Full Terms & Conditions of access and use can be found at https://www.tandfonline.com/action/journalInformation?journalCode=gich20 Ichnos An International Journal for Plant and Animal Traces ISSN: 1042-0940 (Print) 1563-5236 (Online) Journal homepage: https://www.tandfonline.com/loi/gich20 Proposal for Ichnotaxonomic Allocation of Therapsid Footprints from the Botucatu Formation (Brazil) Simone D'Orazi Porchetti, Reinaldo J. Bertini & Max C. Langer To cite this article: Simone D'Orazi Porchetti, Reinaldo J. Bertini & Max C. Langer (2018) Proposal for Ichnotaxonomic Allocation of Therapsid Footprints from the Botucatu Formation (Brazil), Ichnos, 25:2-3, 192-207, DOI: 10.1080/10420940.2017.1308929 To link to this article: https://doi.org/10.1080/10420940.2017.1308929 Published online: 19 Apr 2017. Submit your article to this journal Article views: 120 View Crossmark data Citing articles: 2 View citing articles https://www.tandfonline.com/action/journalInformation?journalCode=gich20 https://www.tandfonline.com/loi/gich20 https://www.tandfonline.com/action/showCitFormats?doi=10.1080/10420940.2017.1308929 https://doi.org/10.1080/10420940.2017.1308929 https://www.tandfonline.com/action/authorSubmission?journalCode=gich20&show=instructions https://www.tandfonline.com/action/authorSubmission?journalCode=gich20&show=instructions http://crossmark.crossref.org/dialog/?doi=10.1080/10420940.2017.1308929&domain=pdf&date_stamp=2017-04-19 http://crossmark.crossref.org/dialog/?doi=10.1080/10420940.2017.1308929&domain=pdf&date_stamp=2017-04-19 https://www.tandfonline.com/doi/citedby/10.1080/10420940.2017.1308929#tabModule https://www.tandfonline.com/doi/citedby/10.1080/10420940.2017.1308929#tabModule Proposal for Ichnotaxonomic Allocation of Therapsid Footprints from the Botucatu Formation (Brazil) Simone D’Orazi Porchettia, Reinaldo J. Bertinib, and Max C. Langer a aDepartment of Biology, Faculty of Sciences and Letters of Ribeir~ao Preto, Univeristy of S~ao Paulo, SP - Brazil; bCenter for Vertebrate Evolution and Paleobiology, Department of Applied Geology, Institute of Geosciences and Exact Sciences, S~ao Paulo State University (UNESP) - Campus Rio Claro, SP - Brazil ABSTRACT A new ichnospecies, Brasilichnium anaiti, is erected on material from the Botucatu Formation of Brazil. The general morphology supports ichnotaxonomic similarity between the new ichnotaxon and Brasilichnium elusivum Leonardi, 1981, even if a separation at the ichnospecies level is evident, based on differences in shape and arrangement of pes digit marks along with a clear dimensional gap between both ichnotaxa. Similar forms from the Lower Jurassic of the United States are known and should be included under this new ichnotaxonomic label, based on shared morphological features. B. anaiti is constantly associated with B. elusivum in dune foresets of hyperarid paleoenvironments, to which these forms are restricted. This makes B. anaiti a further element of the Brasilichnium ichnocoenosis in the larger framework of the Chelichnus ichnofacies. Re– evaluation of possible trackmakers highlights the difficulties of unequivocal referring this ichnotaxon to a specific producer, but restrains potential trackmakers to early mammaliamorph therapsids. KEYWORDS Botucatu Formation; Brasilichnium anaiti; Brazil; Mammaliamorph therapsids; Paleoerg Introduction With extensive work of collection and description of verte- brate footprints, Leonardi (1977a, 1977b, 1980, 1981, 1989, 1994) and coworkers (Leonardi and Godoy, 1980; Leonardi and Sarjeant, 1986; Leonardi and Oliveira, 1990; Leonardi and Carvalho, 1999; Leonardi et al., 2007) have greatly improved our knowledge of the Brazilian Mesozoic ichno- logical record. Brasilichnium elusivum (Leonardi, 1981) is probably the most renowned ichnotaxon erected on Brazil- ian material, a name successively adopted to identify ichn- ites from the Early Jurassic of North America (see Lockley, 2011). Nonetheless, quadrupedal morphotypes other than B. elusivum were described from the Botucatu Formation (Leonardi, 1977a; Leonardi, 1980; Leonardi and Godoy, 1980), although never allocated ichnotaxonomically. These footprints, which have been referred to as “theromorphoid” (possible Tritylodontoidea tracks, see Leonardi and Sar- jeant, 1986), are well represented in fossil collections and remarkable specimens are stored at the Paleontology and Stratigraphy Museum, UNESP Campus Rio Claro (S~ao Paulo, Brazil). In this work we examine and describe this material, and propose a new name to identify a specific morphotype. Possible trackmakers are also investigated. Geological setting The Botucatu Formation represents a huge accumula- tion of eolian sandstones, deposited inside a large intra- cratonic basin (Paran�a Basin). In S~ao Paulo State (southeastern Brazil), the Botucatu Formation rests unconformably over the Piramboia Formation, and it is covered by the basaltic lava extrusions of the Serra Geral Formation (Assine et al., 2004). The extension of the Botucatu paleodesert makes it one of the largest in Earth history with an estimated extension of 1.3 millions squared kilometers (Almeida, 1954). It extends over most of the southern portion of Brazil (Goi�as, Mato Grosso, Mato Grosso do Sul, S~ao Paulo, Paran�a, Santa Catarina, Rio Grande do Sul states) and Botucatu lateral equivalents crop out in Uruguay (Tacuaremb�o Forma- tion partim Perea et al., 2009), Paraguay (Misiones For- mation, Leonardi, 1992), and Argentina (Sanford and Lange, 1960; Salamuni and Bigarella, 1967) (Fig. 1). The Twyfelfontein Formation (Namibia) is considered the African portion of the Botucatu paleodesert (Stollhofen, 1999), and the recent finding of possible Brasilichnium footprints in this unit strengthened that correlation (D’Orazi Porchetti and Wagensommer, 2015). CONTACT Simone D’Orazi Porchetti simone.dorazi.porchetti@gmail.com Departamento de Biologia, Faculdade de Filosofia, Ciências e Letras de Ribeir~ao Preto, Universidade de S~ao Paulo, Av. Bandeirantes 