Anaspids were small marine fish that lacked a heavy bony shield and paired fins, but were distinctively hypocercal. Compared to many other ostracoderms, such as the Heterostraci and Osteostraci, anaspids did not possess a bony shield or armor, hence their name.

无孔亚纲Anapsida又称“缺弓亚纲”，爬行动物纲中的原始类群。 其头骨后部无颞孔。 包括杯龙目 (Cotylosauria)。 龟鳖目 (Chelonia)和中龙目 (Mesosauria)。 杯龙类为爬行动物中最原始的类型，形体粗笨，四肢短粗，颈部不显著。 头骨很少退化，无颞孔。 膜骨性肩带保全完好，匙骨发育。 脊柱神经弧粗大，椎体圆柱形，中为脊索贯穿，还保存有新月形的退化的间椎体。 最早发现于石炭纪，至三迭纪绝灭。 我国山西二迭纪石千峰龙 (Shihtienfenia)和三迭纪新前棱蜥 …

2020年5月29日 · Anaspids. Anaspid fossils are only known from the Silurian period. Their name means "without shields," owning to the fact that they lacked the large head shields that are typical of many ostracoderm groups.

2016年3月16日 · Here we survey the histology of representatives spanning anaspid diversity and infer their generalized skeletal architecture. The anaspid dermal skeleton is composed of odontodes comprising spheritic dentine and enameloid, overlying a basal layer of acellular parallel fibre bone containing an extensive shallow canal network.

The Anaspida, or anaspids, are a group of fossil, jawless vertebrates which lived in the Silurian (-430 to -410 million years ago). Anaspids differ from most other "ostracoderms" by their dermal skeleton not forming a massive headshield, although their head is covered by both large bony plates and minute scales.

Here we survey the histology of representatives spanning anaspid diversity and infer their generalized skeletal architecture. The anaspid dermal skeleton is com-posed of odontodes comprising spheritic dentine and enameloid, overlying a basal layer of acellular parallel fibre bone containing an extensive shallow canal network.

2016年3月16日 · Here we survey the histology of representatives spanning anaspid diversity and infer their generalized skeletal architecture. The anaspid dermal skeleton is composed of odontodes comprising...

The Anaspida are all narrow-bodied jawless vertebrates characterized by triradiate postbranchial spines. They possess rod-like body scales (when not naked), large median dorsal scales or scutes, broad-based paired fins, and a strongly hypocercal (downward- lobed) tail.

Anaspids were a common group of jawless fish in Silurian time. Specimens measure 10 to 15 cm long and have only been discovered in regions that were once part of Euramerica. Unlike other agnathans, whose bodies were often flat, anaspids had a narrower and more slender body, closer to that of a “typical” fish.

2012年5月11日 · Birkeniid anaspids are covered by a series of small plates on the head and rod-shaped scales in a chevron-like pattern on the trunk, which separates them from Lasanius Traquair, 1898, an almost naked anaspid with only several rows of postbranchial spines and median dorsal ridge scales (Blom et al. 2002).