This species probably lived near a freshwater lake, and probably hunted for other small creatures that lived in the same habitat. It was a slender animal, with rather small legs and a long tail. Together with
Casineria, another
transitional fossil found in
Scotland, it is one of the smallest reptile-like amphibians known, being a mere 20 cm in adult length. The small size has made it a key fossil in the search for the earliest
amniote, as amniote eggs are thought to have evolved in very small animals. It shares many features with reptiles and other early amniotes rather than most amphibious tetrapods of its age. These include a lower number of ankle bones, no labyrinthodont infolding of the
dentin, the lack of an
otic notch, and a generally small skull. Many of these features are also present in lepospondyls. Ruta et al. (2003) interpreted the long body and small legs as a possible adaption to burrowing, similar to that seen in modern
skinks. Members of
Westlothiana were heavily scaled, with thin scales on the belly and many rows of thick, overlapping scales on the back. In more basal reptiliomorphs, this issue did not occur because an additional bone known as an intertemporal was present at the intersection of the four bones. Most reptiliomorphs which lost the intertemporal filled the space using a 'lappet' of the parietal bones. However, in
Westlothiana, Limnoscelis, and lepospondyls, this space is filled by an expansion of the rear branch of the postorbital bone. Practically all other reptiliomorphs possessed five-fingered hands, except for the majority of lepospondyls. Lepospondyls (with the exception of
Diceratosaurus and
Urocordylus) possessed four or fewer fingers. Analyses which consider
Westlothiana to possess only four fingers generally agree that it is a lepospondyl. In basal amniotes, the condition is quite different, with the ankle only formed by eight bones. The five distal tarsals are typically unchanged, but usually only a single centrale is preserved. This single remaining centrale, referred to as the "
navicular" bone, was either formed by the retention of only the second centrale or the fusion of the first and second. Amniotes are also very different from amphibians in the fact that they possess only two large proximal tarsals. The
calcaneum, which contacts the fibula, is almost unanimously considered to be identical to the fibulare. The other proximal tarsal, the
astragalus (or talus), is likely a mass formed by the fusion of the intermedium, tibiale, and the fourth (and possible also the third) centrale. Some lepospondyls, such as the reptile-like
microsaur Tuditanus, also may have evolved these modifications. The ankle of
Westlothiana, as well as that of most other "reptiliomorphs", is intermediate between these two conditions. Smithson (1989) reported that "Lizzie" had nine ankle bones, including an astragalus and calcaneum, and that the third and fourth centrales were already fused or lost. Yet he also noted that centrales one and two (which formed the navicular bone) were unfused. Smithson et al. (1993) later claimed that there were ten bones, arguing that the components of the astragalus were not completely fused, with the intermedium and tibiale still separate. Piñeiro, Demarco, & Meneghel (2016) could not determine which of these two interpretations were superior, but did note that the largest bone more closely resembled a fused astragalus rather than an unfused intermedium. The foot was most likely five-toed, with a phalangeal formula (the number of
phalanges per toe from the innermost to outermost toe) of 2-3-4-5-4. This formula is identical to that of early amniotes, but conversely the foot of
Westlothiana is shorter and more robust than the long-toed feet of amniotes. Additionally, the phalanges decrease in relative size towards the tip of the foot in this genus, while the opposite is true of amniotes. ==Phylogeny==