Limits...
New specimens of Nemegtomaia from the Baruungoyot and Nemegt Formations (Late Cretaceous) of Mongolia.

Fanti F, Currie PJ, Badamgarav D - PLoS ONE (2012)

Bottom Line: Nemegtomaia represents the fourth known genus of oviraptorid for which individuals have been found on nests of eggs.All other known oviraptorids from Mongolia and China are known exclusively from xeric or semi-arid environments.However, this study documents that Nemegtomaia is found in both arid/aeolian (Baruungoyot Formation) and more humid/fluvial (Nemegt Formation) facies.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Scienze della Terra e Geologico-Ambientali, Alma Mater Studiorum, Università di Bologna, Via Zamboni, Bologna, Italy. federico.fanti@unibo.it

ABSTRACT
Two new specimens of the oviraptorid theropod Nemegtomaia barsboldi from the Nemegt Basin of southern Mongolia are described. Specimen MPC-D 107/15 was collected from the upper beds of the Baruungoyot Formation (Campanian-Maastrichtian), and is a nest of eggs with the skeleton of the assumed parent of Nemegtomaia on top in brooding position. Much of the skeleton was damaged by colonies of dermestid coleopterans prior to its complete burial. However, diagnostic characters are recovered from the parts preserved, including the skull, partial forelimbs (including the left hand), legs, and distal portions of both feet. Nemegtomaia represents the fourth known genus of oviraptorid for which individuals have been found on nests of eggs. The second new specimen, MPC-D 107/16, was collected a few kilometers to the east in basal deposits of the Nemegt Formation, and includes both hands and femora of a smaller Nemegtomaia individual. The two formations and their diverse fossil assemblages have been considered to represent sequential time periods and different environments, but data presented here indicate partial overlap across the Baruungoyot-Nemegt transition. All other known oviraptorids from Mongolia and China are known exclusively from xeric or semi-arid environments. However, this study documents that Nemegtomaia is found in both arid/aeolian (Baruungoyot Formation) and more humid/fluvial (Nemegt Formation) facies.

Show MeSH

Related in: MedlinePlus

Eggs of Nemegtomaia barsboldi.Details of eggs preserved in the upper layer of eggs in specimen MPC-D 107/15. Scale bar A–E 5 cm.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3275628&req=5

pone-0031330-g010: Eggs of Nemegtomaia barsboldi.Details of eggs preserved in the upper layer of eggs in specimen MPC-D 107/15. Scale bar A–E 5 cm.

Mentions: None of the eggs is preserved in its entirety, and therefore all of the dimensions of an egg cannot be measured accurately (Fig. 9A). Available data on oviraptorid eggs in the literature [5]–[7][20][21][60][63][64] indicate an average length of 17 cm (min = 11.5 cm, max = 25 cm), and a width of 7 cm (min = 5 cm, max = 8.5 cm). By comparison, the most complete eggs found in specimen MPC-D 107/15 are estimate to be 5 to 6 cm wide and 14 to 16 cm long. Preserved eggshells are macroscopically nearly identical to those described by Norell et al. [20], [21] and can be referred to the elongatoolithid oofamily [60], [65], [66], originally considered to be the ornithoid basic type (Figure 10). Eggshells are relatively thin, ranging between 1 and 1.2 mm. The outer surfaces of the eggs are ornamented with linearituberculate ridges and nodes that rise approximately 0.3 mm above the shell (Fig. 10F). Such longitudinal ornamentations do not show any specific trend or variation from the equatorial to apical region. Eggshell microstructure from a total of eight fragments collected from the nest were studied in tangential and radial thin sections, using optical and polarizing light microscopy, and scanning electron microscopy. Unfortunately, all analyzed fragments were heavily altered and re-crystallized calcite, and all histostructures, including pore canals, were obliterated. Furthermore, no pores were observed on the external surfaces of the eggshells.