3900, 14040–901 Ribeir~ao Preto, SP, Brazil. © 2017 Informa UK Limited, trading as Taylor & Francis Group ICHNOS 2018, VOL. 25, NOS. 2–3, 192–207 https://doi.org/10.1080/10420940.2017.1308929 https://crossmark.crossref.org/dialog/?doi=10.1080/10420940.2017.1308929&domain=pdf&date_stamp=2018-04-21 https://doi.org/10.1080/10420940.2017.1308929 The age of the Botucatu sandstones has been exten- sively discussed in recent decades, with dating that spans from the Late Triassic (Almeida, 1954) to the Early Cretaceous (Scherer, 2000, 2002). This uncer- tainty is due to the lack of unequivocal direct rock dat- ing and to the absence of index fossils. The exclusive, albeit abundant, fossil record of the Botucatu Forma- tion consists of tetrapod traces fossil and, to a lesser extent, invertebrate trace fossil. Based on comparisons with similar ichnofaunas, an age not younger than the Middle Jurassic was proposed (Leonardi and Oliveira, 1990; Bonaparte, 1996) for this lithostratigraphic unit. Other lines of evidence, unrelated to fossils, pushed the presumed age of the Botucatu Formation to the Early Cretaceous (Scherer, 2000, 2002; Tamrat and Ernesto, 2006). This is the age for the Serra Geral Formation, as calculated from isotopic analyses (40Ar/39Ar; Renne et al., 1992; Turner et al., 1994). An age between 134.5 §2.1 and 119.3 §0.95 Ma, has recently been proposed by Br€uckmann et al. (2014) after analysis on U-PB (SHRIMP) data from magmatic zircon crystals. Presence of sand dunes inside the Serra Geral Forma- tion proves that the desert was active at the time of the basalt floods, and therefore, its age could not be much older than the basaltic effusion itself (Scherer, 2000, 2002). Institutional abbreviations CU–MWC: University of Colorado and Museum of Western Colorado joint collection; CU: University of Colorado; MPA: “Material Paleontol�ogico de Arara- quara”; URC (R/M): Museu de Paleontologia e Estrati- grafia “Prof. Dr. Paulo Milton Barbosa Landim”, Instituto de Geocîencias e Cîencias Exatas (IGCE), Universidade Estadual Paulista J�ulio de Mesquita Filho (UNESP), Rio Claro Campus. Materials and methods The material studied here is stored at the Museu de Paleontologia e Estratigrafia “Prof. Dr. Paulo Milton Figure 1. A. The Paran�a Basin (in blue) extends over Brazil, Paraguay, Uruguay, and Argentina. B. Geographic location of Corpedras quarry (red star), and distribution of the Botucatu Formation outcrops (ochre) on the Brazilian territory. C. Simplified stratigraphy of the Paran�a Basin. The age of the Piramboia Formation is controversial (Soares, 1975; Scherer, 2000; Soares et al., 2008). For this reason, it is presented twice, with question marks. Base maps in A) and B) from Creative Commons. ICHNOS 193 Barbosa Landim”, UNESP Campus in Rio Claro City. Hereafter we will refer to it as the “Rio Claro Collection” for brevity. The slabs preserved at the Rio Claro Collec- tion were collected over 13 years (1987–2000) at the S~ao Bento (also known in literature as Corpedras) sandstone quarry in Araraquara Municipality, S~ao Paulo State. Mining activity exploited what possibly were the seasonal or annual boundaries between sets of smaller strata, and many specimens are by–product of such activity. Since 2003 the S~ao Bento Quarry was no longer prospected. Slabs were extracted from sets of cross–strata inclined on average to 26 degrees (Leonardi, 1980). Tracks are impressed either on centimetric (up to 15 cm) packs of grainflow sandstone or on thinner, highly laminated blocks, generated by superimposition of wind ripple strata. Most of the sample probably comes from the basal portion of the slip face of the dune, which is usually not eroded by deflation or superimposition of overcoming dunes, and where the sand avalanches are prominently depositional. The presence of climbing wind ripples is congruent with this interpretation, as the toe of the lee- ward face is the place where inversion of annual domi- nant winds and/or deflected air fluxes usually gives place to this type of deposition (Pye and Tsoar, 2009; Bristow and Mountney, 2013). Eight sandstone slabs yielded “theromorphoid” tracks, mostly organized in short trackways. A total of 41 pes traces, associated to 19 manus traces, have been analyzed first–hand and are described here for the first time. The material is identified by the following collection numbers URCR.70, URCR.110, URCR.111, URCR.112, URCR.115, URCR.138, URCR.142, URCM.41, but these refer only to the footprint-bearing slab. As one slab (URCM.41) yields more than one trackway and different morphotypes, we added here specific letters to identify the sequence of tracks under analysis, in accordance to the illustrations and graphics provided in this work. Tracks are preserved both as concave epirelief and convex hyporelief. All foot- prints have been photographed, reproduced on transpar- ent films, and 3D virtual models of selected specimens have been performed with a close-range photogrammetric approach (see Falkingham, 2012 for details). For our pur- poses, we measured the footprint length at the intersec- tion with the plane of the undisturbed slab surface, also defined as the “zone of negative vertical displacement” (Falkingham, 2016), with the exclusion of the expulsion rims. The ichnological terminology we use here follows Leonardi (1987) and Thulborn (1990). In this article, we adopted a new labelling for the Botucatu Formation slabs, which is specific for the Rio Claro Collection. The new acronyms, URCR and URCM, are adopted here instead of the original one (ARSB) introduced by Giuseppe Leonardi. Correspondence between old and new labelling for the examined material is as fol- lows, ARSB.200 D URCR.70; ARSB.262 D URCR.110; ARSB.257 D URCR.111; ARSB.256 D URCR.112; ARSB.285 D URCR.115; ARSB.258 D URCR.138; ARSB.288 D URCR.142; ARSB.244 D URCM.41. Systematic ichnology Ichnogenus Brasilichnium (Leonardi, 1981) Emended diagnosis: Quadrupedal trackways, with neat heteropody. Tetradactyl manus