Searching in 100 million-year-old amber reveals mating of ostracodes

Study ostracods from Myanmar amber. Sincerely: NIGPAS

Small bipolar crustacean ostracods are the most abundant fossil arthropod since Ordovian and play an important role in paleoniviral reconstruction and evolutionary biology.

The vast majority of fossil ostracods are represented by calcified shells, and their soft parts, which can provide invaluable information about ancient Ostrade autocology, are extremely rare.

Recently Dr. of Nanjing Institute of Geology and Palaeontology of the Chinese Academy of Sciences (NIGPAS). Wang He and Pro. Wang Bo and his colleagues presented exceptionally well-preserved ostracodes with medial to soft parts (appendages and reproductive organs). – Ceresius Myanmar amber (~ 100 million years old), which detected mating of Ostracod.

The study was published in Proceedings of the Royal Society B On 15 September.

The Ostracode assemblage in amber is composed of 39 individuals in one amber fragment and includes males, females, and juveniles.

X-ray micro-computed tomography was used to obtain high-resolution three-dimensional images of their soft parts. Micro-CT reconstructions provided direct evidence of giant sperm containing the male clasper, sperm pump (genker organs), hemipenes, eggs, and female sperm.

Mating of 100 million year old amber ostracodes revealed

Preserved body parts in fossils compared to modern analogs. Sincerely: NIGPAS

This is the first time that the giant Ostracod sperm has been found in the Cretaceous ostracod fossil; Its length was at least one-third ostracode by body length. The discovery is also the earliest known animal sperm record, and is approximately 50 million years older than the previous oldest fossil record for animal sperm.

Analysis of fossilized and extinct oestrodods suggests that during sexual reproduction, the male used his fifth-sex deformed organ, which contains hook-like endopods, which allow a woman to attach her hemipes to the woman’s paired vagina. Grips while presenting. The male pair of zenker organs transfer extraordinarily long but immature sperm through the male hemipenes into the female.

Zenker’s organ is easily identified as part of a large, shiny, covered sperm in the extinct cipridoidine ostracodes. Muscle fibers connect several spinal nerves with limbs, often arranged at multiple levels, with a taxa-like characteristic at the family level.

Once in the female, the sperm is pushed into two long sperm canals, each of which culminates in a sacral seminal reception for sperm storage; There, they eventually become motive, arranging themselves in a more organized combination and fertilizing the eggs during the process of ovulation.

Mating of 100 million year old amber ostracodes revealed

Artist reconstruction of fellow orgasm. Sincerely: Young Dinghua

Research shows that the performance of reproductive behavior in the ostracod, which is associated with considerable morphological adaptation, has remained unchanged for at least 100 million years – a paramount example of evolutionary stagnation.

The presence of a complex reproductive system involving giant sperm improved mating success and may have been an important contributor to the late Mesozoic eruptive radiation of the superfamily Cypridoid, which today includes the majority of non-submarine outbreak species.

Ancient giant sperm was discovered on Riversleigh World Heritage Fossil Site

more information:
Extraordinary preservation of reproductive organs and giant sperm in cretaceous ostracods, Proceedings of the Royal Society B (2020). rspb.royalsocietypublishing.or… .1098 / r oxid.2020.1661

Provided by Chinese Academy of Sciences

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