Ichnogenus Batrachichnus Woodworth, Reference Woodworth1900
Ichnospecies Batrachichnus salamandroides (Geinitz, Reference Geinitz1861)

(Fig. 3; supplementary Appendix S2, Tables S1, S2, available at http://journals.cambridge.org/geo)

Material and stratigraphic position: In section MA-A1a, five fitting slabs ex situ with six tracks (marks and casts, i.e. both in concave and convex relief): IPS-73741, IPS-73742, IPS-73743, IPS-73744 and IPS-73745.

Description: The footprints are grouped in different manus-pes sets, but only one is nearly complete, settled in a trackway. The footprints are usually digitigrade or semiplantigrade, except for one that is plantigrade. All the ichnites are wider than long and terminate in rounded digit tips without claw marks. Three tracks present a shallow sole impression. In front of all the tracks there are scratches formed when digit tips dragged the surface to advance. Tracks of the manus (6×11mm) are presumably tetradactyl, whereas those of the pedes (8×12mm) are pentadactyl. The relative length of the digits is not significant (supplementary Appendix S2, Table S1, available at http://journals.cambridge.org/geo) and ichnites are rotated either inwards or outwards from the midline, without following any pattern. Pace angulations of the manus and the pedes are low (<60º), this being indicative of sprawling locomotion of the trackmaker.

Discussion: The small size of the ichnites (<20mm), the alternating sets, the low stride angulations, the tetradactyl manus and the rounded digits are diagnostic of the ichnospecies Batrachichnus salamandroides, known from Carboniferous – lower Permian deposits of France (Gand & Durand, Reference Gand, Durand, Lucas, Cassinis and Schneider2006), Germany (Voigt, Reference Voigt2005), New Mexico (Lucas et al. Reference Lucas, Minter, Spielmann, Hunt and Braddy2005; Voigt & Lucas, Reference Voigt and Lucas2015), Canada (Falcon-Lang et al. Reference Falcon-Lang, Gibling, Benton, Miller and Bashforth2010; Stimson, Lucas & Melason, Reference Stimson, Lucas and Melason2012) and Poland (Voigt et al. Reference Voigt, Niedźwiedzki, Raczyński, Mastalerz and Ptaszyński2012). The shape and the size of the extremities and the glenoacetabular distances (30–35mm) of branchiosaurids and micromelerpetontid temnospondyls and also lepospondyls are comparable to these footprints, so these groups are suggested to be trackmakers of B. salamandroides (Gand & Durand, Reference Gand, Durand, Lucas, Cassinis and Schneider2006; Voigt, Reference Voigt2012; E.M., personal observation).

Ichnogenus Limnopus Marsh, Reference Marsh1894
Ichnospecies Limnopus isp.

(Figs 4, 11b–d; supplementary Appendix S1, Figs S2a–c, S3; supplementary Appendix S2, Tables S3, S4, available at http://journals.cambridge.org/geo)

Material and stratigraphic position: In section MA-A1a, numerous tracks in concave epirelief at 10.20–10.50m and 10.90m (replica IPS-82606), one trackway composed of two manus-pes sets and one partial manus track (replica IPS-82608), 16 partial tracks at 18.15m and one slab ex situ partially covered with ten tracks (IPS-83730). In section MA-A1b, several tracks in concave epirelief at 12.00–13.00m. In section MA-B, numerous tracks in convex hyporelief at 15.00–18.00m, one slab ex situ with one manus-pes set (IPS-73724) and one large block ex situ not recovered.

