Left: snake vertebral column showing the four main regions (plus atlas and axis). Drawing modi fi ed from Szyndlar (1984). Right: the four basic types of vertebrae of the snake vertebral column: A, cervical vertebra in cranial (A1) and left lateral (A2) views; B, trunk vertebra in cranial (B1) and left lateral (B2) views; C, cloacal vertebra in cranial view; D, caudal vertebra in cranial view. Abbreviations: HE, hemapophyses; HK, haemal keel; HY, hypapohysis; LY, lymphapophyses; PLE, pleurapophyses. Not to scale. 

Contexts in source publication

Context 1

... work intends to partially fi ll this gap on the knowledge of Miocene ophidians from Catalonia on the basis of recently recovered Late Aragonian material from the area of els Hostalets de Pierola (Vallès-Penedès Basin, Catalonia, Spain). In particular, the fossil remains reported here were recovered during the works of paleontolo- gical control and excavation carried out in the Abocador de Can Mata (ACM; see Alba et al., 2006a,b, 2007, 2009). To date, more than 43,000 large vertebrate remains and several thousands of microvertebrate remains have been recovered (Alba et al., 2009). Among others, this has led to the recovery of several ophidian vertebrae, although in many instances the fragmentary preservation precludes an accurate taxonomic attribution. In this work, we report the preliminary taxonomic attribution of the ophidian vertebral remains from the local series of ACM that have been thus far prepared for study. The sediments exposed on the ACM local stratigraphic series are mainly composed by clayish levels, sometimes with sandstone and conglomeratic levels intercalated. The clay levels are usually reddish to gold-yellowish co- loured, with a metric to decametric thickness. Nodules, pedogenic processes, bioturbation and decoloured marks are more or less common on this beds. These deposits are interpreted to have originated in alluvial-fan marginal to distal environments, with a fl uctuating radius span and transport ef fi ciency (Casanovas-Vilar et al., 2008). The series is about 300 m-thick and includes more than 150 fossil vertebrate localities (Alba et al., 2009), which can be accurately dated on the basis of lito-, bio- and mag- netostratigraphic data (Moyà-Solà et al., 2009). The series approximately ranges from 12.5 to 11.3 Ma, mainly corresponding to the MN 7 and MN 8 biozones (sensu Mein and Ginsburg, 2002: Late Aragonian, middle Miocene). The material described in this work comes from a total of six different localities, with the following estima- ted age: C2-B3 and C3-B3 (subchron C5An.1r, MN 7, ca. 12.2 Ma); BCV1 and C3-A7 (subchron C5r.3r, MN 7, ca. 11.9 Ma); C5-C3 (subchron C5r.3r, MN 8, ca. 11.8 Ma); and C4-A1 (subchron C5r.3r; MN 8, ca. 11.7 Ma). The snake vertebral column can be subdivided into four basic regions (Szyndlar, 1984; see Fig. 1): cervical vertebrae, trunk vertebrae, cloacal vertebrae, and caudal vertebrae; cervical and trunk vertebrae are collec- tively referred to as precloacal vertebrae. The vertebral nomenclature used in this work follows Holman (2000, after Auffenberg, 1963; see Fig. 2). Snake vertebrae are procoelus, i.e. the cranial surface of the centrum (the co- tyle) is convex, while the caudal surface (the condyle) is spherical and concave. Like in