International researchers including scientists from Nanjing Institute of Geology and Palaeontology (China) have found a tapeworm fossil preserved in amber. The amber was mined in Myanmar and is believed to date from approximately 99 million years ago. The three-dimensionally preserved fossil displays unique external and internal features. These features most closely resemble the tentacles of the trypanorhynch tapeworms that parasitise marine elasmobranchs (sharks and rays).
It is a mystery as to how the marine parasite ended up preserved in tree resin. One theory is that the carcase of an elasmobranch was scavenged by a theropod dinosaur. The dinosaur fed on the carcase close to where a pine tree was exuding resin. As the dinosaur tore the carcase apart part of the parasite was flung at the tree and entombed in the resin as it seeped from the bark.
A hypothetical ecological reconstruction of the fossil trypanorhynch tapeworm (drawn by YANG Dinghua). The fossil tapeworm was lodged in the intestine of an elasmobranch and the dead host was possibly scavenged by a dinosaur on a strandline with pine resin extruding nearby. Picture credit: Cihang Luo.
Studying a Tapeworm Fossil
Tapeworms are a type of parasitic flatworm (Class Cestoda). Many have complex life cycles, with larvae developing in one host before invading a secondary host in which they grow to adults and produce eggs. Some six thousand species are known, and they infect all major groups of vertebrates including mammals and ourselves. Their fossil record is extremely sparse. However, there is a record of possible tapeworm eggs having been preserved in the coprolite of a Permian shark.
Researcher Wang Bo (Nanjing Institute of Geology and Palaeontology), commented that the fossil is the first ever tapeworm body fossil found. The specimen provides direct evidence of the evolution of the Cestoda.
The fossil tapeworm from mid-Cretaceous Kachin amber (circa 99 million years ago) and the comparison with the tentacle of an extant trypanorhynch tapeworm. (A) Microscopic image of fossil tapeworm. (B) Micro-CT image of fossil tapeworm. (C) Scanning electron microscopy image of an extant trypanorhynch tapeworm. Picture credit: Cihang Luo.
The discovery demonstrates the remarkable preservation properties of amber.
How Did the Marine Tapeworm Become Trapped in Tree Resin?
PhD student Luo Cihang (Nanjing Institute of Geology and Palaeontology), suggested how a marine tapeworm became trapped in tree resin.
He proposed:
“It may have parasitised the intestines of a ray. The ray’s body was washed ashore and was preyed upon by a dinosaur. As the dinosaur consumed the internal organs of the ray, the worm fell out and become enveloped in nearby resin.”
The research, conducted by scientists from multiple countries including China, Germany, the United Kingdom and Myanmar, was recently published in the academic journal Geology.
The comparison of the internal structure of the fossil (A) with the tentacle of an extant trypanorhynch tapeworm (B). Abbreviation: ivt—invaginated tentacle. Picture credit: Cihang Luo.
A Remarkable Fossil Find
A spokesperson from Everything Dinosaur commented that this was a remarkable and unique fossil discovery. To find a tapeworm fossil preserved in amber is astonishing. Furthermore, it added to the growing body of evidence that amber from Myanmar was produced from Cretaceous trees growing close to the coast. Amber from Myanmar has yielded some amazing fossils, including the shell of an ammonite. The ammonite shell preserved in the tree resin is further evidence that this Cretaceous forest was close to a marine environment.
To read Everything Dinosaur’s early blog post about the ammonite shell preserved in amber: Ammonite Shell Preserved in Amber from Myanmar.
The scientists conclude that the exquisite preservation provides and exceptional example of a marine endoparasite. The study provides, arguably the most convincing body fossil of a flatworm discovered to date.
Everything Dinosaur acknowledges the assistance of a media release requested from the Chinese Academy of Sciences in the compilation of this article.
The scientific paper: “Exceptional preservation of a marine tapeworm tentacle in Cretaceous amber” by Cihang Luo, Harry W. Palm, Yuhui Zhuang, Edmund A. Jarzembowski, Thet Tin Nyunt and Bo Wang published in Geology.
The Everything Dinosaur website: Prehistoric Animal Models and Fossil Replicas.
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