New specimens of Nemegtomaia from the Baruungoyot and Nemegt Formations (Late Cretaceous) of Mongolia.

Fanti F, Currie PJ, Badamgarav D - PLoS ONE (2012)

Eggs of Nemegtomaia barsboldi.Details of eggs preserved in the upper layer of eggs in specimen MPC-D 107/15. Scale bar A–E 5 cm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3275628&req=5

pone-0031330-g010: Eggs of Nemegtomaia barsboldi.Details of eggs preserved in the upper layer of eggs in specimen MPC-D 107/15. Scale bar A–E 5 cm.
Mentions: None of the eggs is preserved in its entirety, and therefore all of the dimensions of an egg cannot be measured accurately (Fig. 9A). Available data on oviraptorid eggs in the literature [5]–[7][20][21][60][63][64] indicate an average length of 17 cm (min = 11.5 cm, max = 25 cm), and a width of 7 cm (min = 5 cm, max = 8.5 cm). By comparison, the most complete eggs found in specimen MPC-D 107/15 are estimate to be 5 to 6 cm wide and 14 to 16 cm long. Preserved eggshells are macroscopically nearly identical to those described by Norell et al. [20], [21] and can be referred to the elongatoolithid oofamily [60], [65], [66], originally considered to be the ornithoid basic type (Figure 10). Eggshells are relatively thin, ranging between 1 and 1.2 mm. The outer surfaces of the eggs are ornamented with linearituberculate ridges and nodes that rise approximately 0.3 mm above the shell (Fig. 10F). Such longitudinal ornamentations do not show any specific trend or variation from the equatorial to apical region. Eggshell microstructure from a total of eight fragments collected from the nest were studied in tangential and radial thin sections, using optical and polarizing light microscopy, and scanning electron microscopy. Unfortunately, all analyzed fragments were heavily altered and re-crystallized calcite, and all histostructures, including pore canals, were obliterated. Furthermore, no pores were observed on the external surfaces of the eggshells.

Bottom Line: Nemegtomaia represents the fourth known genus of oviraptorid for which individuals have been found on nests of eggs.All other known oviraptorids from Mongolia and China are known exclusively from xeric or semi-arid environments.However, this study documents that Nemegtomaia is found in both arid/aeolian (Baruungoyot Formation) and more humid/fluvial (Nemegt Formation) facies.

View Article: PubMed Central - PubMed

Affiliation: Dipartimento di Scienze della Terra e Geologico-Ambientali, Alma Mater Studiorum, Università di Bologna, Via Zamboni, Bologna, Italy. federico.fanti@unibo.it

ABSTRACT
Two new specimens of the oviraptorid theropod Nemegtomaia barsboldi from the Nemegt Basin of southern Mongolia are described. Specimen MPC-D 107/15 was collected from the upper beds of the Baruungoyot Formation (Campanian-Maastrichtian), and is a nest of eggs with the skeleton of the assumed parent of Nemegtomaia on top in brooding position. Much of the skeleton was damaged by colonies of dermestid coleopterans prior to its complete burial. However, diagnostic characters are recovered from the parts preserved, including the skull, partial forelimbs (including the left hand), legs, and distal portions of both feet. Nemegtomaia represents the fourth known genus of oviraptorid for which individuals have been found on nests of eggs. The second new specimen, MPC-D 107/16, was collected a few kilometers to the east in basal deposits of the Nemegt Formation, and includes both hands and femora of a smaller Nemegtomaia individual. The two formations and their diverse fossil assemblages have been considered to represent sequential time periods and different environments, but data presented here indicate partial overlap across the Baruungoyot-Nemegt transition. All other known oviraptorids from Mongolia and China are known exclusively from xeric or semi-arid environments. However, this study documents that Nemegtomaia is found in both arid/aeolian (Baruungoyot Formation) and more humid/fluvial (Nemegt Formation) facies.

Show MeSH
Related in: MedlinePlus