Description: Two different track shapes are recognized. The first (Fig. 4a–f) consists of ichnites with rounded, clawless digit tips and shallow oval (wider than longer) palm and sole impressions, some with an expulsion rim. The manus tracks are semiplantigrade to plantigrade, and wider (43–54mm) than long (32–38mm). The ichnites are tetradactyl with wide digits. The relative digit length is I<II≤IV<III. The digits I, II and IV are slightly rotated inwards, whereas digit III is straighter. All the digits present a rounded to elliptical shape. The digits I and II are more deeply impressed than the others. The pedes are pentadactyl and plantigrade, slightly wider (50–57mm) than long (37–48mm), and with a sole sometimes U-shaped. The digits I–V divarication is over 100°. The digit relative length is I≤V<II<III<IV. The pedes digits are proportionally longer than those of the manus, and digit V is rotated outwards. The digit tips are rounded and deeply impressed. The average width is greater in the manus (53mm) than in the pes (50mm). This is probably caused by the uncommon preservation of complete pedes in the larger-size tracks (see Fig. 4a–d; supplementary Appendix S2, Table S3, available at http://journals.cambridge.org/geo). In some sets, the pedes partially overstep the manus (Fig. 4e, f). In the trackway, the manus impressions are rotated inwards and the pedes are deformed (Fig. 4a–d). The low pace angulation (69°) and the relative large trackway external width (322mm) indicate a sprawling posture of the trackmaker.

The second type of tracks (Figs 4g–i, 11d; 2 in Fig. 11b) is the most abundant: it is generally unguligrade, formed by rounded digit tip prints in groups of two to five (commonly formed by four digit tips), and is spreaded in an arc with widths similar to those of the first track shape (both morphologies present a width/length ratio of 0.6–0.8). Some tip impressions show an expulsion rim in their posterior part. Some tracks appear as semiplantigrade because a very shallow sole or palm impression is preserved. Some digit tip prints are anteriorly elongated and slightly curved inward (i.e. scratches), with a similar track pattern than that of the previously described Batrachichnus salamandroides. At 17.75m in section MA-B, a well-defined trackway is formed by digit tip prints that are in contact with one another and present pace angulations of 92° (supplementary Appendix S1, Fig. S3 and Appendix S2, Table S4, available at http://journals.cambridge.org/geo).

Discussion: The two described track shapes belong to the same ichnotaxon because they present analogue proportions and some transitions between the two morphologies were found; they therefore represent different preservational states (Fig. 4a, h, i). The tetradactyl manus with a wide, large palm impression, the rounded clawless digit tips, the relative digit lengths, the pentadactyl pedes with a shallow impression of digit V and a U-shaped sole, as well as the pace angulations, are diagnostic of the ichnogenus Limnopus (e.g. Baird, Reference Baird1952; Gand, Reference Gand1988; Tucker & Smith, Reference Tucker and Smith2004; Voigt, Reference Voigt2005; Marchetti, Avanzini & Conti, Reference Marchetti, Avanzini and Conti2013; Voigt & Haubold, Reference Voigt and Haubold2015). Specimens reported here are different from those assigned to Batrachichnus salamandroides; there are two discrete populations of size (supplementary Appendix S2, Tables S1, S3, available at http://journals.cambridge.org/geo), indicating no transition between both ichnogenera. The 3D model analyses reveal that within all tracks the manus digits I and II are the most deeply impressed, probably because they are the most functional as suggested in other ichnogenera (Avanzini et al. Reference Avanzini, Neri, Nicosia and Conti2008). This is also indicated by the inwards orientation of the manus footprints, an uncommon feature in the ichnogenus in which the manus is often parallel to the midline (Voigt, Reference Voigt2005; Fig. 4a–f). Similar specimens are found in the upper Carboniferous deposits of England (Tucker & Smith, Reference Tucker and Smith2004) and the lower Permian deposits of France (Gand, Reference Gand1988; Demathieu et al. Reference Demathieu, Gand and Toutin-Morin1992), Italy (Marchetti et al. Reference Marchetti, Ronchi, Santi, Schirolli and Conti2015 a, b), Germany (Haubold, Reference Haubold1970, Reference Haubold1971; Voigt, Reference Voigt2005) and North America (Baird, Reference Baird1952). Haubold (Reference Haubold2000) only considered the ichnospecies L. vagus, L. zeilleri and L. cutlerensis (see also Voigt, Reference Voigt2005) to be of possible ichnotaxonomic value. Recently, Lucas & Dalman (Reference Lucas and Dalman2013) identified L. heterodactylus as the first described ichnospecies; it should therefore be used instead of L. vagus in case of synonymy (see also Marchetti, Avanzini & Conti, Reference Marchetti, Avanzini and Conti2013). Nevertheless, due to the preservation of the specimens described here, ichnospecies remain uncertain. The potential trackmakers for Limnopus are temnospondyl amphibians similar to eryopsids (Gand, Reference Gand1988; Van Allen et al. Reference Van Allen, Calder and Hunt2005; Voigt, Reference Voigt2005; Gand & Durand, Reference Gand, Durand, Lucas, Cassinis and Schneider2006).