print, digitigrade, usually three- to two-digit marks are preserved, isolated from each other. Tetradactyl pes prints, with average length/ width ratio around 0.7. Pes digit marks are short, and usually separated from the metapodial marks; drop-like, proximally rounded, and distally pointed, to elliptical pes digit marks. Pes digit marks II and III the largest, digit III dominant in terms of length. Digit mark IV usually stout, distally blunt. Manus and pes digit marks formed by single pad. Palm print rounded, wider than long, anteriorly and posteriorly convex. No tail mark. Type ichnospecies Brasilichnium elusivum (Leonardi, 1981) Brasilichnium anaiti isp. nov. Figs. 2 and 3 Etymology: Anait�ı means large in the native Brazil- ian Tup�ı–Guaran�ı language. This name refers to the larger size of this form compared to Brasilichnium elusivum. Holotype: URCR.70, a sequence of 11 pes and 12 manus prints. Footprints preserved as concave epirelief. Paratype series: URCR.110: the slab is broken in 9 pieces, and now recomposed inside a wooden box; six footprints are preserved as concave epirelief, the first is incomplete proximally; three hand prints are associated to pes traces 1, 3, and 5. URCR.111: Slab with a sequence of four footprints; two partial handprints are associated to pes traces 1 and 3; the first pes trace is only partially preserved, and the pertaining expulsion rim is preserved on URCR.110. This trackway is actually the prosecution of that on URCR.110, as the two slabs were originally a single, larger one (URCR.110 C URCM.111 have in total 10 footprints and 5 handprints). Tracks preserved as con- cave epirelief. URCR.112: Three pes prints in sequence, associated to three very shallow hand prints; the manus print associ- ated to footstep number 2 shows two small round marks at the tip of a shallow depression. Tracks preserved as concave epirelief. URCR.115: Four footmarks and one handprint, in a single trackway. Tracks preserved as convex hyporelief. 194 S. D’ORAZI PORCHETTI ET AL. URCM.41: Large slab with at least five large foot- prints, organized in a trackway (trackway A); no hand prints pertaining to this trackway are visible (other track- way and isolated footprints are present on this slab but pertains to Brasilichnium elusivum). Referred material: 1980 “pistas Teromorf�oides,” fig. 2A–2B, p. 3085, Leo- nardi and Godoy. 1980 “pistas teromorf�oides,” figs. 5A–D, p. 3088, Leo- nardi and Godoy. 1986 “A theromorphoid trackway from the pave- ments of S~ao Carlos,” fig. 7, p. 80, Leonardi and Sarjeant. 1990 “Theromorphoid footprints from Botucatu For- mation,” plate XI A–E, p. 224. Leonardi and Oliveira. Figure 2. Holotype slab URCR.70 (left), and relative drawing (right). Footprints are numbered in sequence, from the bottom to the top of the figure. Handprints are marked with the same number of the associated footprints followed by the letter a (i.e., URCR.70–1a). ICHNOS 195 1999 “Pegadas teromorf�oides atribu�ıdas �a ?Tritylodontoidea,” fig. 2A–C, p. 44, Leonardi and Carvalho. 2007 “Theromorphoid footprint attributed to relative bigger mammals,” fig. 3A–C, p. 384, Leonardi, Carvalho, and Fernandes. Repository: Museu de Paleontologia e Estratigrafia Prof. Dr. Paulo Milton Barbosa Landim, Instituto de Geocîencias e Ciências Exatas (IGCE), Universidade Estadual Paulista J�ulio de Mesquita Filho (UNESP), Rio Claro Campus, S~ao Paulo State (Brazil). Figure 3. Paratype series with slabs A. URCR.111, B. URCR.115, C. URCM.41, D. URCR.110, and E. URCR.112. On URCM.41 B. anaiti is in black, whereas B. elusivum trackways are represented in grey. Halftones cover eroded portions of the footprints. Scale bar 10 cm. 196 S. D’ORAZI PORCHETTI ET AL. Type Locality and Horizons: Corpedras sandstone quarry, Araraquara Municipality, S~ao Paulo State, Brazil. Botucatu Formation. Distribution: ?Middle Jurassic–Early Cretaceous of Brazil. Ichnospecific diagnosis: Quadrupedal trackway, with neat heteropody, pes print larger than manus print; tetradactyl, paraxonic-to-slightly ectaxonic pes print; foot digit marks are short, usually separated from metapodials by a stenosis or groove (especially Figure 5. Detail of manus prints. A. URCR.110–1a. B. URCR.70–0a. Black arrows show single digit marks. Only two digit marks are pre- served in A), possibly corresponding to the lateral ones of B), where three digit marks are visible. Difference in colour tones between A) and B) is partly due to different light conditions during photo shooting. Scale bar 2 cm. Figure 4. Three-dimensional model of A. URCR.70–1 and B. URCR.70–2, obtained from modelling clay cast of the original footprints. Black arrows to show the stenosis at the base of the central digits, effect of the digital arcade in trackmaker’s acropodium. Close-up views of C. URCR.70–1, D. URCR.70–3, E. URCR.70–5, and F. URCR.70–7. Trackway midline to the right of each footprint. Scale bar 5 cm. ICHNOS 197 on the centrals two digits), giving the footmark a paw–like appearance. First and fourth pes digit marks distally blunt, whereas the second and third appear distally sharp. Digit marks I–III are more deeply impressed compared to the lateral one, with the deep- est area corresponding to the metatarsal–phalangeal joints. Pes print wider than long, with an average FL/ FW ratio of 0.72. Manus print with at least three digit marks, always preceding the footmarks. No tail marks have been observed. Typically found on the foreset of sand dunes in hyperarid environments, usually in association with Brasilichnium elusivum. The new ichnospecies differs from Brasilichnium elu- sivum for the following characters: digit marks II and III Table 1. From left to right, (Rep. N�): repository numbers. (N� of pes traces): number of pes marks for each trackway. (N� of manus traces): number of manus traces in the trackway. (Trackway Length): length of the trackway (mm). (Trackway Width): maxi- mum external width of the trackway (mm). Asterisk for the holo- type (URCR.70). Rep. No. No. of Pes Traces No. of Manus