Actinistian gular plates from the Cretaceous of Mexico and the problems assigning gular plates taxonomically

Abstract

Two gular plates of an indeterminate actinistian are described from the Cretaceous of Muhi quarry, Hidalgo state, in central Mexico. Their narrow shape belongs to the few actinistian gular plates with a high length-/-width ratio (above 4) in contrast to most known actinistian gular plates with a length-/-width ratio below 4. The gulars of Muhi quarry are assigned, with caution, to the actinistian family Mawsoniidae on the basis of the length-/-width ratio (around 4.5) of the gular, which can be found in three other genera of the family. There are not enough characteristics in actinistian gular plates alone to erect a new genus or species. Noteworthy is the large size of the Muhi gulars that corresponds to a body length of about 1.6-m - the length of <i>Latimeria</i> today. The gulars are preserved in association with a basibranchial tooth plate and a few neural spines. This is the third actinistian record from the Cretaceous of Mexico.

Foss. Rec., 19, 101117, 2016 www.foss-rec.net/19/101/2016/ doi:10.5194/fr-19-101-2016 Author(s) 2016. CC Attribution 3.0 License.

Hans-Peter Schultze1 and Katia Adriana Gonzlez-Rodrguez2

1University of Kansas, Natural History Museum and Biodiversity Institute, Lawrence, Kansas, USA

2Instituto de Ciencias Bsicas e Ingeniera, Museo de Paleontologa, Centro de Investigaciones Biolgicas, Universidad Autnoma del Estado de Hidalgo, Mineral de la Reforma, Hidalgo, Mexico

Correspondence to: Hans-Peter Schultze ([email protected])

Received: 7 January 2016 Revised: 22 February 2016 Accepted: 3 March 2016 Published: 15 April 2016

Abstract. Two gular plates of an indeterminate actinistian are described from the Cretaceous of Muhi quarry, Hidalgo state, in central Mexico. Their narrow shape belongs to the few actinistian gular plates with a high length / width ratio (above 4) in contrast to most known actinistian gular plates with a length / width ratio below 4. The gulars of Muhi quarry are assigned, with caution, to the actinistian family Mawsoniidae on the basis of the length / width ratio (around 4.5) of the gular, which can be found in three other genera of the family. There are not enough characteristics in actinistian gular plates alone to erect a new genus or species. Noteworthy is the large size of the Muhi gulars that corresponds to a body length of about 1.6 m the length of Latimeria today. The gulars are preserved in association with a basibranchial tooth plate and a few neural spines. This is the third actinistian record from the Cretaceous of Mexico.

1 Introduction

There are many Cretaceous marine localities in Mexico with fossil shes (Gonzlez-Rodrguez et al., 2013a). Different chondrichthyans and a rich actinopterygian fauna are known, but only two actinistian are recorded: one from Tlaya (Espinosa-Arrubarrena et al., 1996 [specimen lost]) and another from Vallecillo (Schultze et al., 2010). The Muhi quarry of Hidalgo state in central Mexico is AlbianCenomanian in age, more likely Albian based on the ammonite record (see Gonzlez-Rodrguez et al., 2013b, p. 459). Its rich teleostean fauna and few teleosteomorph aspidorhynchid and chondrichthyan remains are considered as unique (Gonzlez-Rodrguez et al., 2013a). Holosteans have not been discov-

Actinistian gular plates from the Cretaceous of Mexico and the problems assigning gular plates taxonomically

ered yet. The composition of the sh fauna clearly distinguishes the Muhi locality from other Mexican Cretaceous localities, specically from the slightly older Tlaya quarry in Puebla state with many holosteans (Amiiformes, Semionotiformes, and Macrosemiiformes) and Pycnodontiformes. Pycnodontiformes also occur in younger Upper Cretaceous localities of Mexico. The occurrence of specialized teleosts (two genera of armored acanthomorphs; Gonzlez-Rodrguez et al., 2013b) in Muhi quarry is interpreted as endemism (Gonzlez-Rodrguez et al., 2013a).

