,1,*, 卢筱洪4, 吴伟强4, 杜衍礼5, 黄志青5, 汪筱林1,3The first Stalicoolithus shifengensis discovered in a clutch from the Sanshui Basin, Guangdong Province
ZHU Xu-Feng1,3, FANG Kai-Yong1,2, WANG Qiang,1,*, LU Xiao-Hong4, WU Wei-Qiang4, DU Yan-Li5, HUANG Zhi-Qing5, WANG Xiao-Lin1,3收稿日期:2017-10-24网络出版日期:2019-01-20
| 基金资助: |
Corresponding authors: *wangqiang@ivpp.ac.cn
Received:2017-10-24Online:2019-01-20
摘要
描述了发现于中国广东省佛山市南海区大沥镇北村水闸施工工地的三水组红层中的首个始丰石笋蛋(Stalicoolithus shifengensis)蛋窝。这一不完整蛋窝保存有3个近完整蛋化石和两个印痕。基于以下宏观形态和蛋壳显微特征,这些蛋可以被归为石笋蛋类的始丰石笋蛋：恐龙蛋呈球形,平均直径为10.5 cm; 蛋壳较厚,平均厚度为3.50 mm, 由柱状消光的壳单元组成,锥体层与柱状层界线不明显;锥体层的厚度为0.25 mm, 约占蛋壳厚度的1/14, 锥体在弦切面下呈花瓣状;柱状层可分为内层、中间层和外层,其中中间层和外层发育大量次生壳单元,气孔道呈蠕虫状。三水组中始丰石笋蛋的发现补充了这一蛋种的蛋窝信息：恐龙蛋在蛋窝中互相叠加,且相互之间间隔一定的距离。同时,这一发现还拓展了这一蛋种的古地理分布,为讨论三水盆地恐龙蛋的多样性奠定了基础。
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Abstract
The first clutch of Stalicoolithus shifengensis is described here. This incomplete dinosaur egg clutch in which three nearly complete eggs and two egg prints were preserved was discovered in the red deposits of the Sanshui Formation at a construction site near the sluice of North Village, Dali Town, Nanhai District, Foshan City, Guangdong Province, China. The eggs in the clutch are stacked with various ranges. Based on the characteristics of the eggshell, these eggs can be assigned to S. shifengensis. The discovery of S. shifengensis in the Sanshui Formation complements the clutch information about the oospecies as well as expands its paleogeographic distribution, and sets the foundation for discussing the diversity of dinosaur eggs in the Sanshui Basin.
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朱旭峰, 方开永, 王强, 卢筱洪, 吴伟强, 杜衍礼, 黄志青, 汪筱林. 广东三水盆地发现首个始丰石笋蛋(Stalicoolithus shifengensis)蛋窝. 古脊椎动物学报[J], 2019, 57(1): 77-83 DOI:10.19615/j.cnki.1000-3118.180110
ZHU Xu-Feng, FANG Kai-Yong, WANG Qiang, LU Xiao-Hong, WU Wei-Qiang, DU Yan-Li, HUANG Zhi-Qing, WANG Xiao-Lin.
1 Introduction
Sanshui Basin is one of the beaded Mesozoic-Cenozoic red basins along the southeastern coast of China. It is located in the northwestern region of the Pearl River Delta, which includes Guangzhou, Foshan, Nanhai and Sanshui, Sihui and Gaoyao, as well as part of Qingyuan and covers an area of approximately 3300 km2 (Hou et al., 2007). The Cretaceous strata in the Sanshui Basin were established based on drilling data, and from bottom to top are divided into the Lower Cretaceous Baihetong Formation, Upper Cretaceous Sanshui Formation and Dalangshan Group (Zhang, 1984).The discovery of the first dinosaur eggs in the Sanshui Basin can be traced back to the 1970s when workers at the Guangzhou Iron and Steel Plant found a clutch of 12 spheroid eggs and two partially preserved elongated eggs in the red deposits located 13 m under-ground (Sun Yat-sen University, 1976). Then in the Pingzhou-Guangzhou Iron and Steel Plant-Fangcun area, two clutches with 27 elongated eggs and a clutch with seven eggs of Paraspheroolithus were found (Sun Yat-sen University, 1976; Zhang and Huang, 1999). According to Zhang et al. (2009) 1)（1) Zhang X Q, Zhang X J, Lin X Y, 2009. New knowledge of vertebrate fossils in Sanshui Basin. Paper presented at the 10th national congress of Palaeontological Society of China (PSC) & the 25th annual conference of PSC. Nanjing.）, dino-saur eggs were found within the red deposits of the Cretaceous Sanshui Formation at a construction site in Datang Industrial Park, Sanshui District, as well as at Sanshui Second Bridge, Beijiang Dike, and on the west side of the Hekou Geological Team Base. Egg clutches composed of elongated and spheroid eggs were found in several places in Shijiao Town, Qingyuan (Fig. 1).