Traces Trackway Length Trackway Width URCM.41 5 n/a 58 15 URCR.70� 11 12 96 15 URCR.110 7 2 59 12.5 URCR.111 4 2 45 13 URCR.112 3 2 29 15 URCR.115 4 1 36 17 URCR.138 2 n/a n/a n/a URCR.142 5 n/a n/a n/a Table 2. From left to right, (Rep. N�): repository numbers. (Trackway): when necessary (i.e., multiple trackways on the same slab), each trackway is labelled with a letter (e.g., URCM.41–A). (Footprint N�): number of pes mark in the trackway. (Foot L): pes length, and (Foot W): width (mm). (Digits Y/N): presence (yes: Y) or absence (not: N) of digit marks on the footprint. (N� of digit –Pes): number of visible digit marks on the foot mark. (Pes Rotation): orientation of the longitudinal axis of the pes respect to the trackway midline; rotation is expressed in qualitative terms: 0 (zero) D no rotation, 1 (one) D inward rotation of pes. (Handprint –Y/N): presence (Y) or absence (N) of the handmark on a given step. (Manus L): manus length and (Manus W) width in mm. (N� of digits –Manus): number of visible digit marks on the handprint. Asterisk for the holotype (URCR.70). Rep. No. Trackway Footprint No. Foot L Foot W Digits (Y/N) No. of digit (Pes) Pes Rotation Handprint (Y/N) Manus L Manus W No. of digits (Manus) URCM.41 A 1 44 n/a N n/a n/a N n/a n/a n/a 2 34 57 N n/a n/a N n/a n/a n/a 3 39 57 N n/a n/a N n/a n/a n/a 4 33 54 N n/a n/a N n/a n/a n/a 5 44 59 Y 4 n/a N n/a n/a n/a URCR.70� n/a 0 n/a n/a n/a n/a n/a Y n/a 28 2 1 46 62 Y 4 0 Y n/a 16 2 2 42 60 Y 4 1 Y n/a 25 2 3 46 62 Y 4 0 Y n/a 20 2 4 41 60 Y 4 1 Y n/a 28 2 5 42 59 Y 4 0 Y n/a 22 2 6 41 60 Y 4 1 Y n/a 23 2 7 43 59 Y 4 0 Y n/a 12 2 8 40 56 Y 4 1 Y n/a 24 2 9 40 57 Y 4 0 Y n/a 17 2 10 41 60 Y 4 1 Y n/a n/a 2 11 43 58 Y 4 0 Y n/a 28 2 URCR.110 n/a 1 n/a 63 Y 4 1 N n/a n/a n/a 2 47 63 Y 4 1 N n/a n/a n/a 3 49 60 Y 4 1 Y n/a n/a 2 4 48 58 Y 4 1 N n/a n/a n/a 5 45 61 Y 4 1 Y n/a n/a 2 6 47 62 Y 4 1 N n/a n/a n/a 7 n/a n/a n/a n/a n/a n/a n/a n/a n/a URCR.111 n/a 1 46 64 Y 4 1 Y 8 23 2 2 47 58 Y 4 1 N n/a n/a n/a 3 42 64 Y 4 1 Y 8 23 2 4 40 56 Y 4 1 N n/a n/a n/a URCR.112 n/a 1 45 68 N n/a n/a Y n/a n/a n/a 2 44 67 N n/a n/a N n/a n/a n/a 3 47 61 N n/a n/a Y n/a n/a n/a URCR.115 n/a 1 43 n/a N n/a 1 N n/a n/a n/a 2 58 70 N n/a 0 Y 10 24 ?3 3 47 68 N n/a 1 N n/a n/a n/a 4 61 73 N n/a 0 N n/a n/a n/a URCR.138 n/a 1 43 61 N n/a n/a N n/a n/a n/a 2 43 69 N n/a n/a N n/a n/a n/a URCR.142 n/a 1 56 n/a N n/a n/a N n/a n/a n/a 2 43 59 N n/a n/a N n/a n/a n/a 3 49 62 N n/a n/a Y n/a n/a n/a 4 45 72 N n/a n/a N n/a n/a n/a 5 n/a n/a N n/a n/a N n/a n/a n/a 198 S. D’ORAZI PORCHETTI ET AL. are functionally dominant for load bearing in B. anaiti, respect to those in B. elusivum. The overall pes shape is more symmetrical in B. anaiti than in B. elusivum, with a coarse bilateral symmetry respect to a plane passing between digit marks II and III. Central digit marks in B. anaiti commonly show divergent distal ends. In B. elusi- vum digit marks I–III are usually iso-oriented. Pes digit mark in B. anaiti are more neatly isolated from the sole mark than in B. elusivum, with a drop-like shape of cen- tral digit mark II and III. The average size of B. anaiti is four times bigger than that of B. elusivum. Description: All slabs at the Rio Claro Collection preserve trackways of animals moving uphill, in walk- ing gait. The direction of the trackways is inferred from the relative orientation of the expulsion rims and digit marks. Five out of eight trails are preserved as concave epirelief (URCR.70; URCR.110; URCR.111; URCR.112; URCR.138), the remaining three track- ways are preserved as convex hyporelief (URCR.115; URCR.142; URCM.41). When preserved, all pes prints show four digit marks. There is no unequivocal way to refer these digit marks to trackmaker’s acropodials (digits I, II, III, and IV, or digits II, III, IV, and V, alternatively). The general shape of the footmark is symmetric, although digit mark I is appar- ently shorter than digit mark IV. Digit marks II and III are usually the best preserved in the series, and have approximately the same length. Digit mark IV is stouter than the others (Fig. 4). The sole mark mostly represents the metatarsal-phalangeal portion of the autopodium region, and is the portion of maximum penetration of the pes into the substrate, anteriorly; it fades rapidly into the anterior wall of the expulsion rim, posteriorly. The sole mark is roughly elliptical, wider than long. The longitudinal axis of the pes is frequently rotated inward, so that the lateral digit mark extends far anterior to the tip of the medial digit. Digit marks may appear straight or, in several cases, outward oriented. This latter case seems related to the recurrent rotation of the autopo- dium during the walk cycle. Footprints are usually shal- low, but deeper traces are occasionally preserved. Tracks of one side of the trail may be rotated to a different degree in relation to the controlateral series, so that the trackway results asymmetric relative to the midline. Manus prints are relatively rare, except on URCR.70, where manus prints outnumber pes prints. Hand traces are typically shallower than those of the foot, and their preser- vation is usually worse, to the point that is difficult to define a clear pattern. It is common to find two to three faint marks left by hand digits (Fig. 5). It is unclear if the faint- ness of the hand prints is the effect of a digitigrade posture or a taphonomic bias, but we tend to support the latter Table 3. From left to right, (Rep. N�): repository numbers. (Trackway): when necessary (i.e., multiple trackways on the same slab), each trackway is labelled with a letter (e.g., URCM.41–A). (Pes Pace): number of pes pace and measure (mm). (Pes Stride): stride and relative measure (mm). (Pes Triplet): in this column, the triplet of footprints is reported on which pace angulation has been measured (in degrees). The same measurements are repeated for the handprints from ninth column on. Rep. No. Trackway Pes Pace mm Pes Stride mm Pes triplet degrees