other vertebrates, snake vertebrae are mainly composed by two principal structures: the centrum and the neural arch. These two main parts are important for classifying snakes at the super- family, or even family, levels, but they are not further informative at lower taxonomic ranks. In order to attain more precise taxonomic identi fi cations, the con fi gura- tion of the apophyses and other special structures (i.e., the prezygapophyseal accesory process, hypapophyses, pleurapophyses, etc.) must be taken into account. Of all the projecting parts of ophidian vertebrae, those taxono- mically more informative are the neural spine and the ventral projecting parts (i.e., hypapophyses, haemal keel and hemapophyses). Cervical vertebrae always display hypapophyses (a long ventral projection fused to the centrum). The trunk region displays ribs articulated with the vertebrae, whereas in the caudal region the ribs are fused to the vertebrae. Finally, both the cloacal and caudal vertebrae display hemapophyses (paired structures fused to the centrum), although the former further display lymphapophyses (fused, forked ribs), while the latter display pleurapophyses (fused, non- forked ribs). Ribs articulate with the synapophyses (also known as paradiapophyses), which are more or less subdivided into the dorsal diapophysis and the ventral parapophysis, depending on the taxa. Within the Colubridae, hypapohyses are present in all trunk vertebrae of the “Na- tricinae”, but are only present in the cervical vertebrae of the “Colubrinae”, whereas in the Elapidae and the Viperidae they are also present in all trunk vertebrae. As noted by Szyndlar (1991a), the traditional division of fossil Colubridae into two subfamilies, Colubrinae and Natricinae, based on the absence/presence of hypapophyses on postcervical thoracic vertebrae, partially contradicts the systematic divisions employed for extant taxa. As such, following Szyndlar (1991a), here we employ these terms informally, in order to refer to a particular vertebral morphology. In order to distinguish the Colubroidea, Elapoidea and Viperoidea from the Booidea, the CL/NAW ratio is usually employed, where CL is the centrum length and NAW is the centrum width (Fig. 1; after Auffenberg, 1963). CL is de fi ned as the distance between the cotyle lip and the end of the condyle, whereas NAW corre- sponds the width of the interzygapophyseal constriction. A CL/NAW ratio lower than 1 characterizes the Booidea, whereas the other groups display the opposite condition. Nevertheless, no reliable identi fi cations can be reached exclusively on the basis of metrical evidence (Szyndlar, 1984), so that morphological features are also required. Measurements were based on photographs taken with a Leica IC3D stereomicroscope and photocamera con- nected to a computer, with the software package Leica Application Suite v.2.8.1. All measurements are given in millimeters (mm). All the studied specimens are housed at the Institut Català de Paleontologia (Catalonia, Spain). A list of the studied specimens, further specifying the locality of prov- enance and the taxonomic and anatomical identi fi cation, is reported in Fig. 3. Several specimens were recovered during screen-washing the fossiliferous sediment, while others were recovered during manual ...