Fig. 1
新窗口打开|下载原图ZIP|生成PPTFig. 1The distribution of dinosaur egg sites in the Sanshui Basin
Basin boundary modified from Zhang et al., 2008; stratum distribution according to 1:200000 geological map, F4912, online data. 1. Zhong Village; 2. Meihua Village; 3. Jixiang Road; 4. Baihedong; 5. Pingzhou; 6. North Village; 7. Shijiao Town; 8. Datang Industrial Park; 9. Beijiang Dike; 10. Sanshui Second Bridge; 11. Hekou Geological Team Base
The records of dinosaur eggs in Sanshui Basin are concentrated in two areas: from Sanshui to Qingyuan in the northwestern part of the basin, and from Foshan to Guangzhou in the eastern part of the basin (Fig. 1). Zhang and Huang (1999) pointed out that in the Sanshui Basin the lower layer bearing spheroid eggs belongs to the first member of the Baihedong Group (or Baihedong Formation), and the middle layer bearing spheroid and elongated eggs belongs to the first member of the Sanshui Formation. Considering the facts mentioned above, we believe that the dinosaur egg-bearing red deposits this paper discusses should be classified as part of the Sanshui Formation.
2 Systematic paleontology
Stalicoolithidae Wang et al., 2012Stalicoolithus Wang et al., 2012
Stalicoolithus shifengensis Wang et al., 2012
Described specimen B 2017-1, an incomplete clutch (Fig. 2). The specimen is part of the collection at the Nanhai Museum.
Locality and horizon North Village, Dali Town, Nanhai District, Foshan City, Guangdong Province; Upper Cretaceous, Sanshui Formation.
Diagnosis Eggs are stacked in the clutch and are spheroids with an average diameter of 10.5 cm on average. The eggshell is 3.50 mm thick on average, and is constructed of eggshell units that show columnar extinction under cross-polarized light. The boundary between the cone layer and the columnar layer is not distinct. The columnar layer can be divided into inner, medial and outer zones. The secondary eggshell units are well developed in the medial and outer zones of the columnar layer. The pore canals are wormlike.
Fig. 2
新窗口打开|下载原图ZIP|生成PPTFig. 2The clutch of Stalicoolithus shifengensis B 2017-1 from the Sanshui Basin
A. incomplete clutch composed of five dinosaur eggs of Stalicoolithus shifengensis in top view, No. 1, 2, 3 are near complete eggs while No. 4, 5 are only egg prints; B. the clutch in lateral view showing the arrangement of the eggs in a different horizontal plane; C, D. magnification figures of No. 2 (C) and No. 3 (D)
Description An incomplete clutch with at least five eggs comprising three nearly complete eggs and two egg prints stacked in the clutch with various ranges (Fig. 2). The eggs are spheroids with an average diameter of 10.5 cm. The average thickness of the eggshell is 3.50 mm. The eggshell is constructed out of closely arranged eggshell units, which show columnar extinction under cross-polarized light (Fig. 3A, B). The boundary between the cone layer and the columnar layer is not obvious. The cone layer is 0.25 mm thick on average, which is approximately 1/14 of the eggshell thickness. The cone is flower-like, and the cone gaps are significant (Fig. 3C, D). The columnar layer is 3.25 mm thick on average and it can be divided into three zones (Fig. 3A): the average thickness of the inner zone of the columnar layer is 1.25 mm (about 5/14 of the eggshell thickness) and displays obvious horizontal accretion lines; the medial zone of the columnar layer is 1.25 mm thick on average (about 5/14 of the eggshell thickness) and is characterized by bright strips; the outer zone of the columnar layer is composed of loosely arranged eggshell units, it is 0.75 mm thick on average (about 3/14 of the eggshell thickness) and is characterized by a large number of multilayer stacked secondary eggshell units (Fig. 3E, F). The pore canals are wormlike in radial section (Fig. 3A), round or oval in the tangential view of the medial zone of the columnar layer with an uneven distribution (Fig. 3G, H), and are irregular in the tangential view of the outer zone of the columnar layer (Fig. 3F).
Fig. 3
新窗口打开|下载原图ZIP|生成PPTFig. 3Microstructure of Stalicoolithus shifengensis B 2017-1 from the Sanshui Basin
A. radial section of eggshell, showing the boundaries of the cone layer, the inner zone of the columnar layer, the medial zone of the columnar layer and the outer zone of the columnar layer; B. radial section of eggshell (under cross-polarized light); C. radial section through the cone layer, white arrows indicate the position of organic core; D. tangential view of the cone layer, white arrow indicates the position of the organic core; E. radial section through the outer zone of the columnar layer showing the secondary eggshell units arranged in multiple layers; F. tangential view of the outer zone of the columnar layer showing the secondary eggshell units in irregular shaped pores; G-H. tangential views of the medial zone of the columnar layer showing the round and oval pores and their distribution
The macrostructure and microstructure of the dinosaur eggs found in Foshan can be compared to Stalicoolithus shifengensis from the first member of the Chichengshan Formation, Upper Cretaceous, Tiantai Basin, Zhejiang. The holotype of S. shifengensis found in Tiantai Basin is a single egg (Wang et al., 2012). Although the clutch found in Foshan is incomplete, we can still obtain some of the clutch’s information of S. shifengensis. The dinosaur eggs are stacked in the egg clutch without obvious arrangement and spaced apart from each other.
