive biology if 2D and 3D maps are not corrected for bed dip that results from tectonism.

Methodology/findings: Detailed taphonomic study and three-dimensional modelling of fossil eggs show that intact M. siruguei clutches contained 20-28 eggs, which is substantially larger than commonly reported from Europe and India. Linear and grouped eggs occur in three superimposed levels and form an asymmetric, elongate, bowl-shaped profile in lateral view. Computed tomography data support previous interpretations that the eggs hatched within the substrate. Megaloolithid clutch sizes reported from other European and Indian localities are typically less than 15 eggs; however, these clutches often include linear or grouped eggs that resemble those of the larger Pinyes clutches and may reflect preservation of incomplete clutches.

Conclusions/significance: We propose that 25 eggs represent a typical megaloolithid clutch size and smaller egg clusters that display linear or grouped egg arrangements reported at Pinyes and other localities may represent eroded remnants of larger clutches. The similarity of megaloolithid clutch morphology from localities worldwide strongly suggests common reproductive behaviour. The distinct clutch geometry at Pinyes and other localities likely resulted from the asymmetrical, inclined, and laterally compressed titanosaur pes unguals of the female, using the hind foot for scratch-digging during nest excavation.

Show MeSH
Comparisons of egg arrangements at Pinyes with clutch morphology reported from Europe.(A, C, and E)–Plan view arrangements from Sander et al., [6], Grigorescu et al., [8] and Kérourio [25], and corresponding interpretation of egg arrangements after the Pinyes new clutch morphology, respectively. (B, D, and F)–Lateral view arrangements from the same authors, and interpreted egg arrangements after the Pinyes new clutch morphology, respectively. Scale bar  = 50 cm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC2864735&req=5

pone-0010362-g005: Comparisons of egg arrangements at Pinyes with clutch morphology reported from Europe.(A, C, and E)–Plan view arrangements from Sander et al., [6], Grigorescu et al., [8] and Kérourio [25], and corresponding interpretation of egg arrangements after the Pinyes new clutch morphology, respectively. (B, D, and F)–Lateral view arrangements from the same authors, and interpreted egg arrangements after the Pinyes new clutch morphology, respectively. Scale bar  = 50 cm.

Mentions: Moratalla and Powell [68] summarized megaloolithid nesting strategies reported in the literature and noted three patterns of egg arrangement: 1) circular pattern of 6–8 eggs with random distribution and conical shape, 2) a linear pattern, and 3) eggs arranged in arcs, which if connected would form circles containing fifteen to twenty eggs. However, the arc pattern [69], [70] has been questioned by some workers [6], [7]. The morphology of clutches at Pinyes sites 18E02 and 17E04-B share both similarities and differences with previous descriptions. For example, the linear arrangement of eggs documented at several localities by Sander and colleagues [6], Grigorescu and colleagues [8], and Kérourio [25] (also see Table 2) corresponds to the upper level of 18E02 and 17E04-B (Fig. 5A, C, D). The same authors report grouped arrangements that are comprised of 6–10 eggs that form an inverted cone-shaped arrangement in cross section and include 2–3 superimposed egg levels. This pattern of egg distribution likely corresponds to the lower, deeper level of the Pinyes clutches (Fig. 5B, D–F).


3-D modelling of megaloolithid clutches: insights about nest construction and dinosaur behaviour.

Vila B, Jackson FD, Fortuny J, Sellés AG, Galobart A - PLoS ONE (2010)