Ichnogenus cf. Amphisauropus Haubold, Reference Haubold1970

(Figs 5, 11c; supplementary Appendix S1, Fig. S2d–l and Appendix S2, Table S5, available at http://journals.cambridge.org/geo)

Material and stratigraphic position: In section MA-B, at 15.00–15.20m, 16.00m, 16.50m, 17.75m (replica IPS-82605), 21.50m and 23.80m, as well as one slab ex situ with one manus and three partial pes digits (IPS-73723). All the tracks are in convex hyporelief.

Description: The ichnites are coupled in manus-pes sets. The manus are plantigrade to semiplantigrade and wider (31–52mm) than long (19–39mm). They are pentadactyl with short digits terminated in rounded and relatively large clawless digit tips, more deeply impressed than the rest of the footprint (Fig. 5). The digit length increases from digit I to IV. The length of digit V is similar to that of I. The pedes, larger than the manus, are plantigrade to semiplantigrade and pentadactyl. They are longer (32–57mm) than wide (27–51mm) and their digit length increases from I to IV. The length of digit V falls between those of I and II. The digits III and IV are the longest. Commonly, digits III and IV are the most deeply impressed followed by digits I and II, while digit V is not always preserved. In sets, the pedes never overstep the manus; the latter are rotated inwards at approximately 90° from the pes orientation (i.e. the manus width axis is aligned with the pes length axis; supplementary Appendix S1, Fig. S2j–l, available at http://journals.cambridge.org/geo).

Discussion: The plantigrade to semiplantigrade pentadactyl tracks with broad sole, the rounded digit tips, the measured relative digit lengths, the manus sensibly wider than long and inwards-oriented with respect to the pes (supplementary Appendix S2, Table S5, available at http://journals.cambridge.org/geo) are diagnostic traits of Amphisauropus (see Haubold, Reference Haubold1970; Voigt, Reference Voigt2005). However, this assignation remains tentative due to the lack of trackways, and the overall poor preservation of the specimens. The specimens from the site MA-B present shorter and more robust digits than tracks assignable to A. kablikae (the only valid ichnospecies sensu Voigt, Reference Voigt2005) described by Haubold (Reference Haubold1970, Reference Haubold1971), Gand (Reference Gand1988), Nicosia, Ronchi & Santi (Reference Nicosia, Ronchi and Santi2000), Lucas, Lerner & Haubold (Reference Lucas, Lerner and Haubold2001), Lucas, Spielmann & Lerner (Reference Lucas, Spielmann, Lerner, Lueth, Lucas and Chamberlain2009), Van Allen et al. (Reference Van Allen, Calder and Hunt2005), Voigt (Reference Voigt2005, Reference Voigt2012), Avanzini et al. (Reference Avanzini, Neri, Nicosia and Conti2008), Voigt et al. (Reference Voigt, Lagnaoui, Hminna, Saber and Schneider2011 a, Reference Voigt, Niedźwiedzki, Raczyński, Mastalerz and Ptaszyński2012), Marchetti et al. (Reference Marchetti, Ronchi, Santi, Schirolli and Conti2015 a, b). The Pyrenean specimens are smaller (but similar in shape) than those assigned to Amphisauropus isp. by Hminna et al. (Reference Hminna, Voigt, Saber, Schneider and Hmich2012) in the Argana Basin (Morocco). According to Lucas, Lerner & Haubold (Reference Lucas, Lerner and Haubold2001) and Voigt (Reference Voigt2005), the trackmakers of Amphisauropus could belong to the seymouriamorph group.

