Havesson Y I, Schmidt G A
Gegenbaurs Morphol Jahrb. 1978;124(5):680-84.
Anatomical features of the Tylopoda are determined to a great extent by the convergence with the Ruminantia. The dental system adapted to the double mastification of plant food. The convergent character of the structure of limbs follows from the reduction of carpal and tarsal bones in the Tylopoda and their presence in the Ruminantia. The Ruminantia have no mandibular angular processes which are present in the Tylopoda. In the Tylopoda, the foramina in the transversal processes of cervical vertebrae from a canal by which the vertebral artery opens in the brain. In the Ruminanta there is no such a canal. The embryonic development of camels is characterized by the promitive features of provisory organs. The mating of camels occurs in winter, a feature probably showing that they have preserved the reproduction cycle of the Southern Hemisphere animals.
胼足亚目的解剖特征在很大程度上是由与反刍亚目的趋同演化所决定的。其牙齿系统适应于对植物性食物的双重咀嚼。四肢结构的趋同特征源于胼足亚目腕骨和跗骨的减少以及反刍亚目这些骨骼的存在。反刍亚目没有胼足亚目所具有的下颌角突。在胼足亚目中，颈椎横突上的孔形成一条管道，椎动脉通过该管道进入脑部。而反刍亚目中不存在这样的管道。骆驼的胚胎发育具有临时器官的原始特征。骆驼在冬季交配，这一特征可能表明它们保留了南半球动物的繁殖周期。
