Bite marks on an ichthyodectiform fish from Australia: possible evidence of trophic interaction in an Early Cretaceous marine ecosystem

Abstract

Wretman, L. & Kear, B.P., 2013. Bite marks on an ichthyodectiform fish from Australia: possible evidence of trophic interaction in an Early Cretaceous marine ecosystem. Alcheringa 38, 000–000. ISSN 0311-5518.

A well-preserved fish skull from late Albian deposits of the Allaru Mudstone near Richmond in Queensland displays a conspicuous V-shaped pattern of indentations, punctures and depression fractures consistent with a vertebrate bite trace. This is the first direct evidence of trophic interaction between vertebrates within an Early Cretaceous marine ecosystem from Australia. The specimen is taxonomically referable to the large-bodied (ca 1 m snout–tail length) ichthyodectiform Cooyoo australis, but the size and spacing of the tooth marks is incompatible with attack by a conspecific individual. The lack of osseous growths concordant with healing also suggests that the bite occurred shortly before or after the animal’s death. Comparison with the dentitions of other coeval vertebrates indicates compatible tooth arrangements in longirostrine amniote predators such as polycotylid plesiosaurians, ornithocheiroid pterosaurs and especially the ichthyosaurian Platypterygius. The implications of this as a potential predator–prey association are that Early Cretaceous actinopterygians occupied middle-level trophic niches and were in turn consumed by higher-level amniote carnivores, similar to many extant marine vertebrate communities of today.

Lovisa Wretman [[email protected]], Subdepartment of Evolution and Development, Department of Organismal Biology, Uppsala University, Norbyvägen 18A, SE-752 36 Uppsala, Sweden (address for correspondence); Benjamin P. Kear [[email protected]], Palaeobiology Programme, Department of Earth Sciences, Uppsala University, Villavägen 16, SE-752 36 Uppsala, Sweden. Received 8.8.2013, revised 17.9.2013, accepted 23.9.2013.

昆士兰Richmond附近Allaru泥岩Albian 阶地层中的一个保存完好的鱼头骨显示明显的V形压痕、穿孔和压裂纹, 与脊椎动物咬痕迹相一致。这是澳大利亚早白垩世海洋生态系统中脊椎动物之间的营养相互作用的第一个直接证据。该标本在分类学上与大个体(CA 1米吻尾长) ichthyodectiform Cooyoo australis 有关, 但牙痕的大小和间距 与经受同种的个体攻击并不相符。由于愈合而导致的骨增生的缺乏也表明, 噬咬发生在动物死亡前后。与其它同时代的脊椎动物的牙列比较表明, longirostrine脊椎动物的天敌如polycotylid 蛇颈龙、 ornithocheiroid翼龙及特别是鱼龙 Platypterygius的牙齿排列是相同的。作为一个潜在的捕食者 - 猎物者的关系, 此点的意义在于早白垩世actinopterygians占据中层营养生境, 并反过来被更高层的脊椎类食肉动物所捕食, 类似于许多现存的海洋脊椎动物群落。

Key words:

• bone modification
• feeding traces
• stem teleosts
• marine amniotes

Acknowledgments

Thanks to Paul Stumkat (Stumkat Studios, Natural History Art) for assistance with regional museum collections access, field logistics and information. Henning Blom (Uppsala University) commented on earlier drafts of this manuscript. Robert Boessenecker (University of Otago), Michael Everhart (Sternberg Museum of Natural History, Fort Hays State University) and Stephen McLoughlin (Swedish Natural History Museum) also contributed constructive reviews and editorial input. LW acknowledges financial support from the Anna Maria Lundins Stipendiefond; BPK was funded by the Australian Research Council, Swedish Research Council and Sir Mark Mitchell Research Fund.