Ichnogenus cf. Ichniotherium Pohlig, Reference Pohlig1892

(Fig. 6; supplementary Appendix S2, Table S6, available at http://journals.cambridge.org/geo)

Material and stratigraphic position: In section MA-B, at 23.20m, at least 16 tracks in convex hyporelief.

Description: The footprints are pentadactyl and plantigrade, with a characteristic oval-shaped laterally expanded sole impression. The digits are preserved as rounded impressions. The tips are the most deeply impressed parts, and often the only preserved parts. Some tracks only preserve the sole or some digit tips. The digits relative length is I<II≤V<III<IV, and the sole impression is opposite to digits II–V. At least two manus-pes sets are preserved and partial trackways can be established, although these groupings remain tentative due to the partial preservation of most of the footprints.

Discussion: The position and shape of the sole and the assumed morphology and length of the digits can be tentatively attributed to cf. Ichniotherium (see Voigt, Berman & Henrici, Reference Voigt, Berman and Henrici2007). This ichnogenus, common in German basins (Voigt, Reference Voigt2005; Voigt, Berman & Henrici, Reference Voigt, Berman and Henrici2007), has also been reported in the French basin of Lodève (Gand & Durand, Reference Gand, Durand, Lucas, Cassinis and Schneider2006), the Moroccan basin of Khenifra (Voigt et al. Reference Voigt, Saber, Schneider, Hmich and Hminna2011 b), Colorado (Voigt, Small & Sanders, Reference Voigt, Small and Sanders2005), New Mexico (Lucas et al. Reference Lucas, Voigt, Lerner and Nelson2011) and Canada (Brink, Hawthorn & Evans, Reference Brink, Hawthorn and Evans2012). The specimens described here are preserved in a different substrate (tabular bed, coarser with rough aspect), formed in drier conditions than the rest of the strata bearing footprints, which suggests different palaeoenvironmental conditions associated with this ichnospecies. This is in concordance with the attribution of Ichniotherium to inland zones (e.g. Brink, Hawthorn & Evans, Reference Brink, Hawthorn and Evans2012), being separated from ichnotaxa commonly found in wetter environments. The trackmakers assigned to Ichniotherium are most probably early amniote diadectids (Voigt, Berman & Henrici, Reference Voigt, Berman and Henrici2007).

Ichnogenus Dromopus Marsh, Reference Marsh1894
Ichnospecies Dromopus isp.

(Fig. 7; supplementary Appendix S2, Table S7, available at http://journals.cambridge.org/geo)

Material and stratigraphic position: In section MA-B, at 22.40m, six footprints in convex hyporelief.

Description: Of the six isolated footprints described here, four of them preserve only two digit impressions, another is composed of three digits and the last is presumably pentadactyl. The largest ichnite is 22.7mm in length, and the relative digits length increases from digit II to IV. The digits are relatively long with pointed tips, indicating the presence of claws. The digits are slightly curved inward. The digits III and IV are the most deeply impressed, followed by the digit II. The digit IV is remarkably longer than the digit III. Mean divarication of the digits III and IV is 24.8°.

Discussion: The shape of the digits as well as their relative length (with the digit IV sensibly longer than the digit III) and the deeper impression of digits III and IV are diagnostic traits of the ichnogenus Dromopus. It is the most widespread ichnotaxon in early Permian and Carboniferous basins (Voigt, Reference Voigt2005); similar specimens have been reported from German (Voigt, Reference Voigt2005), Polish (Voigt et al. Reference Voigt, Niedźwiedzki, Raczyński, Mastalerz and Ptaszyński2012), Italian (Avanzini, Bernardi & Nicosia, Reference Avanzini, Contardi, Ronchi and Santi2011; Marchetti et al. Reference Marchetti, Ronchi, Santi, Schirolli and Conti2015 a, b), French (Gand, Reference Gand1988; Gand & Durand, Reference Gand, Durand, Lucas, Cassinis and Schneider2006), Moroccan (Voigt et al. Reference Voigt, Lagnaoui, Hminna, Saber and Schneider2011 a, b) and also North American (Van Allen et al. Reference Van Allen, Calder and Hunt2005; Lucas et al. Reference Lucas, Voigt, Lerner and Nelson2011; Voigt & Lucas, Reference Voigt and Lucas2015) basins. Dromopus specimens described here are commonly preserved as incomplete didactyl tracks; there is therefore still no consensus on possible ichnospecific differentiations due to the lack of diagnostic traits. The trackmakers referred to Dromopus are small- to medium-sized sauropsids, in particular araeoscelids and bolosaurids (Voigt et al. Reference Voigt, Niedźwiedzki, Raczyński, Mastalerz and Ptaszyński2012).

