Table summarizing results of all phylogenetic analyses carried out for the Parrsboro jaw, NSM 987GH65.1.

<p>Table summarizing results of all phylogenetic analyses carried out for the Parrsboro jaw, NSM 987GH65.1.</p

Redescription and Phylogenetic Analysis of the Mandible of an Enigmatic Pennsylvanian (Late Carboniferous) Tetrapod from Nova Scotia, and the Lability of Meckelian Jaw Ossification

<div><p>The lower jaw of an unidentified Pennsylvanian (Late Carboniferous) tetrapod from Nova Scotia – the “Parrsboro jaw”- is redescribed in the light of recent tetrapod discoveries and work on evolution of tetrapod mandibular morphology and placed for the first time in a numerical cladistics analysis. All phylogenetic analyses place the jaw in a crownward polytomy of baphetids, temnospondyls, and embolomeres. Several features resemble baphetids and temnospondyls including dermal ornamentation, absence of coronoid teeth, and presence of coronoid shagreen. Dentary dentition is most similar to <i>Baphetes</i>. An adsymphysial toothplate may not preclude temnospondyl affinity. An apparent large exomeckelian fenestra, with the dorsal foraminal margins formed by an unossified element, echoes the morphology of the stem tetrapod <i>Sigournea</i> and is unusually primitive given the other features of the jaw. The jaw may thus provide an example of an intermediate stage in Meckelian element evolution.</p></div

Anterior portion of the Parrsboro jaw, NSM 987GH65.1, in dorsal view.

<p>A, photograph of peel of anterior of natural mould of jaw loaned to JAC in dorsal view; B, interpretative line drawing of anterior of jaw in dorsal view; C, alternative interpretative line drawing of anterior jaw in dorsal view, with denticulated element below anterior coronoid interpreted as splenial rather than prearticular. adsym, adsymphyseal toothplate; adsym fang, adsymphyseal fang; ant cor, anterior coronoid; dent, dentary; dent fang, dentary fang; mid cor, middle coronoid; ?mid-post cor s., possible suture between middle and posterior coronoids; orn, ornamentation; ?post cor, possible posterior coronoid; preart, prearticular; spl, splenial. Hollow circular stippling indicates denticulation.</p

Interpretive line drawings of the anterior of the Parrsboro jaw, NSM 987GH65.1, modified from <b>fig. 1</b> of Godfrey and Holmes (1989).

<p>A, dorsal view; B, medial view. adsym, adsymphyseal tooth plate; ang, angular; cor, coronoid; dent, dentary; pospl, postsplenial; preart, prearticular.</p

Anterior portion of the Parrsboro jaw, NSM 987GH65.1, in medial view.

<p>A, photograph of anterior part of jaw natural mould peel loaned to JAC in medial view; B, interpretative line drawing of anterior part of jaw in medial view; C, alternative interpretative line drawing of anterior jaw in medial view, with denticulated element below anterior coronoid interpreted as splenial rather than prearticular. adsym, adsymphyseal toothplate; adsym fang, adsymphyseal fang; ant cor, anterior coronoid; dent, dentary; dent fang, dentary fang; meck for, Meckelian foramina; meck, unossified Meckelian element; mid cor, middle coronoid; ?mid-post cor s., possible suture between middle and posterior coronoids; pospl, postsplenial; ?post cor, possible posterior coronoid; preart, prearticular; spl, splenial. Hollow circular stippling indicates denticulation.</p

Close up of prearticular of the Parrsboro jaw, NSM 987GH65.1.

<p>The dorsal section of prearticular can be seen to have been displaced so that its medial surface faces ventromedially. mid cor, middle coronoid; ?post cor, possible posterior coronoid; preart, prearticular.</p

Additional file 1: of Homeotic transformations reflect departure from the mammalian ‘rule of seven’ cervical vertebrae in sloths: inferences on the Hox code and morphological modularity of the mammalian neck

Figure S1. Results of cluster analysis for each specimen. A three subunit pattern was revealed in all specimens analyzed. Green, axis; yellow, anterior subunit; red, posterior subunit. A, C. cf. didactylus 1; B, C. didactylus 2; C, B. variegatus; D, B. tridactylus. Figure S2. 3D renderings of all analyzed vertebrae. For each specimen left lateral view above and anterior view below. A, C. cf. didactylus 1; B, C. didactylus 2; C, B. variegatus; D, B. tridactylus. C1 (atlas) of B. tridactylus was not available with the museum specimen. Note that the present analysis involved only postatlantal CV. Figure S3. Landmark set used in the 3D geometric morphometric analysis. The numbered 3D landmarks (red points) are shown on a mid-cervical vertebra of Bradypus tridactylus (3D model). LM1 = dorsal-anterior edge of vertebral centrum, LM2 = ventral-anterior edge of vertebral centrum, LM3 = ventral-posterior edge of vertebral centrum, LM4 = dorsal-posterior edge of vertebral centrum, LM5 = anteriormost edge of articular facet of postzygapophysis, LM6 = dorsal-posterior edge of articular facet of postzygapophysis, LM7 = point of maximum curvature between postzygapophysis and neural spine, LM8 = posterior edge of neural spine, LM9 = anterior edge of neural spine, LM10 = point of maximum curvature between neural spine and prezygapophysis, LM11 = posteriormost point of articular facet of prezygapophysis, LM12 = dorsal-anterior edge of articular facet of prezygapophysis, LM13 = dorsalmost point of vertebral centrum in anterior view, LM14 = lateralmost point of vertebral centrum in anterior view, LM15 = ventralmost point of vertebral centrum in anterior view. Table S1. Percentage of total variance explained and cumulative variance per relative warp (RW). Only the first four RWs are indicated since they explain more than 95% of the total variance. (DOCX 578 kb