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The Palaeoscolecida and the evolution of the Ecdysozoaстатья
- Авторы: Zhuravlev A.Yu, Gámez Vintaned J.A., Liñán E.
- Журнал: Palaeontographica Canadiana
- Том: 31
- Год издания: 2011
- Первая страница: 177
- Последняя страница: 204
- Аннотация: Palaeoscolecidans are a key group for understanding the ear- ly evolution of the Ecdysozoa. The Palaeoscolecida possess a terminal mouth and an anus, an invertible proboscis with pointed scalids, a thick integument of diverse plates, sensory papillae and caudal hooks. These are features that draw a secret out of these worms, indicating palaeoscolecidan af- finities with the phylum Cephalorhyncha, which embraces priapulids, kinorhynchs, loriciferans and nematomorphs. At the same time, the Palaeoscolecida share a number of char- acters with the lobopod-bearing Cambrian ecdysozoans, the Xenusia. Xenusians commonly possess a terminal mouth, a proboscis (although not retractable), and a thick integu- ment of diverse plates. However, they also have telescopic lobopods similar to those of the Onychophora and the Tar- digrada. It seems likely that cephalorhynchs are descendents of xenusians, which lost walking appendages and acquired a retractable proboscis as well as a vermifom body during adaptation for a burrowing lifestyle. The cephalorhynchs could have evolved from limb-bearing xenusian-like ec- dysozoans via intermediate forms like the semi-burrowing Facivermis, with lobopods surrounding a terminal mouth and a slim vermiform abdomen, and not vice versa. Tardi- grads, onychophorans and anomalocaridids may represent other xenusian offsprings developed through morphological and behavioural evolution for interstitial, surface-dwelling and swimming lifestyles, respectively. This great variety of Cambrian transitional forms corresponds well with the Ec- dysozoa concept, whereas no such forms are found to sup- port the Articulata hypothesis.
- Добавил в систему: Журавлев Андрей Юрьевич
Прикрепленные файлы
| № | Имя | Описание | Имя файла | Размер | Добавлен |
|---|---|---|---|---|---|
| 1. | Полный текст | Zhuravlev_Gamez_Vintaned_Linan_2011_Ecdysozoa.pdf | 5,9 МБ | 24 октября 2014 [AYZhuravlev] |