Ichnogenus cf. Varanopus Moodie, Reference Moodie1929

(Fig. 8; supplementary Appendix S2, Tables S8, S9, available at http://journals.cambridge.org/geo)

Material and stratigraphic position: In section MA-A1a, at 10.50m (replica IPS-82607), eight tracks settled in a trackway in concave epirelief.

Description: The trackway is composed of eight tracks grouped in four manus-pes sets. The footprints have an expulsion rim, higher in the outer or lateral sides of the trackway than in the inner side. Both manus and pedes are probably pentadactyl and semiplantigrade. The digits I–IV are curved inwards (more in manus than in pes tracks) with pointed and sharply curved tips, indicating the presence of claws. The digit length increases from digit I to IV, digit V length in pedes is uncertain and in manus it is similar to the length of digit I.

The manus tracks are slightly wider than long (39×38mm) with divarication of digits I–V over 130°, whereas the pedes are longer than wide (24×31mm) with the divarication of digits I–V less than 90° (supplementary Appendix S2, Table S8, available at http://journals.cambridge.org/geo). The pes tracks appear smaller than the manus tracks, but this corresponds to extramorphological variation (see following discussion). The third set is situated in the surface of the layer below the other ichnites, and therefore corresponds to an undertrack. The manus is a highly deformed shallow footprint, much longer than wide. The preserved digits are also wider, and the digit tips are sharply curved inwards and pointed as in the other manus ichnites. The pes track is a shallow impression outlined by a low expulsion rim. The manus tracks, on average 47mm distant from the pedes, are slightly rotated inwards towards the trackway midline. The manus tracks are generally more deeply impressed than the pedes tracks and with higher expulsion rims. The trackway parameters are similar in manus and pedes. The pace angulations indicate a sprawling locomotion (<90°).

Discussion: The shape of the digits (rotated inwards with curved clawed tips), the measured relative lengths of the digits, the divarication of digits I–V, the stride angulation and the stride/pes length proportion (supplementary Appendix S2, Tables S8, S9, available at http://journals.cambridge.org/geo) are diagnostic traits of Varanopus (sensu Haubold & Lucas, Reference Haubold and Lucas2003; Voigt, Reference Voigt2005; Voigt & Haubold, Reference Voigt and Haubold2015), but due to the poor preservation of the tracks the assignation should remain tentative. These tracks resemble those reported by Moodie (Reference Moodie1929, p. 364–5) (a single set) or those of further studies (e.g. Haubold, Reference Haubold1971; Gand, Reference Gand1988; Nicosia, Ronchi & Santi, Reference Nicosia, Ronchi and Santi2000; Haubold & Lucas, Reference Haubold and Lucas2001, Reference Haubold and Lucas2003; Lucas, Spielmann & Lerner, Reference Lucas, Spielmann, Lerner, Lueth, Lucas and Chamberlain2009; Voigt, Reference Voigt2005, Reference Voigt2012; Voigt, Small & Sanders, Reference Voigt, Small and Sanders2005; Marchetti et al. Reference Marchetti, Ronchi, Santi, Schirolli and Conti2015 a, b). The sets show that the pes tracks are smaller than the manus tracks, and the manus palms are much deeper than the digits. These traits are probably due to substrate conditions, with a trackmaker possibly advancing on the substrate under water level (on this surface there are also swimming scratches). The elongated manus undertrack from the third set indicates a dragging component of the manus on the substrate surface, due to a strong limb impression of the trackmaker. This ichnotaxon is found in several early Permian localities from Europe and North America and potentially from Morocco (see Voigt et al. Reference Voigt, Lagnaoui, Hminna, Saber and Schneider2011 a for discussion). The trackmakers assigned to this ichnotaxon could be eureptiles such as captorhinids (Haubold & Lucas, Reference Haubold and Lucas2003; Voigt, Reference Voigt2005; Gand & Durand, Reference Gand, Durand, Lucas, Cassinis and Schneider2006).

