Madtsoiidae

Madtsoiidae is an extinct family of mostly Gondwanan snakes with a fossil record extending from early Cenomanian (Upper Cretaceous) to late Pleistocene strata located in South America, Africa, India, Australia and Southern Europe. Madtsoiidae include very primitive snakes, which like extant boas and pythons would likely dispatch their prey by constriction. Genera include '' Madtsoia'', one of the longest snakes known, at an estimated , and the Australian '' Wonambi'' and '' Yurlunggur''.
As a grouping of basal forms the composition and even the validity of Madtsoiidae is in a state of flux as new pertinent finds are described, with more recent evidence suggesting that it is paraphyletic as previously defined.

Although madtsoiids persisted on Australia until the Pleistocene, they largely went extinct elsewhere during the Eocene. However, some species persisted in South America and India through the Oligocene.

Description

Madtsoiidae was first classified as a subfamily of Boidae, Madtsoiinae, in Hoffstetter (1961). Further study and new finds allowed ranking the group as a distinct family in Linnaean systems. With the recent use of cladistics to unravel phylogeny, various analyses have posited Madtsoiidae as a likely clade within Serpentes, or possible paraphyletic stem group outside Serpentes and within a more inclusive Ophidia.
Madtsoiid snakes ranged in size from less than (estimated total length) to over , and are thought to have been constrictors analogous to modern pythons and boas, but with more primitive jaw structures less highly adapted for swallowing large prey. There are specific anatomical features that diagnose members of this family, such as the presence of hypapophyses only in anterior trunk, that the middle and posterior trunk vertebrae possess a moderately or well-developed haemal keel, except for a few near the cloacal region, often with short laterally paired projections on the posterior part of the keel. Also, all trunk and caudal vertebrae have at least a parazygantral foramen, sometimes several of them, located in a more or less distinct fossa that is lateral to each zygantral facet. Additional features are the prezygapophyseal processes' absence while the paracotylar foramina are present and that the diapophyses are relatively wide, exceeding width across prezygapophyses at least in the posterior trunk vertebrae. (Scanlon 2005)

Like most fossil snakes the majority of madtsoiids are known only from isolated vertebrae, but several (''Madtsoia bai'', ''M. camposi'', ''Wonambi naracoortensis'', ''Nanowana'' spp., unnamed ''Yurlunggur'' spp., ''Najash rionegrina'') have associated or articulated parts of skeletons. Of the genera listed below, all have been referred to Madtsoiidae in all recent classifications except ''Najash rionegrina'', which is included here based on diagnostic vertebral characters described by Apesteguía and Zaher (2006). These authors didn't include Najash among madtsoiids because they consider that madtsoiids are a paraphyletic assemblage of basal macrostomatans related to ''Madtsoia bai'' and consequently, not related to the Cretaceous alethinophidians from southern continents.

Rieppel ''et al.'' (2002) classified ''Wonambi naracoortensis'' within the extant radiation, ( crown group), of snakes as Macrostomata ''incertae sedis'', but many of their character state attributions for this species have been criticised or refuted by Scanlon (2005) and the better-preserved skulls of ''Yurlunggur'' sp./spp. have numerous characters apparently more plesiomorphic than any macrostomatans (Scanlon, 2006). The partial skull attributed to ''Najash rionegrina'' (Apesteguía and Zaher 2006) resembles that of the non-madtsoiid ''Dinilysia patagonica'', and vertebrae support that they are related. The type material of ''Najash'' is the only possible madtsoiid specimen retaining evidence of pelvic and hindlimb elements, which are claimed to be more plesiomorphic than other Cretaceous limbed snakes, such as ''Pachyrhachis'', ''Haasiophis'' or ''Eupodophis'', in retaining a sacro-iliac contact and well-developed limbs, with a huge and well-defined trochanter. The sacro iliac contact is perhaps misleadingly described by Apesteguía and Zaher as unique possession of a sacrum, whereas it has rarely been questioned that the cloacal vertebrae in snakes are homologous to the sacrals of limbed squamates (i.e. the sacrum is present but has lost contact with the reduced ilia in other taxa). It would be unsurprising if other madtsoiids also possessed hindlimbs as complete as those of ''Najash''.

Several madtsoiid genera have been named using indigenous words for legendary Rainbow Serpents or dragons, including ''Wonambi'' (Pitjantjatjara), ''Yurlunggur'' ( Yolngu) and ''Nanowana'' (Ancient Greek ''nano''-, 'dwarf' + Warlpiri ''Wana'') in Australia, and ''Herensugea'' (Basque) in Europe. G.G. Simpson (1933) apparently started this trend by compounding ''Madtsoia'' from indigenous roots. In this particular case these originated from the Tehuelche language, although the reference made was geographic rather than mythological, the derivation being from that language's terms ''mad'', "valley" and ''tsoi'', "cow" as a rough translation from Spanish name of the type locality, Cañadón Vaca.

A 2022 morphological study found Madtsoiidae to be paraphyletic, with '' Sanajeh'' being found to be the most basal member of the Ophidia, whereas the Cenozoic Australian madtsoiids were basal alethinophidians.

Classification

* '' Gigantophis'' Andrews, 1901
** ''Gigantophis garstini'' Andrews, 1901 (Andrews, 1906; Hoffstetter, 1961b; Paleogene, Late Eocene; Egypt ( Birket Qarun and Qasr el-Sagha Formations), Libya)
* '' Madtsoia'' Simpson, 1933
** ''Madtsoia bai'' Simpson, 1933 (Paleogene, Early Eocene Sarmiento Formation; Argentina)
** ''Madtsoia'' cf. ''M. bai'' (Simpson, 1935; Hoffstetter, 1960; Paleogene, Late Paleocene Las Flores Formation; Argentina)
** ''Madtsoia madagascariensis'' Hoffstetter, 1961a (Piveteau, 1933; Cretaceous, Maastrichtian Maevarano Formation; Madagascar)
** ''Madtsoia'' aff. ''madagascariensis'' (de Broin ''et al.'', 1974; Cretaceous, Coniacian or Santonian In Beceten Formation, Niger; Brazil)
** ''Madtsoia pisdurensis'' Mohabey ''et al'', 2011 (Cretaceous, Maastrichtian Lameta Formation; India)
* '' Wonambi'' Smith, 1976
** ''Wonambi naracoortensis'' Smith, 1976 (Scanlon and Lee, 2000; Scanlon, 2005; Neogene, Pliocene

HOME


Content is Copyleft
Website design, code, and AI is Copyrighted (c) 2014-2017 by Stephen Payne


Consider donating to Wikimedia



As an Amazon Associate I earn from qualifying purchases