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Young
：基因组证据：树鼩是一种更接近灵长类的哺乳动物
7
续表
1
Continuing table 1
内容
Context
共享的相似性
Shared similarities
颅后形态
Postcranial morphology
四肢和指头高运动性
Limbs and digits highly mobile
前后肢均有
5
趾
Numerous details of limb musculature
前肢骨和后肢骨相似
Osteological similarities in both forelimbs and hindlimbs
手心和脚底有脊状皮肤
Ridged skin on palms and soles
大脑及感官器官
Brain and sense organs
嗅觉器官退化
Olfactory apparatus reduced
发达的视觉器官
Visual apparatus enhanced
视网膜中央无血管
Central, avascular area of retina
大脑皮质延伸，头颅尺寸增大
Neocortex expanded; brain size increased
有距状沟
Calcarine sulcus present
生殖生物学
Reproductive biology
阴茎为悬垂式，阴茎位于阴囊前
Penis pendulous; testes scrotal
与眼镜猴及猿类相似，胎盘呈圆形状
Discoidal placenta, as in tarsiers and simians
每胎约
2-6
只
Small litter size; small number of teats
其他特征
Miscellaneous
有盲肠
Caecum present
分子亲和力
(
如
:
白蛋白
)
Molecular affinities (e.g. albumins)
表
2
表中列举一些存在灵长类动物，在树鼩中却不存在的特征，来自
Martin (1990)
Table 2 This table shows some features that are shared amongst extant primates but are absent in tree-shrews. Adapted from Martin (1990)
特征
Feature
灵长类
Primate condition
树鼩
Tree-shrew condition
手和脚
Hands and feet
适于抓握
Prehensile
不善于抓握
Not prehensile
大脑
Brain
有外侧沟和距状沟
Lateral and calcarine sulcus present
缺少外侧沟和距状沟
Lateral and calcarine sulcus absent
阴囊
Scrotum
位于阴茎后位
Postpenial
位于阴茎前位
Prepenial
下切牙
Lower incisors
下颚的每一边有两个或者更少
Two or less on each side of the lower jaw
下颚的每一边有三个
Three on each side of the lower jaw
上切牙
Upper incisors
横向排列
*
Arranged transversely *
纵向排列
Arranged longitudinally
出生的后代
Offspring at birth
早熟
Precocial
晚熟
Altricial
妊娠期
Gestation period
与体型相比，相对较长
Relatively long compared to body size
与体型相比，相对较短
Relatively short compared to body size
注
: *
许多古老的灵长类拥有纵向排列的上切齿
(
如
:
更猴
(Plesiadapis tricuspidens))
Note: * Many archaic primates have longitudinally arranged upper incisors (e.g. Plesiadapis tricuspidens)