Context 2

... work intends to partially fi ll this gap on the knowledge of Miocene ophidians from Catalonia on the basis of recently recovered Late Aragonian material from the area of els Hostalets de Pierola (Vallès-Penedès Basin, Catalonia, Spain). In particular, the fossil remains reported here were recovered during the works of paleontolo- gical control and excavation carried out in the Abocador de Can Mata (ACM; see Alba et al., 2006a,b, 2007, 2009). To date, more than 43,000 large vertebrate remains and several thousands of microvertebrate remains have been recovered (Alba et al., 2009). Among others, this has led to the recovery of several ophidian vertebrae, although in many instances the fragmentary preservation precludes an accurate taxonomic attribution. In this work, we report the preliminary taxonomic attribution of the ophidian vertebral remains from the local series of ACM that have been thus far prepared for study. The sediments exposed on the ACM local stratigraphic series are mainly composed by clayish levels, sometimes with sandstone and conglomeratic levels intercalated. The clay levels are usually reddish to gold-yellowish co- loured, with a metric to decametric thickness. Nodules, pedogenic processes, bioturbation and decoloured marks are more or less common on this beds. These deposits are interpreted to have originated in alluvial-fan marginal to distal environments, with a fl uctuating radius span and transport ef fi ciency (Casanovas-Vilar et al., 2008). The series is about 300 m-thick and includes more than 150 fossil vertebrate localities (Alba et al., 2009), which can be accurately dated on the basis of lito-, bio- and mag- netostratigraphic data (Moyà-Solà et al., 2009). The series approximately ranges from 12.5 to 11.3 Ma, mainly corresponding to the MN 7 and MN 8 biozones (sensu Mein and Ginsburg, 2002: Late Aragonian, middle Miocene). The material described in this work comes from a total of six different localities, with the following estima- ted age: C2-B3 and C3-B3 (subchron C5An.1r, MN 7, ca. 12.2 Ma); BCV1 and C3-A7 (subchron C5r.3r, MN 7, ca. 11.9 Ma); C5-C3 (subchron C5r.3r, MN 8, ca. 11.8 Ma); and C4-A1 (subchron C5r.3r; MN 8, ca. 11.7 Ma). The snake vertebral column can be subdivided into four basic regions (Szyndlar, 1984; see Fig. 1): cervical vertebrae, trunk vertebrae, cloacal vertebrae, and caudal vertebrae; cervical and trunk vertebrae are collec- tively referred to as precloacal vertebrae. The vertebral nomenclature used in this work follows Holman (2000, after Auffenberg, 1963; see Fig. 2). Snake vertebrae are procoelus, i.e. the cranial surface of the centrum (the co- tyle) is convex, while the caudal surface (the condyle) is spherical and concave. Like in other vertebrates, snake vertebrae are mainly composed by two principal structures: the centrum and the neural arch. These two main parts are important for classifying snakes at the super- family, or even family, levels, but they are not further informative at lower taxonomic ranks. In order to attain more precise taxonomic identi fi cations, the con fi gura- tion of the apophyses and other special structures (i.e., the prezygapophyseal accesory process, hypapophyses, pleurapophyses, etc.) must be taken into account. Of all the projecting parts of ophidian vertebrae, those taxono- mically more informative are the neural spine and the ventral projecting parts (i.e., hypapophyses, haemal keel and hemapophyses). Cervical vertebrae always display hypapophyses (a long ventral projection fused to the centrum). The trunk region displays ribs articulated with the vertebrae, whereas in the caudal region the ribs are fused to the vertebrae. Finally, both the cloacal and caudal vertebrae display hemapophyses (paired structures fused to the centrum), although the former further display lymphapophyses (fused, forked ribs), while the latter display pleurapophyses (fused, non- forked ribs). Ribs articulate with the synapophyses (also known as paradiapophyses), which are more or less subdivided into the dorsal diapophysis and the ventral parapophysis, depending on the taxa. Within the Colubridae, hypapohyses are present in all trunk vertebrae of the “Na- tricinae”, but are only present in the cervical vertebrae of the “Colubrinae”, whereas in the Elapidae and the Viperidae they are also present in all trunk vertebrae. As noted by Szyndlar (1991a), the traditional division of fossil Colubridae into two subfamilies, Colubrinae and Natricinae, based on the absence/presence of hypapophyses on postcervical thoracic vertebrae, partially contradicts the systematic divisions employed for extant taxa. As such, following Szyndlar (1991a), here we employ these terms informally, in order to refer to a particular vertebral morphology. In order to distinguish the Colubroidea, Elapoidea and Viperoidea from the Booidea, the CL/NAW ratio is usually employed, where CL is the centrum length and NAW is the centrum width (Fig. 1; after Auffenberg, 1963). CL is de fi ned as the distance between the cotyle lip and the end of the condyle, whereas NAW corre- sponds the width of the interzygapophyseal constriction. A CL/NAW ratio lower than 1 characterizes the Booidea, whereas the other groups display the opposite condition. Nevertheless, no reliable identi fi cations can be reached exclusively on the basis of metrical evidence (Szyndlar, 1984), so that morphological features are also required. Measurements were based on photographs taken with a Leica IC3D stereomicroscope and photocamera con- nected to a computer, with the software package Leica Application Suite v.2.8.1. All measurements are given in millimeters (mm). All the studied specimens are housed at the Institut Català de Paleontologia (Catalonia, Spain). A list of the studied specimens, further specifying the locality of prov- enance and the taxonomic and anatomical identi fi cation, is reported in Fig. 3. Several specimens were recovered during screen-washing the fossiliferous sediment, while others were recovered during manual ...