Manus Pace mm Manus Stride mm Manus triplet degrees Pes-Manus Distance Mm URCM.41 A 1_2 170 1_3 265 123 119 n n n n n n n n 2_3 140 2_4 271 234 123 n n n n n n n n 3_4 175 3_5 264 345 122 n n n n n n n n 4_5 128 n n n n n n n n n n n n URCR.70� n/a 1_2 126 1_3 172 123 102 0_1 123 0_2 173 zero12 85 1_1a 32 2_3 95 2_4 175 234 104 1_2 134 1_3 171 123 82 2_2a 13 3_4 127 3_5 173 345 103 2_3 126 2_4 174 234 83 3_3a 22 4_5 93 4_6 168 456 101 3_4 135 3_5 172 345 82 4_4a 11 5_6 125 5_7 167 567 102 4_5 130 4_6 174 456 81 5_5a 39 6_7 89 6_8 171 678 105 5_6 133 5_7 171 567 82 6_6a 35 7_8 126 7_9 171 789 104 6_7 122 6_8 164 678 79 7_7a 41 8_9 90 8_10 160 8910 102 7_8 136 7_9 171 789 80 8_8a 24 9_10 115 9_11 170 91011 109 8_9 130 8_10 165 8910 79 9_9a 44 10_11 95 n n n n 9_10 132 9_11 161 91011 74 10_10a 23 URCR.110 n/a 1_2 105 1_3 188 123 120 0_1 n 0_2 190 n n n n 2_3 111 2_4 184 234 115 1_2 n 1_3 194 n n n n 3_4 107 3_5 189 345 114 2_3 n 2_4 n n n n n 4_5 117 4_6 192 456 115 3_4 n 3_5 n n n n n 5_6 111 n n n n n n n n n n n n URCR.111 n/a 1_2 107 1_3 188 123 116 n n 0_2 190 n n 1_1a 30 2_3 114 2_4 189 234 123 n n n n n n 2_2a 32 3_4 102 3_5 n n n n n n n n n n n URCR.112 n/a 1_2 148 1_3 237 123 117 1_2 156 1_3 237 123 102 1_1a 42 2_3 128 n n n n 2_3 130 n n n n 2_2a 47 3_4 n n n n n n n n n n n 3_3a 35 URCR.115 n/a 1_2 116 1_3 211 123 110 n n n n n n 1_1a 23 2_3 141 2_4 226 234 117 n n n n n n n n 3_4 123 n n n n n n n n n n n n ICHNOS 199 explanation (see below). From a quantitative point of view, the footprint length (FL) has a mean value of 44.58 mm, whereas the mean for foot width (FW) is 61.64 mm. The mode for FW is 60 mm. Manus traces have an average length of 8.67 mm for a width of 22.35 mm. Trackways show an average foot stride of 196.71 mm, whereas pes pace angulation is 111.57 degrees on average.Manus stride is 179 mm on average, for a pace angulation mean value of 82.63 degrees.Manus–pes distance is 31.35 mm on average. Trackway width has an average value of 145.8 mm. A complete dataset of measurements is seen in Tables 1–3. When indexed to the average width of the pes, which is the most consistent linear measurement, we find that the trackway width is 2.36 times the foot width; stride/pes width ratio is 3.19. Discussion and remarks Fernandes and Carvalho (2008) redefined to four the number of digit marks on the pes of Brasilichnium elusi- vum. This shows that the material under examination and B. elusivum share a similar basic pedal structure. The analysis of specimens of B. elusivum at the Rio Claro collection (D’Orazi Porchetti et al., 2016) reveals more shared features with B. anaiti. Based on the examined sample, the FL/FW ratio of Brasilichnium anaiti is 0.72 (FL n D 38, FW n D 36), a value remarkably similar to that of B. elusivum (FL/FW ratio D 0.69), as calculated on best preserved tracks (FL n D 313; FW n D 351) from a total sample of 420 pes prints of B. elusivum in walking gait. At the same time, a comparison of the mean values of foot width between B. elusivum and B. anaiti reveals a clear dimensional gap (Fig. 6). The mode for the FW value of B. elusivum (based on the Rio Claro sample) is 15 mm, compared to a 60 mm value in B. anaiti. In addition, the mini- mum value of foot width in B. anaiti is 54 mm, for a maximum of 73 mm, whereas the maximum value mea- sured for B. elusivum, in the Rio Claro collection, is 30 mm (minimum D 8 mm). Accordingly, there is no overlapping between the footprint sizes of small and large Brasilichnium, even at the extremes of their dimensional distribution, and the comparison between the modes of FW values for B. elusivum and B. anaiti (15 mm vs. 60 mm) definitively split these two forms apart from one another. The adoption of a new ichnotaxonomic label, espe- cially at the ichnospecies rank, is particularly prone to the author’s view in naming practices. Recommendation in the adoption of ichnotaxobases (see Bertling, 2007; Bertling et al., 2006), suggest to avoid size as a diagnostic feature. However, when associated to other morphologic features, as with the material under examination, size might give helpful insights. Differences in morphology, associated to the neat dimensional gap between these two morphotypes, and the variable locomotion styles of Brasilichnium elusivum (see D’Orazi Porchetti et al., 2017), in contrast to the single walking gait observed in B. anaiti, justify a separation at least at the ichnospecific level (Fig. 7). Relative abundance has been calculated on the slab sample of the Rio Claro Collection. On a total of 109 slabs, eight yielded material ascribable to the new ichno- taxon. In terms of number of trackways, the comparison Figure 6. Frequency distribution as plotted from the Rio Claro dataset. Footprint width (FW) on the X axis (in mm); number of individu- als on the Y axis. From left to right, Brasilichnium elusivum (n D 351) and B. anaiti (n D 36). Difference in height is due to the high num- ber of individuals for B. elusivum in the sample respect to those of B. anaiti. Note the clear dimensional gap between the two groups. 200 S. D’ORAZI PORCHETTI ET AL. Figure 7. Selected specimens from the Rio Claro Collection, reproduced here in order to show foot morphology and gaits of Brasilich- nium elusivum. A. Three-dimensional model of a single footprint from slab URCM.41, to show details of the pes morphology of Brasilich- nium elusivum. Original track preserved as convex hyporelief. Track width 2 cm. B. Photograph and drawing of slab URCM.34; slab with well-preserved trackways in walking gait with manus prints; scale bar 10 cm. Drawing at the same scale of the photograph. All footprints preserved as convex hyporelief. C. Brasilichnium elusivum, photograph and drawing of slab URCR.23, with three consecutive manus–pes sets in half-bounding gait, preserved as convex hyporelief. The trackway is heading to the top of the image. Pes prints are incomplete, partially lost at their top (shaded gray). Scale bar 10 cm. D. Photograph and drawing of slab