Actinistian remains are new at Muhi quarry. The actinistian gulars described here were discovered in December 2013 and May 2014, respectively. Actinistians possess a pair of gulars that are interpreted as homologous to lateral gulars (Jollie, 1962, g. 4-33; Forey, 1998, p. 270); a median gular is unknown in actinistians. Lateral gulars of actinistians are very characteristic (Hagdorn and Mutter, 2011; Hauser and Martill, 2013, g. 6: gular plates of different osteichthyans and distinct actinistian gular) and easily identied with a little experience; for example, a teuthoid gladius in Fuchs et al. (2008) was recently reinterpreted as a gular of an actinistian by Schultze et al. (2010).

2 Material and methods

Material: the actinistian record of Muhi quarry is based on one left gular plate (UAHMP 3966) and on a partial gular plate associated with a basibranchial tooth plate (UAHMP 3970). The left gular plate was deposited with the outer surface on the sediment so that the deepened inner surface of the gular was lled with additional layers of sediment, which pitch out laterally as seen on the lateral side of the

Published by Copernicus Publications on behalf of the Museum fr Naturkunde Berlin.

102 H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico

Figure 1. Limestone block UAHMP 3966 with a left lateral gular plate and ve neural spines. Scale bar 10 cm.

block. The partial gular plate is also preserved on the lower side of the block.

On both blocks, elongated elements with a broad base occur besides the gulars. They are interpreted here as neural spines. In addition, there is an isolated neural arch with a short neural spine on specimen UAHMP 4408.

Methods: measurements were taken with a caliper. Measurements of published gures were calculated from the given scale. In cases where this was not possible, authors were asked for help (see acknowledgements). Preparation of the specimens was not necessary; only the margins of the left gular plate were cleaned with a needle. Photographs were taken

Foss. Rec., 19, 101117, 2016 www.foss-rec.net/19/101/2016/

H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico 103

Figure 2. Left gular plate UAJMP 3966; (a) photo (scale in cm) and (b) drawing. Drawings of (c) left gular plate of Libys polypterus after Hauser and Martill (2013, g. 5B) and of (d) left gular plate of Triassic actinistian indet. after Hauser and Martill (2013, g. 3b). Arrows point anteriad. Scale bars 1 cm.

with a Nikon Coolpix P4 digital camera, and drawings were made using a Wild M5A stereomicroscope with a camera lucida attachment.

Institutional abbreviations: AMNH, American Museum of Natural History, Vertebrate Collections, New York, New York, USA; KUI, University of Kansas, Natural History Museum and Biodiversity Institute, Ichthyology collection, Lawrence, Kansas, USA; KUVP, University of Kansas, Nat-

ural History Museum and Biodiversity Institute, Vertebrate

Paleontology collection, Lawrence, Kansas, USA; MHNM, Muse dHistoire naturelle de Miguasha, Parc de Miguasha, Quebec, Canada; PU, former Princeton University Geological Museum, now at Peabody Museum, Yale University, New Haven, Connecticut, USA; UAHMP, Museo de Pale-ontologa, Universidad Autnoma del Estado de Hidalgo,

www.foss-rec.net/19/101/2016/ Foss. Rec., 19, 101117, 2016

it attens posteriad. Striae run on the middle ridge and parallel to the ridge, and a few small and short ridges are close to the posterior lateral margin of the gular plate.

3.2 Basibranchial tooth plate

A smaller bone lies below the gular (Fig. 3); its shape is more or less triangular. Small plates with small teeth lie on the surface of the bone; we interpret this bone as a basibranchial tooth plate, by comparison with similar elements in other actinistians (e.g., Latimeria: copula of Smith, 1940, g. 8;Diplurus: Schaeffer, 1952, g. 8 and pl. 12, g. 2; Latimeria: Nelson, 1969, g. 14C: posterior part of the paired tooth plate series of [branchial] arch 2, pl. 81, g. 1; Megalocoelacanthus: posterior tooth plate of basibranchial in Dutel et al., 2012, g. 16A, of which the posterior end of the posterior basibranchial tooth plate is visible; Smith, 1940, pl. 23;Dutel et al., 2012, g. 16A).

