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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.

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General pattern in megaloolithid clutches.(A)–Field photograph of partially excavated titanosaur nest (NE-01) from Auca Mahuevo locality, Argentina. Scale bar  = 15 cm. (B)–Scheme for the same nest (C)–Pinyes clutch (18E02) morphology inferred after the 3-D model. Note the strong similarity in the elongated kidney-like shape in all three figures. (D)–Published field map and interpreted nest structure in South America (SAM). Modified from Chiappe et al. [37], [75]. (E)–Same for megaloolithid eggs from India (IND). Modified from Mohabey [3], [29]. (F)–Same for megaloolithid eggs from Europe (EUR). Scale bar  = 15 cm (A–C) and 1 meter (D–F).
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pone-0010362-g006: General pattern in megaloolithid clutches.(A)–Field photograph of partially excavated titanosaur nest (NE-01) from Auca Mahuevo locality, Argentina. Scale bar  = 15 cm. (B)–Scheme for the same nest (C)–Pinyes clutch (18E02) morphology inferred after the 3-D model. Note the strong similarity in the elongated kidney-like shape in all three figures. (D)–Published field map and interpreted nest structure in South America (SAM). Modified from Chiappe et al. [37], [75]. (E)–Same for megaloolithid eggs from India (IND). Modified from Mohabey [3], [29]. (F)–Same for megaloolithid eggs from Europe (EUR). Scale bar  = 15 cm (A–C) and 1 meter (D–F).

Mentions: The pattern of egg distribution in clutches at Pinyes sites 18E02 and 17E04-B resembles that of titanosaurs clutches from the Auca Mahuevo locality in Argentina that contain a similar number of eggs. However, the maximum length for nesting traces at the Auca Mahuevo site is 100–140 cm, which includes the surrounding rim [37], [75], whereas the length for Pinyes clutches (based on the eggs alone) is approximately 230 cm. Nevertheless, the general shape of Pinyes clutches is remarkably similar to the elongate or kidney-shaped structures documented at the Argentine locality (Fig. 6A–C). The general, elongated egg arrangement at the Pinyes site is also similar to several clutches reported in South America and India (Table 2) (Fig. 6D–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)

General pattern in megaloolithid clutches.(A)–Field photograph of partially excavated titanosaur nest (NE-01) from Auca Mahuevo locality, Argentina. Scale bar  = 15 cm. (B)–Scheme for the same nest (C)–Pinyes clutch (18E02) morphology inferred after the 3-D model. Note the strong similarity in the elongated kidney-like shape in all three figures. (D)–Published field map and interpreted nest structure in South America (SAM). Modified from Chiappe et al. [37], [75]. (E)–Same for megaloolithid eggs from India (IND). Modified from Mohabey [3], [29]. (F)–Same for megaloolithid eggs from Europe (EUR). Scale bar  = 15 cm (A–C) and 1 meter (D–F).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0010362-g006: General pattern in megaloolithid clutches.(A)–Field photograph of partially excavated titanosaur nest (NE-01) from Auca Mahuevo locality, Argentina. Scale bar  = 15 cm. (B)–Scheme for the same nest (C)–Pinyes clutch (18E02) morphology inferred after the 3-D model. Note the strong similarity in the elongated kidney-like shape in all three figures. (D)–Published field map and interpreted nest structure in South America (SAM). Modified from Chiappe et al. [37], [75]. (E)–Same for megaloolithid eggs from India (IND). Modified from Mohabey [3], [29]. (F)–Same for megaloolithid eggs from Europe (EUR). Scale bar  = 15 cm (A–C) and 1 meter (D–F).
Mentions: The pattern of egg distribution in clutches at Pinyes sites 18E02 and 17E04-B resembles that of titanosaurs clutches from the Auca Mahuevo locality in Argentina that contain a similar number of eggs. However, the maximum length for nesting traces at the Auca Mahuevo site is 100–140 cm, which includes the surrounding rim [37], [75], whereas the length for Pinyes clutches (based on the eggs alone) is approximately 230 cm. Nevertheless, the general shape of Pinyes clutches is remarkably similar to the elongate or kidney-shaped structures documented at the Argentine locality (Fig. 6A–C). The general, elongated egg arrangement at the Pinyes site is also similar to several clutches reported in South America and India (Table 2) (Fig. 6D–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