URCM.52 with B. elusivum trackway in skip- ping gait (on the left side of the slab). Scale bar 10 cm. Drawing at the same scale of the photograph. All tracks preserved as concave epirelief. E. Photograph and drawing of slab URCM.113 with downhill-oriented trackway of B. elusivum. The trackmaker was moving from the top to the bottom of the slab. Scale bar 10 cm. Drawing at the same scale of the photograph; footprints preserved as convex hyporelief. ICHNOS 201 of B. elusivum/B. anaiti reveals a ratio of 89 to 8, the larger quadrupedal traces being a tenth in number of those of B. elusivum, and 7.3% on the total number of slabs containing either of the morphotypes. Large and small Brasilichnium forms should not be regarded as the expression of the same trackmaker population not only because there is a discontinuity in size distribution, but also because B. elusivum shows an array of gaits which is unknown for B. anaiti. As all the Botucatu ichnites are preserved on the fore- set of sand dunes, they were all imprinted on inclined surfaces. Leonardi (1980) reported an average value, from measurements on 58 dune foresets, of 26 degrees (lowest D 12�; highest D 32�). Aside from other tapho- nomic aspects, an important feature, always associated with the foot mark, is an expulsion rim, which constantly rests on the downhill side of the track. Direct and indi- rect track features (sensu Gatesy, 2003) are sometimes so intimately associated to one another that is somewhat artificial to treat them separately. Yet marginal ridges bear no clear signs of the foot anatomy, but helps under- standing how load forces acted on the sediment. All the Rio Claro specimens have pressure pads, typically showing sediment displacement in a thrust- like fashion. These pressure pads are also asymmetric, when observed from behind. The medial portion is always shallower than the lateral one. If associated with the outward orientation of the pes digits, all these features can be explained as the effect of an inward rotation of the foot during the step cycle (D’Orazi Porchetti et al., 2014). Another matter of discussion is whether the Botucatu tracks can be considered as surficial marks or the result of foot/sediment interaction at some depth below the surface. As remarkably shown by Loope (2006), tracks can be preserved even on dry sand, at a relative depth below the sediment/air interface. Several features on the Rio Claro footprints points to a subsurficial origin, and the preservational style of the hand prints might help explaining this point. As stated above, handprints are typically less well–preserved than pes prints in terms of anatomical completeness (preservation of only the distal portions of the digits) and quantity (manus traces pres- ent only on one side of the trackway or totally absent). The combined action of the inclined surface, which moves weight vectors back onto the rear legs, and possi- bly the biomechanics of the trackmakers (weight distri- bution on the forearms), allowed for a reduced penetration of the hand into the sediment (Seilacher, 2007). Accordingly the final contact of the pes and the manus happened at different depth into the sand on the lee side of the dunes. This explains why only the distal, digital portion of the hand is usually preserved. Thus the possibility to observe a clear hand mark in association with the footprint is usually hampered. Yet, it is not absolutely clear that all these traces are deep prints. As a consequence, there is no unambiguous way to state a clear dimensional ratio between the hand and the foot marks. Trackmaker attribution Previous works on the quadrupedal morphotypes of the Botucatu Formation relied on the presumed age of this lithostratigraphic unit to evaluate potential trackmakers. As a consequence, shift in dating affected the attribution. For instance, Leonardi et al. (2007) stated, in a recent reappraisal of the Botucatu ichnofauna, that the “thero- morphoid” tracks might have been made by undeter- mined true mammals, on the basis of a reassessment of the age of the Botucatu Formation (Scherer, 2000; 2002). The process of trackmaker attribution should otherwise exclusively rely on features that are unequivocal expres- sions of trackmaker’s morphological characters. Obvi- ously, this approach has its own clear limits, as useful characters (i.e., synapomorphies) are rarely found in footprints. In the original interpretation of Leonardi, the pro- ducer of the footprints discussed here was something dif- ferent from that of Brasilichnium elusivum, for two reasons. In his understanding (Leonardi, 1980; Leonardi and Sarjeant, 1986), B. elusivum was pentadactyl and B. anaiti was too large for a Mesozoic mammal. However relatively large mammals are known today from the Early Cretaceous of China (i.e., Repenomamus giganticus Hu et al., 2005). The phalangeal formula proposed by Leonardi (1981) for Brasilichnium elusivum (2–3–3–3–3) cannot be tested on the sampled footprints, as digit marks show only one pad. The number of four digit marks in the pes of B. anaiti is not indicative for any specific group, given that different lineages, other than synapsids, such as crocody- lomorphs, have forms with tetradactyl feet. Yet, Brasilichnium anaiti shows a discontinuity, which appears as a hiatus or a stenosis, in the proximal part of the phalangeal portion of the foot, best visible on the central couple of digit marks. This structure is seen in the form of a crease or groove, depending on the style of footprint preservation (concave epirelief or convex hyporelief), separating the sole print from digit marks. This feature can be useful for the attribution of B. anaiti as it is related to the configuration and posture of the acropodium. This mark is well explained by the presence of a digital arcade (K€ummel and Frey, 2012, 2014) in the foot, an arrangement that does not allow all phalanges to touch the sediment at the same level. In this acropodial 202 S. D’ORAZI PORCHETTI ET AL. configuration, digits