Liu et al. (2016) reported a clutch of dinosaur eggs found in Pingshan, Shenzhen in 2013 and identified them as Pinnatoolithus. However, Pinnatoolithus is a synonym for Ovaloolithus (Zhao et al., 2015). The misclassification happened when Liu et al. (2016) compared microscopic photographs of a radial section of her eggshells with those of Fang’s Pinnatoolithus (2009) and she did not notice that their specimens were placed in opposite directions (see Liu et al., 2016:fig. 4A-D; Fang et al., 2009:figs. 3-5). Here, we suggest that it should be standard practice to arrange photographs of radial sections of eggshells with the outer surface on top to avoid such mistakes. The previously described columnar layer is actually the medial and outer zone of the columnar layer of a typical Stalicoolithidae, and the described mammillary layer (or cone layer), which is on average half the thickness of the eggshell, is the equivalent of the inner zone of the columnar layer and the cone layer of the Stalicoolithidae. Histostructural differences between the eggs of the Stalicoolithidae and the eggs we describe here are scarce. Prior to further observation, we advise that the specimen mentioned by Liu et al. (2016) should be identified as a member of the Stalicoolithidae.
3 The age of dinosaur egg-bearing red deposits in the Sanshui Basin
There are different understandings of the age of dinosaur egg-bearing red deposits in the Sanshui Basin. Based on paleomagnetic data, Yuan and Wang (1992) argued that the age of the Baihedong Group is 128-93 Ma, which ranges from the middle and late stages of the Early Cretaceous to the early stages of the Late Cretaceous , and that the age of the first member of Sanshui Formation is 93-83 Ma, which belongs to the early and middle stages of the Late Cretaceous. Zhang and Huang (1999) agreed with this view in their summary of dinosaur egg-bearing layers and their distribution in Guangdong. According to the division of ostracods, the Sanshui Group can be compared with the Nanxiong Group, which belongs to the early and middle stages of the Late Cretaceous (Zhang et al., 2008). The age of the Chichengshan Formation in the Tiantai Basin is about 94-91 Ma (He et al., 2013) and belongs to the early stages of the Late Cretaceous similarly to that of the Sanshui Formation.4 Paleogeographic distribution of Stalicoolithus shifengensis
The Stalicoolithus shifengensis in Foshan, Guangdong represents the first discovery of this oospecies outside its type locality the Tiantai Basin, Zhejiang Province, which provides new paleontological material for the classification and comparison of the Late Cretaceous continental red deposits in the Sanshui Basin and enriches the paleogeographic distribution of the Stalicoolithidae. In addition, this study is the first detailed description of the discovery of dinosaur eggs in the Sanshui Basin and therefore will lay a foundation for exploring the diversity of dinosaur eggs in the Sanshui Basin.Acknowledgments
The authors would like to thank Zhang Jiang-Yong from the IVPP for field information. Thank Qiu Li-Cheng from Guangdong Provincial Institute of Cultural Relics and Archaeology, Wu Zhen-Yu, Luo Hui-Zhen from the Nanhai Museum, and Zheng Ying-Qing from the Cultural Station of Dali Town who provided help during the fieldwork. We thank our reviewers for going over the manuscript and their valuable suggestions. The research was funded by the National Natural Science Foundation of China (41672012, 41688103, 41572020).参考文献 原文顺序
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DOIURL [本文引用: 1]
Dinosaur eggs or fragments are abundant and extensively distributed in China. They can be very informative in biostratigraphic division and correlation of continental strata where other fossils are relatively lacking. Despite remarkable discoveries of vertebrate fossils, particularly dinosaur eggs and skeletons from the middle and Late Cretaceous of both northern and southern China, there is hardly any direct evidence for the ages of the vertebrate-bearing terrestrial deposits. To constrain their depositional ages, here we have obtained SIMS U-Pb zircon ages from the tuffs interbedded with dinosaur egg-bearing sediments from the Laijia and Chichengshan formations of the terrestrial red deposits of the Late Cretaceous in the Tiantai Basin, Zhejiang Province, southeastern China. The SIMS zircon U-Pb ages from the Laijia and Chichengshan formations are about 96-99 Ma (Cenomanian) and 91-94 Ma (Turonian), respectively, providing direct time constraints on the vertebrate and dinosaur egg evolution in the Late Cretaceous as well as a basis for correlation with terrestrial Cretaceous deposits in other regions of southern and northern China. (C) 2012 Elsevier Ltd.
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