3.3 Neural spines and arches

Four elongated elements lie dispersed around and one on top of gular UAHMP 3966 (Fig. 1). The elements (Fig. 4af) have long narrow spines up to 63 mm long. The spines are round in diameter above the arch but show a median furrow in more distal parts; this condition indicates that only the outside of the spine was ossied, and the center was hollow (see reconstructed cross section of neural spines of Laugia groenlandica in Stensi, 1932, g. 20 showing a similar pattern), so that it collapsed during compaction. A small canal appears in the lower round part of the neural spine above the joint of the two parts of the neural arch; it is the canal for the dorsal ligament (Andrews, 1977, gs. 13). The neural arches dorsally surround an ossied rounded sheet of about 14 to 18 mm in depth. The notochordal sheet is either smooth or divided into small pieces. In one spine (Fig. 4ab), a hemal process (13 mm long) is attached to the lower side of the rounded sheet. This neural spine is interpreted

Foss. Rec., 19, 101117, 2016 www.foss-rec.net/19/101/2016/

104 H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico

Table 1. Measurements of neural spines of the indet. actinistians from Muhi quarry.

Spine Arch Center Position length length diameter

Spine A 63 mm 11 mm 14 mm on UAHMP 3966 below gular

Spine B 55 mm 10 mm 12 mm on UAHMP 3966 above and posterior to gular

Spine C 60 mm 10 mm on UAHMP 3966 above middle gular

Spine D 50 mm 812 mm 18 mm on UAHMP 3966 above anterior tip of gular

Spine E (44 mm) 9 mm on UAHMP 3970

Spine F 12 mm 6 mm 16 mm on UAHMP 4408

Pachuca, Hidalgo, Mexico; USNM, United States National Museum, Smithsonian Institution, Washington, D.C., USA.

3 Morphological description

3.1 Gular plates

On block UAHMP 3966 (Fig. 1), the left gular plate is preserved together with ve elongated elements (largest 63 mm long). The preserved part of the gular plate (Fig. 2ab) is 253 mm long; the gular plate with a reconstructed posterior end may have reached a length of 280 mm. It is narrow, 40 or 50 mm wide in the anterior part (1417 % of total length) and 62 mm at its greatest width (22 % of total length). The anterior half of the gular is preserved in bone; the lateral margin continues up to three-quarters of the total length of the gular.The medial margin cannot be followed so far back because of incomplete preservation. The posterior half is eroded so that only the outline of the gular is visible.

The left gular plate (Fig. 2ab) is seen from its ventral (outer) side. It is narrow compared to gular plates of other actinistians, pointed at its anterior end. It widens somewhat in its posterior part on the lateral side. The medial border is straight. The anterior part is at with a strong medial ridge, which rises in height from the tip of the gular plate posteriad and continues to the wide elevation at the middle of the plate.There are two short low ridges lateral to the anterior end of the medial ridge. The at area lateral to the medial ridge is bordered laterally by another ridge, which starts 90 mm posterior to the anterior tip (width of the gular plate at this point is 49 mm). The lateral ridge and the at area extend to the elevated area of the middle region. The elevated area attens out laterad, where the gular plate is widest (62 mm). The gular lacks ornamentation and any trace of a pit line.