Ichnogenus Hyloidichnus Gilmore, 1927
Ichnospecies Hyloidichnus isp.

(Fig. 9; supplementary Appendix S2, Table S10, available at http://journals.cambridge.org/geo)

Material and stratigraphic position: In section MA-A2, four tracks in the surface at 7.30m and ten tracks in the surface at 7.90m. All the tracks are in concave epirelief.

Description: Four manus-pes sets have been identified. The manus impressions are closer and slightly rotated to a hypothetical trackway midline (although there are no true trackways preserved). The manus lengths and widths are 41–75mm and 69–84mm, respectively. The digit V is often not preserved, and track widths cannot always be measured. The pes tracks are slightly larger than the manus tracks (supplementary Appendix S2, Table S10, available at http://journals.cambridge.org/geo). The digits are relatively large and straight with wide and rounded to T-shaped tips. The digit V is directed outwards. The digit relative length is V<I<II<III<IV and the digit depth impression decreases from digit I to V. The ichnites in the surface at 7.90m are semiplantigrade to plantigrade (Fig. 9a–c) and those at 7.30m are digitigrade to semiplantigrade (Fig. 9e, f).

Discussion: The two surfaces yield tracks with different preservation, probably because of different substrate conditions at the moment of the track impression; the lower-level surface might have been dryer and harder than the upper level because the ichnites from the former are shallower than those from the latter, and with less features preserved. Despite these differences in preservation, these tracks correspond to the same ichnogenus as they have similar digit morphology, relative length and divarication (supplementary Appendix S2, Table S10, available at http://journals.cambridge.org/geo). Based on the manus/pes proportions, the slender digits with wider tips, the relative digit length (with a relatively short pes digit V) and impression depth and the size of the digits in relation to the shallow sole and palm impressions, these footprints are assigned to Hyloidichnus (see Gilmore, Reference Gilmore1927; Haubold, Reference Haubold1971; Gand, Reference Gand1988). Material referred to Hyloidichnus was previously described by Voigt & Haubold (Reference Voigt and Haubold2015) in a locality nearby to MA-A2. However, the specimens described here are larger in size (up to lengths of 68.9mm in the manus and 74.5mm in the pedes). The ichnospecies identification remains uncertain due to the lack of trackways and because there is still no consensus on the ichnospecific differentiation (e.g. Gand, Reference Gand1988; Marchetti, Avanzini & Conti, Reference Marchetti, Avanzini and Conti2013). Hyloidichnus has been reported in Permian deposits of Peña Sagra, Spain (Gand et al. Reference Gand, Kerp, Parsons and Martínez-García1997), Argana, Morocco (Voigt et al. Reference Voigt, Hminna, Saber, Schneider and Klein2010; Hminna et al. Reference Hminna, Voigt, Saber, Schneider and Hmich2012), Italy (Avanzini, Bernardi & Nicosia, Reference Avanzini, Contardi, Ronchi and Santi2011; Marchetti, Avanzini & Conti, Reference Marchetti, Avanzini and Conti2013; Marchetti et al. Reference Marchetti, Ronchi, Santi, Schirolli and Conti2015 b), France (Gand, Reference Gand1988; Gand, Reference Gand1993; Gand & Durand, Reference Gand, Durand, Lucas, Cassinis and Schneider2006) and North America (Gilmore, Reference Gilmore1927; Lucas et al. Reference Lucas, Krainer, Chaney, DiMichele, Voigt, Berman and Henrici2013). The possible Hyloidichnus trackmakers are captorhinid eureptiles (Voigt et al. Reference Voigt, Hminna, Saber, Schneider and Klein2010; Hminna et al. Reference Hminna, Voigt, Saber, Schneider and Hmich2012).