are held bent in the sagittal plane during most part of the walking cycle. K€ummel and Frey (2012) first presented evidence of a digital arcade in footprints of purported synapsid origin. Among others, a specimen of Brasilichnium elusivum is figured in K€ummel and Frey (2012, fig. 17f, from Lockley and Hunt 1995, fig. 4.22). As noted by K€ummel and Frey (2012, 2014), a digital arcade is present in most extant mammals as it was in most Therapsida, including Meso- zoic Mammaliamorpha. Accordingly, we here adopt this feature as robust evidence for the mammaliamorph the- rapsid origin of B. anaiti. A more comprehensive discussion about the track- makers attribution of Brasilichnium anaiti is extremely problematic. Direct comparison with body fossils from similar environments, and comparable age, are ham- pered by the rarity of skeletal specimens preserving com- plete autopodia. If the temporal range of large and small Brasilichnium is considered as a whole, with a Late Trias- sic FAD from the Redonda Formation (Lucas et al., 2010) and an Early Cretaceous LAD from the Botucatu Formation (according to age attribution of Scherer 2000, 2002), a time span of approximately 75 MY (Rethian– Valanginian) is found. During this period, Brasilichnium had its acme in the Early Jurassic of the Navajo Sand- stone (and equivalents) and in the Brazilian Botucatu Formation. In Brasilichnium, trackmaker’s foot morphology appears to be stable over a long period of time, as is the locomotion styles, and the association with a specific environmental setting. This might be interpreted as a true biological signal, or might depend on major misun- derstandings of the age of the footprint–bearing lithos- tratigraphic units (particularly the Botucatu Formation). A comparison based on the time range of Brasilichnium, and that of Mesozoic therapsids, shows that potential trackmakers might belong either to non-mammalian mammaliamorphs, or to early mammals. So far, no definitive feature observed on B. anaiti can help discrim- inate between these two groups. Comparison with similar ichnomorphs Large Brasilichnium are relatively rare worldwide, if compared to the smaller forms, commonly labeled as Brasilichnium elusivum. Materials that could potentially be referred to as Brasilichnium anaiti comes from the Nugget Sandstone (Early Jurassic) Idaho, USA, as the specimen (CU 179.122) figured in Lockley et al. (2011, fig. 5B). Lockley and Hunt (1995) figured another speci- men (CU–MWC 183.6) that bears strong similarities with the Brazilian material. Ellenberger (1970, 1972, 1974, 1975) erected several ichnotaxa on material from the Elliot and Clarens formations of Lesotho. Problems related to Ellenberger’s approach to ichnotaxonomy have been highlighted in previous works (Olsen and Gal- ton, 1984; Lockley et al., 2004; Rainforth, 2003; D’Orazi Porchetti and Nicosia, 2007), and many ichnotaxa of purported synapsid origin, proposed by Ellenberger, are nomina nuda. On the other hand, Ellenberger’s work gives us a glimpse on the ichnological richness of the Stormberg Group of Lesotho. Aside from stating the impelling need for revising the original material on its stratigraphic con- text, we can here attempt to identify the forms that bear closer similarities with Brasilichnium. Among them, ichnites with tetradactyl pes prints, from the B/1 zone of Ellenberger biostratigraphic framework, have been infor- mally labeled as “Eotetrapodiscid�es.” Two ichnospecies, Eotetrapodiscus cursor and Eotetrapodiscus moyenensis, might be compared to the Brazilian material. E. cursor is apparently closer in size to the dimensional range of Bra- silichnium anaiti. On the other hand, E. moyenensis is well beyond the size range of that ichnospecies. Chelichnus is a Permian ichnogenus with four ichno- species from North America and Europe (McKeever and Haubold, 1996), which bears coarse similarities with Bra- silichnium. On the other hand, it is diagnosed as a penta- dactyl (manus and pes) ichnotaxon, and therefore with a basic difference relative to Brasilichnium. A general overview of possible synapsid tracks from similar environments should also take Navahopus into account, a quadrupedal ichnotaxon with two ichnospe- cies: N. falcipollex Baird (1980), and N. coyoteensis (Milan, Loope, and Bromley, 2008), both from the Lower Jurassic Navajo Sandstone of the United States. Lockley and Hunt (1995) discussed extensively on the subject, noting the similarity between Navahopus and Brasilich- nium. Lockley et al. (1994) first proposed a synapsid ori- gin for N. falcipollex. Hunt and Lucas (2006) reevaluated its holotype (MNAV 3430), pointing out incongruences in the composite outline proposed by Baird (1980). Dis- cussing the ichnotaxonomic status of Navahopus is beyond the scope of the present paper, but Brasilichnium and Navahopus share important features, which points to a similar trackmaker. Footmarks of both forms have four digit marks, which are separated from the plantar portion of the footprints by a sand crease. This feature is here considered the result of the posture (digital arcade) of the trackmaker foot, which according to K€ummel and Frey (2012, 2014), indicate a therapsid origin. This simi- larity is of interest for the ichnological characterization of hyperarid environments, dominated by erg facies, and consequently for the Brasilichnium ichnocoenosis (Hunt and Lucas, 2007), especially under the paleozoological respects (see below). ICHNOS 203 Overview on the Botucatu ichnofaunal composition Leonardi and Oliveira (1990) first investigated the faunal composition of the Botucatu Formation on a quantitative basis. On a sample of 100 slabs (for a total count of 104 “individuals”) from the Ouro site (slab ARSB–5 to slab ARSB–149; Leonardi and Oli- veira, 1990, p. 227), they obtained the following per- centages in terms of individual occurrences: mammaloid D 64.4%, dinosauroid D 27.9%, thero- morphoid D 7.7%. Our analysis is based on 109 slabs from the same