Undulatoolithus pengi
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publication ID |
https://doi.org/ 10.11646/zootaxa.3746.1.9 |
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publication LSID |
lsid:zoobank.org:pub:E6F80E2A-D60B-43B7-97CF-C2A7D2C1B327 |
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persistent identifier |
https://treatment.plazi.org/id/D77A9E56-FFDC-FFAD-FF1C-FE2BCF93643F |
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treatment provided by |
Felipe |
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scientific name |
Undulatoolithus pengi |
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Undulatoolithus pengi oogen. et oosp. nov.
Holotype: A clutch with 5 more or less well preserved eggs and 3 broken eggs (PXMV-0016) ( Fig. 2 View FIGURE 2 ), housed in the Pingxiang Museum , Jiangxi Province.
Locality and horizon: Changxi ( Fig. 1 View FIGURE 1 ), Pingxiang City; Zhoutian Formation, Upper Cretaceous.
Etymology: The oospecific epithet honors the late Peng Anbao, chief curator of the Pingxiang Museum, who collected and protected the dinosaur eggs from the Pingxiang Basin.
Diagnosis: Elongated egg type with a polar axis length of about 19.36 cm and equatorial diameter of 8.35 cm, giving a shape index is 43.1. The outer surface of the eggshell is sculptured with nodes and longitudinally aligned ridges, and the ridges is 0.67 mm in height, about half of the entire eggshell thickness. The eggshell thickness is 0.78mm (excluding ornamentation) or 1.46 mm (including ornamentation). Cone layer is thin, 1/8 or 1/4 of eggshell thickness. There is gradational boundary between cone layer and columnar layer.
Description: All the eggs are paired, and arranged in a circular configuration with the central part about 10 cm in diameter ( Fig. 2A View FIGURE 2 ). The angle between pairs is 45.5–107 degrees ( Fig. 2B View FIGURE 2 ). The eggs are slightly asymmetrical and elongate, with average polar axis length and equatorial diameter of 19.36 cm and 8.35 cm, respectively ( Table 1). They are positioned with the blunt pole toward the centre of the nest and the narrow pole directing outwards.
The outer surface of the eggshell is sculptured, with the ornamentation pattern consisting of distinct nodes and short ridges that look like nodes coalesced. Both poles are always ornamented with irregularly shaped nodes ( Fig. 3A View FIGURE 3 ). These ridges are parallel to one another or bifurcate in the equatorial part ( Fig. 3B, C View FIGURE 3 ), and from 2.00 mm to 5.81 mm long. The flat interspaces between the ridges are 0.23-0.71 mm wide.
The eggshell thickness ranges from 0.78 mm (measured from the level of the cone apices to the valley between ridges) to 1.46 mm (measured including the ridges). The ridges have a height of 0.67 mm, about half of the total eggshell thickness ( Fig. 4A, B View FIGURE 4 ).
The eggshell consists of the cone layer and the columnar layer. The contact between the cone layer and the overlying columnar layer is gradational ( Fig. 4A, B View FIGURE 4 ). The cones are conical and closely packed ( Fig. 4A, C, D View FIGURE 4 ). As part of cones eroded, so the cone layer is not complete and thinner than the actual thickness, especially they are little organic cores can be seen in the eggshell radial section ( Fig. 4A, C View FIGURE 4 ). The thickness of the cone layer is approaching 0.15 mm, and the thickness of the columnar layer is 0.62mm (excluding ornamentation) or 1.29 mm (including ornamentation), respectively. Thickness ratio of the two layers is 1/8 or 1/4.
The growth (accretion) lines undulate along with the outer sculptured surface, especially in the upper part of the columnar layer ( Fig. 4A, B View FIGURE 4 ). Oval to elliptical pores penetrating the columnar layer are visible in tangential sections ( Fig. 4D View FIGURE 4 ), with the pore diameter ranging from 0.14-0.18 mm.
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.