Scolecophidians or blind snakes are among the most primitive and smaller snakes in the world with an average of size of 10 cm. They are worm-like, fossorial, lucifugous and often colourless, eating ants, termites, and their larvae. Based on the revision of Vidal et al (2010) they are represented by 5 families mainly living in tropical areas and have had a long history on Gondwana. The only European representative of this group is Typhlops vermicularis that lives around the Mediterranean Basin. Here we describe two isolated procoelous trunk vertebrae from the early Paleocene of Hainin (MP1-5, Belgium), a locality already known for the oldest amphisbaenian lizards (Folie et al 2013) and the earliest European scincoid lizards (Folie et al 2005). These vertebrae are clearly attributed to a scolecophian by the following characters (List, 1966): they are 1.5 mm long and 1 mm high and wide; the centrum is narrow and the hemal keel is absent; the orientation of the prezygapophyses processes that serve for muscle attachment strongly differs from the one of the prezygapophyseal facets; the neural arch is depressed and does not present a posterior medial notch nor a neural spine. Fossil scolecophidians are identified based on their vertebrae but they are generally considered as not diagnostic at a familial, generic or specific level. However, some characters have recently been proposed to differentiate the family level on the basis of the shape and placement of the synapophyses, shape of the cotyle, size of the zygosphene, and shape of the prezygopophyseal facets (Gelnaw & Mead, 2010). Based on these features, the Hainin vertebrae differ from those of Anomalepidae and Leptotyphlopidae, and resemble those of Typhlopidae by similar neural arch morphology and height, development and orientation of the paradiapophysis, and morphology of the neural canal, cotyle and condyle. Record of fossil scolecophidians indicates their presence in North America, Europe, Africa and Australia. Before this study, the oldest representatives of this group were known from the late Paleocene of Adrar Mgorn (Ouarzazate Basin) in Morrocco and from the earliest Eocene of Dormaal (Tienen Formation, MP7) in Belgium. The scolecophidian from Hainin resembles more the one from Dormaal than that from Adrar Mgorn by narrower centrum and neural arch. The width of the neural arch in Typhlops is similar to both Belgian scolecophidians, however, the centrum is even narrower. By these characters, the scolecophidian from Hainin could represent a basal Typhlopidae.
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The primary criterion ratified by the International Subcommission on Paleogene Stratigraphy (ISPS) to define the Paleocene-Eocene (P/E) boundary, and the beginning of the Paleocene-Eocene Thermal Maximum (PETM), is the onset of a prominent negative Carbon Isotope Excursion (CIE; Aubry et al., 2007), located in the lower to middle part of Chron C24r, in calcareous nannofossil Zone NP9 and at the base of planktonic foraminiferal Zone E1 of Berggren & Pearson, 2005 (see also Wade et al., 2011), also termed Zone P5 in Aubry et al. (2007). Based on cyclostratigraphy, the CIE is estimated to have spanned 150 ± 20 kyr and would reflect a major perturbation of the global carbon cycle. Organic matter (OM) may be judged as a (very) reliable material for isotopic chemostratigraphy, in both marine and terrestrial settings. Here we show several examples of successions (Belgium, Egypt, France, Spain, Tunisia, USA-Wyoming) where: isotopic analyses on OM are necessary to define the P-E boundary (lack of carbonates and/or diagenetic 1. alteration of the isotopic signal on carbonates, including calcitic shells, bulk rocks and pedogenic nodules), organics are probably not the best material to precise the P-E boundary,2. geological processes, such as hiatuses, and potential reworking of OM in channels and turbidites, may per3. turb the reliability of the carbon isotope results (on both organics and carbonates). Aubry, M.P. et al., 2007. Episodes, 30, 271-286. Berggren, W. A., and Pearson, P. M., 2005, J. of Foraminiferal Research, 35/4, 279–298. Wade, B.S. et al. 2011, Earth Science Reviews 104, 111-142.
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