locality. Of those, eight slabs (7.3%) yielded theromorphoid (i.e., Brasilichnium anaiti) tracks. Mammaloids are represented on 61.5% of the slabs, and dinosauroids on 20.2%. When the same sample is investigated for relative presence of individ- uals (to say, how many trackways of one form are present in the sample), we found that of the 154 rec- ognized trackways, 90 are mammaloid (58.4%), 22 dinosauroid (14.3%), and 8 theromorphoid (5.2%). We considered 34 trackways as indeterminate, which rep- resent 22.1% of the sample. Our results do not exactly match those of Leonardi and Oliveira (1990), although there are some similarities. The high per- centage of forms that we do not ascribe to any cate- gory might influence the results, but the percentage of theromorphoid seems quite stable across the analy- ses. The Botucatu vertebrate ichnites composition also approaches that published by Reynolds (2006; Rey- nolds and Weasma, 2002) for the early Middle Juras- sic Aztec Sandstone (but see Hunt and Lucas, 2006, for alternative dating of this lithostratigrphic unit), which has up to 70% of quadruped tracks and 30% of biped tracks. Similarly, Rainforth’s (1997) report on the ichnofauna composition of the dunes foreset of the Navajo Sandstone shows that about 60% of the ichnotaxa can be ascribed to synapsid trackmakers, the remaining being of dinosaurian origin. Aside from vertebrate tracks, the Botucatu slabs yielded an array of invertebrate ichnofossils. Leonardi (1980) first noticed the presence of worm and arthropod trails and burrows. A detailed study on the invertebrate ichnofauna of the Botucatu Formation (Fernandes et al., 1990) identified Taenidium satanassi and T. serpenti- num, besides generic “U-shaped” burrows. The Rio Claro Collection includes invertebrate traces, as Planolites isp., Arenicolites isp., and at least one portion of arthropod trail (Plate II, slab URCR.138). These come from similar hyperarid depositional environments. On the other hand, the ichnological composition of the Botucatu For- mation, as recorded from extensive sample of the Ouro site, is limited to dune foresets. So far, there is no inter- dune sampling, what may explain the abundance of relatively small tracks (< 10 centimeters in width), com- pared to the exiguous record of large forms, such as the alleged ornithopod tracks (MPA–334 and MPA–337 series I–V) described by Fernandes and Carvalho (2007), and some undetermined large tridactyl footprints (e.g., slab URCR.143) in the Rio Claro Collection. Even if the validity of the land-vertebrate ichnofacies has been considered as problematic (Santi and Nicosia, 2008) or even refused (MacEachern et al., 2012), the attempt to formalize the recurrence of typical land-vertebrate foot- prints in specific depositional environments has a history, and should not be overlooked. Depending on the approach to the problem, the Octopodichnus–Entradichnus ichnofa- cies (Buatois and Mang�ano, 2011) might be considered the most inclusive name to adopt in this case, with its parallel in the land-vertebrate ichnofacies represented by the Brasi- lichnium ichnocoenosis of the Chelichnus ichnofacies (Hunt and Lucas, 2007). In this regard, Hunt and Lucas (2007 and references therein) pointed out how the approach of vertebrate ichnologists to ichnofacies is more biotaxonomic than ethological. Before downgrading or dis- missing land-vertebrate ichnofacies it would be important to evaluate ecologic aspects which are inherent to the recur- rent association of specific ichnites and depositional envi- ronments, as in the case of Brasilichnium and paleoergs. In this respect, the basic approach is a strict process of defini- tion based on the ichnotaxonomic composition. Formaliza- tion of a characteristic element of the Brasilichnium ichnocoenosis goes in this direction. Conclusions The Botucatu Formation slabs investigated in the present article revealed a distinct track morphotype, whose iden- tity is substantiated by quantitative and qualitative data. For this reasons a new ichnospecies, Brasilichnium anaiti, is proposed to encompass this form. This new ichnotaxon is a useful tool in the frame of the ichnofacies approach to vertebrate ichnology, especially for the Bra- silichnium ichnocoenosis of the Chelichnus ichnofacies (Hunt and Lucas, 2007), as it commonly appear associ- ated to B. elusivum on the foreset of Mesozoic sand dunes. In percentage, dune foreset ichnocoenosis shows a constant ratio between therapsid and dinosaurian trackmakers, with a majority of the former group (rela- tive abundance between 60 and 70%). The trackmaker of Brasilichnium anaiti is either a non-mammalian mammaliamorph, or an early mammal. Hyperarid facies, and specifically foresets of ancient sand dunes, shows a positive correlation with Mesozoic synap- sid tracks, which are particularly abundant in this setting and shows a neat dimensional disparity, from very small to relatively large forms. 204 S. D’ORAZI PORCHETTI ET AL. Acknowledgments This work is intended as a contribution for the project “Dune’s Life: the Track Record of a Mesozoic Warm Desert.” The Uni- versity of S~ao Paulo, at Ribeir~ao Preto, is acknowledged for support and logistics. We are indebted to Lilia Maria Dietrich Bertini for constant help and assistance. Cibele Gasparelo Vol- tani is kindly acknowledged for logistic support during collec- tion analysis. We wish to thank Ignacio D�ıaz-Mart�ınez (Universidad Nacional de R�ıo Negro (Argentina) and an anon- ymous reviewer for helpful comments to the original manu- script. Lorenzo Marchetti (Universit�a degli Studi di Padova) is acknowledged for further review. We would like to thank Hen- drik Klein (Saurierwelt Pal€aontologisches Museum, Neumarkt) for constant editorial assistance. Funding S. D’Orazi Porchetti’s research was supported by a Fundaç~ao de Amparo �a Pesquisa do Estado de S~ao Paulo (FAPESP) Post–Doctoral Grant (Process Number 2013/01930–1). ORCID Max C. 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