Ichnogenus Dimetropus Romer & Prince Reference Romer and Price1940
Ichnospecies Dimetropus leisnerianus (Geinitz, Reference Geinitz1863)

(Fig. 10; supplementary Appendix S1, Fig. S2m-o; Appendix S2, Table S11, available at http://journals.cambridge.org/geo)

Material and stratigraphic position: In section MA-A2, two manus-pes sets at 8.60m. In section MA-A3, one manus-pes set at 4.70m. All the tracks are in concave epirelief.

Description: The manus-pes sets are formed by plantigrade pentadactyl ichnites. The palm and sole impressions are deep and the digit shape is not well preserved. The tracks are similar in length and width. The pedes impressions (120–135mm in length) are larger than the manus impressions (102–120mm in length). The digits of the manus are long (c. 40% of track length) and straight with similar divarication. The relative length of the digits is I<II≤V<III<IV. Digits of the manus have the lateral walls collapsed, indicative of a saturated substrate. The digits of the pedes are short in relation to sole length and width, and in digit IV of the second set there is a shallow claw impression. The manus palms and the pedes soles are more deeply impressed than the digits, indicating a strong plantigrade track. The ichnites from section MA-A2 seem to correspond to the same trackway, as the tracks are rotated towards a hypothetical trackway midline (Fig. 10). The footprints from section MA-A3 are deformed (supplementary Appendix S1, Fig. S2m–o, available at http://journals.cambridge.org/geo), but they have been identified because of the similarity in shape to those of MA-A2 although the pes is just a shallow sole impression and in the manus only two digits are well distinguished. The cause of the low preservation quality of the ichnites from section MA-A3 is probably due to the runoff water circulation soon after their impression.

Discussion: The size of the plantigrade footprints with large, rounded, deep palm and sole impressions (>50% of track length), the straight digits with claw marks (although shallow), the relative digit length, the divarication of digits I–V and the manus-pes proportion are diagnostic traits of Dimetropus leisnerianus (see Voigt, Reference Voigt2005). This ichnogenus is known from Permian tracksites from northern land masses (e.g. Haubold, Reference Haubold1971, Reference Haubold1984; Gand, Reference Gand1988; Van Allen et al. Reference Van Allen, Calder and Hunt2005; Voigt, Reference Voigt2005; Lucas et al. Reference Lucas, Voigt, Lerner and Nelson2011, Reference Lucas, Krainer, Chaney, DiMichele, Voigt, Berman and Henrici2013; Voigt et al. Reference Voigt, Niedźwiedzki, Raczyński, Mastalerz and Ptaszyński2012) and also from Tiddas (Voigt et al. Reference Voigt, Lagnaoui, Hminna, Saber and Schneider2011 a) and Khenifra basins (Voigt et al. Reference Voigt, Saber, Schneider, Hmich and Hminna2011 b) in Morocco. Dimetropus also appears in German early Carboniferous sites (Voigt & Ganzelewski, Reference Voigt and Ganzelewski2010). The pelycosaur synapsids, including caseids, edaphosaurids, ophiacodontids and sphenacodontids, are traditionally considered as the trackmakers of Dimetropus (Haubold, Reference Haubold1971, Reference Haubold2000; Gand, Reference Gand1988; Voigt, Reference Voigt2005; Voigt et al. Reference Voigt, Lagnaoui, Hminna, Saber and Schneider2011 a, b).

Ichnogenus Characichnos Whyte & Romano Reference Whyte and Romano2001
Ichnospecies Characichnos isp.

(Fig. 11; supplementary Appendix S1, Fig. S3, available at http://journals.cambridge.org/geo)

Material and stratigraphic position: Type A (associated with Batrachichnus salamandroides): one slab ex situ (IPS-73739) from site MA-A1a, the tracks are in convex hyporelief. In section MA-B, numerous tracks in convex hyporelief at 16.80m, one slab ex situ with Acripes multiformis and Rusophycus isp. at the uppermost surface (IPS-73726) and one slab ex situ not recovered. Type B (associated with Limnopus isp.): in section MA-A1a, numerous tracks in concave epirelief at 10.20–10.50m and 10.90m (replica IPS-82606). In section MA-A1b, several tracks in concave epirelief at 12.00–13.00m. In section MA-B, numerous tracks in convex hyporelief at 15.00–18.00m (replica IPS-82604 at 17.50m), 20.10–20.30m and 23.00m, and one large block ex situ not recovered. Type C (associated with cf. Amphisauropus): in section MA-B, numerous tracks in convex hyporelief at the upper part of the surface at 17.75m.