Comparisons of egg arrangements at Pinyes with clutch morphology reported from Europe.(A, C, and E)–Plan view arrangements from Sander et al., [6], Grigorescu et al., [8] and Kérourio [25], and corresponding interpretation of egg arrangements after the Pinyes new clutch morphology, respectively. (B, D, and F)–Lateral view arrangements from the same authors, and interpreted egg arrangements after the Pinyes new clutch morphology, respectively. Scale bar  = 50 cm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2864735&req=5

pone-0010362-g005: Comparisons of egg arrangements at Pinyes with clutch morphology reported from Europe.(A, C, and E)–Plan view arrangements from Sander et al., [6], Grigorescu et al., [8] and Kérourio [25], and corresponding interpretation of egg arrangements after the Pinyes new clutch morphology, respectively. (B, D, and F)–Lateral view arrangements from the same authors, and interpreted egg arrangements after the Pinyes new clutch morphology, respectively. Scale bar  = 50 cm.
Mentions: Moratalla and Powell [68] summarized megaloolithid nesting strategies reported in the literature and noted three patterns of egg arrangement: 1) circular pattern of 6–8 eggs with random distribution and conical shape, 2) a linear pattern, and 3) eggs arranged in arcs, which if connected would form circles containing fifteen to twenty eggs. However, the arc pattern [69], [70] has been questioned by some workers [6], [7]. The morphology of clutches at Pinyes sites 18E02 and 17E04-B share both similarities and differences with previous descriptions. For example, the linear arrangement of eggs documented at several localities by Sander and colleagues [6], Grigorescu and colleagues [8], and Kérourio [25] (also see Table 2) corresponds to the upper level of 18E02 and 17E04-B (Fig. 5A, C, D). The same authors report grouped arrangements that are comprised of 6–10 eggs that form an inverted cone-shaped arrangement in cross section and include 2–3 superimposed egg levels. This pattern of egg distribution likely corresponds to the lower, deeper level of the Pinyes clutches (Fig. 5B, D–F).

Bottom Line: Megaloolithid eggs have long been associated with sauropod dinosaurs.Tectonic deformation in the study area strongly influenced egg size and shape, which could potentially lead to misinterpretation of reproductive biology if 2D and 3D maps are not corrected for bed dip that results from tectonism.The distinct clutch geometry at Pinyes and other localities likely resulted from the asymmetrical, inclined, and laterally compressed titanosaur pes unguals of the female, using the hind foot for scratch-digging during nest excavation.

View Article: PubMed Central - PubMed

Affiliation: Institut Català de Paleontologia, Campus de la Universitat Autònoma de Barcelona, Barcelona, Spain. bernat.vila@icp.cat

ABSTRACT

Background: Megaloolithid eggs have long been associated with sauropod dinosaurs. Despite their extensive and worldwide fossil record, interpretations of egg size and shape, clutch morphology, and incubation strategy vary. The Pinyes locality in the Upper Cretaceous Tremp Formation in the southern Pyrenees, Catalonia provides new information for addressing these issues. Nine horizons containing Megaloolithus siruguei clutches are exposed near the village of Coll de Nargó. Tectonic deformation in the study area strongly influenced egg size and shape, which could potentially lead to misinterpretation of reproductive biology if 2D and 3D maps are not corrected for bed dip that results from tectonism.

Methodology/findings: Detailed taphonomic study and three-dimensional modelling of fossil eggs show that intact M. siruguei clutches contained 20-28 eggs, which is substantially larger than commonly reported from Europe and India. Linear and grouped eggs occur in three superimposed levels and form an asymmetric, elongate, bowl-shaped profile in lateral view. Computed tomography data support previous interpretations that the eggs hatched within the substrate. Megaloolithid clutch sizes reported from other European and Indian localities are typically less than 15 eggs; however, these clutches often include linear or grouped eggs that resemble those of the larger Pinyes clutches and may reflect preservation of incomplete clutches.

Conclusions/significance: We propose that 25 eggs represent a typical megaloolithid clutch size and smaller egg clusters that display linear or grouped egg arrangements reported at Pinyes and other localities may represent eroded remnants of larger clutches. The similarity of megaloolithid clutch morphology from localities worldwide strongly suggests common reproductive behaviour. The distinct clutch geometry at Pinyes and other localities likely resulted from the asymmetrical, inclined, and laterally compressed titanosaur pes unguals of the female, using the hind foot for scratch-digging during nest excavation.

Show MeSH