A smaller gular plate on limestone block UAHMP 3970 (Fig. 3) is only partly preserved. A section (75 mm) of the anterior portion is preserved. The middle ridge is prominent;

H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico 105

Figure 3. Specimen UAHMP 3970: partly preserved gular at the top, branchial plate with teeth below the gular, and one neural spine at the bottom. Scale bar 1 cm.

here as belonging to the posterior abdominal region because of the short hemal process (compare with Andrews, 1977, g. 3A). The other spines (Fig. 4ce) cannot be placed in any specic body region. They could be spines of the abdominal or caudal region, where the notochord is narrow and the space for the neural cord minimal (Millot and Anthony, 1958, pl. 75; Andrews, 1977, g. 4; Arratia et al., 2001, g. 29C).There is one isolated rounded structure with a short neural spine (UAHMP 4408, Fig. 4g). By comparison with Latimeria (Millot and Anthony, 1958, pl. 50), this neural arch is interpreted as belonging to the most anterior part of the axial skeleton, close to the head. A mineralized, rounded sheet appears in place of the notochord; it is missing in the neural

spine (Fig. 4c), lying above the posterior part of gular plate UAHMP 3966, preserved laterally and showing only the neural arch of both sides superimposed on each other next to the spine.

The spine (Fig. 4d) above the middle part of gular UAHMP 3966 shows the notochordal sheet divided into two half-moons. The size of these elongated elements (Table 1), interpreted as neural spines, corresponds to the size of the neural spine of Megalocoelacanthus (Dutel et al., 2012, g. 19A), an actinistian even larger than the one of Muhi quarry.

www.foss-rec.net/19/101/2016/ Foss. Rec., 19, 101117, 2016

106 H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico

Figure 4. (ae) Specimen UAHMP 3966: (a) neural spine with hemal process below gular plate, (b) drawing of (a, c), neural spine above posterior part of gular, (d) neural spine above middle part of gular, (e) neural spine above anterior part of gular, (f) neural spine on specimen UAHMP 3970, and (g) neural spine from the region behind the skull, UAHMP 4408. Scale bars 1 cm.

4 Comparison

Gular plates have been recorded and described in many actinistians (Table 2), but they have never received special attention. They are paired and easily recognizable in fossil and living actinistians (Schultze et al., 2010; Hauser and Mar-till, 2013). Actinistians possess only lateral gulars; a median is missing. Thus the anterior tips of the lateral gular plates lie close together or touch each other in contrast to other sarcopterygians (except onychodonts: Jessen, 1966, g. 6C, and Andrews et al., 2006, gs. 13, 46a, c) and primitive actinopterygians where the anterior tips of the lateral gu-lars form a triangular space to accept the median gular (e.g., Schultze and Campbell, 1986, g. 5). Lateral gular plates of actinistians and onychodonts meet in a straight median line, the actinistian gulars nearly along the whole midline, whereas the onychodont gular plates have a large postero-laterally extending part. The lateral margin of the actinistian gular plates is continuously convex, often symmetrically (see Figs. 5 and 6). The lateral part overlaps the lower jaw, whereas it borders the submandibulars in other sarcopterygians. The combination of straight median margin with a

continuous convex lateral margin is the tool to recognize isolated gular plates as those of actinistians.

Schaeffer (1941, 1952) compared different skeletal elements of many actinistian taxa, and he demonstrated differences useful for characterization of taxa. However, he did not use gulars, supposedly because they show few distinctions among taxa. Cloutier (1996, g. 9) illustrated gulars of three Devonian actinistian genera. Schultze et al. (2010) cited records for ve species and genera including the extant actinistian Latimeria chalumnae. Hauser and Martill (2013, g. 4) gured eight gulars of seven fossil genera and one indet. Searching the literature, we found gulars of 61 species gured in external or internal view (see Table 2). In addition, 13 are illustrated in lateral view so that only the length could be measured or estimated.

