SENI biometric analysisextinct Scincidae Genus Macroscincus

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Brian - LCRC
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SENI biometric analysisextinct Scincidae Genus Macroscincus

Post by Brian - LCRC » Sat Aug 26, 2006 1:24 pm

Leeway Corucia Research Center (LCRC)

Courtesy of POLYPHEMOS (2004)

SENI Biometric Analysis on the Extinct Scincidae species: Macroscincus coctei (underlined)

It has been determined that through mitochrondrial DNA research

that Macroscincus coctei has been linked to the Mabuya genus and may

both belong to the same clade. Evidence suggests that due to rafting

episodes, Mabuya species occupied the Cape Verde archipelago from

West Africa. By the Pleistocene, Macroscincus coctei had occupied the

northwestern group of islands and in a case of parallelism, Mabuya

villianti occupied the southern group of Cape Verde islands (Carrenza et

al.,2001). Both were large Scincids of a somewhat herbivorous nature

(based on dentition).

The Cape Verde Islands were denuded some five hundred years ago with

importation of domestic animals.

Working with an extant living relative, Mabuya striata sparsa, many

common features were noted. On this work submitted both

Macroscincus coctei and Mabuya striata sparsa had a SENI value of .13 ;

indicating a similar low canopy arboreal niche.


Macroscincus coctei, a giant member of the Scincidae, became

extinct before a proper study of it's lifestyle could be conducted.

The few scientific studies of this species that were done were made

after the ecosystem was vastly altered.

Using a designed biometric ratio, extant members of the

Scincidae were tested. A systematic numerical linkage of a given species

to a known ecological niche resulted. The technique was then utilized with

Macroscincus coctei to determine it's ecological niche.

The SENI is a ratio based on anterior foot length at the junction of the

ulna/radius-carpal bones to the longest digit divided by the snout to vent

length {SVL} (B. Schnirel, 2003). It had been determined that a

relationship seemed to exist between the length of certain body

proportions such as the anterior foot length and type of environment

common to a given Scincidae species. The more arboreal a skink

species, the larger the proportion. The SENI method can be a

useful in confirming the environmental niche, and possibly determining

the trophic level of extinct skink species unavailable for direct study.

Species (Extant) known Ecological Niche Seni
Scientific Name/
Common Name

Chalcides chalcides Subterranean .01
North African Worm Skink ( Deep-Burrower)

Chalcides sepsoides Subterranean .02
North African Ribbon Skink (Shallow-Burrower)

Eumeces scheideri Fossorial .06
Berber Skink

Tiliqua gigas Fossorial .06
New Guinea Blue-Tongue Skink

Hemisphaeriodon gerrardi Semi-Arboreal .11
Pink-Tongue Skink

Kabuya striata sparsa Arboreal .13
Kalahari Black Tree Skink (Low-Canopy)

Corucia zebrata zebrata Arboreal .17
Common Monkey Skink (High-Canopy)

Macroscincus coctei .13
Cape Verde Giant skink


The SENI biometric ratio has given a good numerical perspective of the differences

between Scincidae species in their lifestyle as well as appearance.

Since the initial development of the SENI biometric ratio in 2003 and the intial study

of the species described in this paper, the Leeway Corucia Research Center has

used this method extensively and it has given insight into our research with

the extant species: Corucia zebrata. In addition to C/A biometric ratio studies and

comparisons of SVL and LOA measurements, the SENI formula is one more tool for

comparison of Corucia zebrata with Macroscincus coctei and other members of the



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