Table 4.
Stages of gestation (G1–G3) of marsupials at birth by development of external morphology (adapted from Hughes & Hall, 1988; Pask & Renfree, 2010) compared with monotremes at hatching
| Gestation stages | G1 | G2 | G3 | Monotreme hatchling |
|---|---|---|---|---|
| Species |
Eastern quoll
d,k
Tasmanian devil d Striped‐faced Dunnart a Yellow‐footed antechinus i Numbat l |
Virginia opossum
j,k,l
Philander opossum l Common opossum l Grey short‐tailed opossum l,k Monito del monte l Brushtail possum c,l,k Northern brown bandicoot d Southern brown bandicoot g,k |
Tammar wallaby
d
Eastern grey kangaroo d Long‐nosed potoroo e Red‐necked pademelon l Black‐striped wallaby l Common wallaroo l Brush‐tailed rock‐wallaby l Koala l,k Musky rat kangaroo f |
Echidna
b
Platypus b , h |
| Feature | ||||
| Eye primordia | Barely visible | Visible | Prominent | Prominent |
| Eye lids | Not present | Slight/not present | Visible | Not present |
| Retinal pigmentation | Absent/visible | Absent/visible | Prominent ring | Visible |
| Ear primordia | Barely visible | Visible/barely visible | Prominent elevation | Visible |
| Oral shield | Extensive complex | Reduced/simple | Vestigial | Vestigial, mouth open (slit in coronal plane) |
| Definition of mandible | Slight | Moderate | Pronounced | Pronounced |
| Prominence of nasal swelling | Extreme | Extreme/moderate | Slight | Slight |
| Cervical swelling | Present/absent | Absent | Absent | Absent |
| Toes of the hindfoot | Not visible | Visible as folds/formed | Formed | Visible as folds/formed |