Identication of left and right gulars: it is not easy to distinguish between right and left gulars if they are not found in contact. Hauser and Martill (2013, p. 983, g. 3) described a Triassic gular as a right gular. However, they gured it as a left gular in a comparative gure (Hauser and Martill, 2013, g. 4h). In Latimeria, the anterior pointed ends of the gulars are close to each other in the midline, whereas the poste-

Foss. Rec., 19, 101117, 2016 www.foss-rec.net/19/101/2016/

H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico 107

Table 2. Measurements of gular plate length and total body length of different coelacanth species. Explanations: (number) measurement of gular length in lateral view; g gular; l length; le left; ri right; Sp total length of specimen; w width; 80 (bold) measurement by the author; [number] measurements taken from Hauser and Martill (2013, table 2). Remarks: Forey (1998): all gures are drawings (reconstructions) except Sassenia; Lund and Lund (1985): all gures are drawings.

Species Fig. (in this paper) g length g width Sp length gl/gw gl/Spl original reference in mm in mm in mm

Alcoveria brevis Fig. 6Y

Beltan (1972), pl. 1, gs. A, B 20.3 4.93 9.7 4.12 0.255

Allenypterus montanus Fig. 6b

Lund and Lund (1985), gs. 60, 57 16.5 3.68 63.5 4.48 0.26 Forey (1998), g. 4.6 12.25 2.94 4.17

Axelrodichthys araripensis Fig. 5M

Hauser and Martill (2013), tbl. 2 [50] no scale [405] [0.124]

Maisey (1991), g. on p. 308 54.37

Forey (1998), g. 4.17 (54.9)

Forey (1998), g. 11.3 (150)

Maisey 3.6.15 94 21 710 4.48 0.324

Caridosuctor populosum Fig. 6B

Lund and Lund (1985), g. 21 65.4 19.2 3.4Lund and Lund (1985), g. 22 28.8 (same specimen) 8.65 3.3Lund and Lund (1985), g. 19 (19.5) 113.8 0.171

Chagrinia enodis Fig. 6T

Cloutier (1996), g. 9D 24 7.2 3.3

Chinlea sorenseni Fig. 5J

Elliott (1987), g. 2BElliott 27.1.15 101.8 27.9 3.67

Coccod. nudum = suevicum

Reis (1888), pl. 3, g. 1 31 9 3.44

Coccoderma substriolatum

Huxley (1866), pl. 10, g. 4 > 86 29 > 3.1

Coccodermasuevicum Fig. 6DForey (1998), g. 4.11, 31.2 7.5 4.16 Forey (1998), g. 5.7 39.8 10.3 3.86 Lambers (1992), p. 11 305Vetter (1881), pl. 2, g. 4 50 12 4.2

Coelacanthidae gen. sp. indet. Fig. 6L 22115

Hagdorn and Mutter (2011), p. 233, 22115g. 7j 39 13 3.0

Coelacanthus granulatus Fig. 6F

Schaumberg (1978), g. 4 48.55/38.7 11.14/9.12 4.36/4.24Forey (1998), g. 11.4 (50.6) 404.6 0.125

Diplocercides heiligenstockensis Fig. 6d

Cloutier (1996), g. 9C 13.6 4.1 3.3

Diplocercides jaekeli Fig. 6S

Stensi (1937), pl. 10, g. 3 24.8 ?7.2 3.45 Stensi (1937), pl. 8, g. 1 24.9 6.5 3.83

Diplocercides kayseri Fig. 6O

Cloutier (1996), g. 9B 29.7 6.8 4.37 Stensi (1937), g. 18 (26)

Diplocercides sp. Fig. 6I

Szrek (2007), g. 4 le 44/ri 40.2 le 10.74/ri 9.22 4.1/4.36

www.foss-rec.net/19/101/2016/ Foss. Rec., 19, 101117, 2016

108 H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico

Table 2. Continued.