Description: Where present, these ichnites are abundant. Three groups of ichnites differing in shape and size can be recognized.

Type A. The tracks are composed of relatively large and narrow (1×5–20mm) scratches (digit tip prints dragged on the surface). Most of them are sinuous, although some are straight. A hooked end is present in some scratches. The tracks have a maximum of four scratches, but usually three. Two different track sizes are present: 10mm width or 5–6mm. Although most of the tracks are aligned in the same direction, no clear groups of tracks or trackway patterns can be identified due to the high abundance of tracks, which usually overstep one another. In some parts in section MA-B at 16.80m (Fig. 11a) scratches have no preferential directions and are accompanied by invertebrate trace fossils (Acripes multiformis and arthropod body impressions; Fig. 1c), and sometimes also by larger scratches of Type B.

Type B. The ichnites are formed by two, three or four digit scratches slightly curved or sinuous (Fig. 11b–e). Tracks with two scratches are usually in contact. The scratch associated with each digit measures 10mm in width and 30–60mm in length. In most surfaces these tracks are isolated or accompanied by digit tip tracks of the second morphology of Limnopus isp., except in the surface at 17.50m in section MA-B which is plenty of scratches aligned in the same direction (Fig. 11c). Some scratches present a hooked end (Fig. 11e) such as those of Type A. At 10.35m in section MA-A1a there are several scratches and digit tip tracks of Limnopus isp. displayed in different trackways, demonstrating the association between these swimming traces and Limnopus isp. Some of these scratches have a large expulsion rim on the posterior part, suggesting an anteroposterior limb movement.

Type C. These scratches measure in average 5×25mm. They are usually in groups of three digit scratches, or in some case with a fourth print (Fig. 11c, f). Traces of this morphotype are smaller and relatively narrower than those of Type B. In the surface at 17.75m from section MA-B there is a transition from cf. Amphisauropus to these scratches, in some cases impressed by the same trackmaker individual (Fig. 11c). Swimming traces appear largely abundant, also with some digit tip imprints of Limnopus isp. (supplementary Appendix S1, Fig. S3, available at http://journals.cambridge.org/geo).

Discussion: Swimming scratches with the same shapes and range of sizes are referred to the ichnogenus Characichnos defined by Whyte & Romano (Reference Whyte and Romano2001). Scratches similar to Type A have been associated with tracks of Batrachichnus salamandroides described by Lucas et al. (Reference Lucas, Voigt, Lerner and Nelson2011). These three types of scratches are interpreted as swimming traces (Gand, Reference Gand1989; Whyte & Romano, Reference Whyte and Romano2001; Melchor & Sarjeant, Reference Melchor and Sarjeant2004; Gand et al. Reference Gand, Tüysüz, Steyer, Allain, Sakınç, Sanchez, Șengor and Sen2011; Lucas et al. Reference Lucas, Voigt, Lerner and Nelson2011; Lovelace & Lovelace, Reference Lovelace and Lovelace2012). The hooked ends observed in Types A and B show the changing direction of the limb when it was being raised up, indicating that the trackmaker was probably swimming close to the substrate. The superimposition of different specimens renders the identification of the trackway pattern impossible due to the contact of trackmakers with substrate, which was not regular. The associations of scratches with Batrachichnus salamandroides, Limnopus isp. and cf. Amphisauropus indicate a transition of walking to swimming locomotion of the trackmakers, probably due to a transition of relatively shallow to relatively deep water. The potential trackmakers of these swimming traces are probably those of the associated walking gait footprints: branchiosaurids and micromelerpetontid temnospondyls and lepospondyls for Type A; large temnospondyls for Type B; and seymouriamorphs for Type C.