Species Fig. (in this paper) g length g width Sp length gl/gw gl/Spl original reference in mm in mm in mm

Diplurus gwyneddensis

Bock (1959), tbl. p. 43 38 10 3.8

Diplurus longicaudatus Fig. 5G

Bock (1959), tbl. p. 43 140 40 3.5Schaeffer (1952), tbl. 1 (140) 640 0.219 USNM18476 pl. 16, g. 2 le 143/ri 140 le 42/ri 38 3.4/3.68

Diplurus newarki Fig. 6Z

Schaeffer (1952), g. 8 12.9 2.9 4.45 reconstruction g. 9 16 140 0.114 PU14945, tbl. 1 61.5AMNH15222, tbl. 1 [13] 86.2[159] 0.083

PU14918, tbl. 1 [15] 110[80] 0.082

PU14943, pl. 8 17.5 3.2 80 5.47 0.219 PU14944, pl. 5, g. 3, (12) 115 0.104 pl. 9, g. 1 12 2.6 4.62PU14959, tbl. 1 131Schaeffer (1941), g. 2C, 10.4 2.57 4.05p. 2 11 2.7 110 4.07 0.100 Bock (1959), tbl. p. 43 16.5 3 140 5.5 0.118 Forey (1998), g. 11.6 (10.8) 98.4 0.110

Dobrogeria aegyssensis Fig. 5N

Cavin and Gradinaru (2014), g. 12 88.6 29.9 2.96

Garnbergia ommata

Martin and Wenz (1984), g. 1 (65)

Graphiurichthys callopterus

Kner (1866), pl. 1, g. 1 21.45 4.45 82 4.82 0.262

Guizhoucoelacanthus guanlingensis Fig. 5Q

Geng et al. (2009), g. 1 (76.2) 354.8 0.215 Geng et al. (2009), g. 2 73.7 ?15.2 ?4.85

Hadronector donbairdi Fig. 6a

Lund and Lund (1985), gs. 35/36 16.75 3.25 69.5 5.15 0.241

Holophagus gulo Fig. 6N

Forey (1998), g. 11.8 Holophagus sp. (100) 589.2 0.170 Gardiner (1960), pl. 43, g. 2 30.5 9 3.4

Indocoelacanthus robustus Fig. 5H

Jain (1974), g. 2 120.3/126.9 31.7/34.6 3.79/3.67 pl. 1, g. 1 131 37 3.54

Latimeria chalumnae KUI 22082 male 148 48 972 3.08 0.152

Latimeria chalumnae female Fig. 5D

Smith (1940), p. 9, pl. 9 (?female, estimated from size) 225 66 1434.8 3.4 0.195 Millot and Anthony (1958), g. 6 177 58 3.05Forey (1998), g. 8.1 (281.4) 1434.8 0.195

Latimeria chalumnae embryo

Forey (1998), g. 2.3 86.6 ri 25.6/le 26.8 3.38/3.23

Laugia groenlandica Fig. 6V

Stensi (1932), pl. 1, g. 2 21.2 6 131.3 3.53 0161 Forey (1998), g. 4.10 (21.8)

Forey (1998), g. 11.10 (25.6) 139.02 0.184

Libys polypterus Figs. 2C. 5R

Reis (1888), pl. 2, g. 2 71.5 22 3.25 Hauser and Martill (2013), g. 5B LipHM 56.9 11.25 5.05

Foss. Rec., 19, 101117, 2016 www.foss-rec.net/19/101/2016/

H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico 109

Table 2. Continued.

Species Fig. (in this paper) g length g width Sp length gl/gw gl/Spl original reference in mm in mm in mm

Lochmocercus aciculodontus Fig. 6e

Lund and Lund (1985), g. 68 12.6 (2.4) 73.4 (5.3) 0.172

Luopingcoelacanthus eurylacrimalis Fig. 6K

Wen et al. (2013) g. 1A/5A 53.4/38.3 14.7/10.4 /150.4 3.63/3.68 /0.255 Wen 2.2.14 40 10 4

Lualabaea lericheide Saint-Seine (1955), pl. 2 17 4.5 3.78

Macropoma lewesiensis

Forey (1998), g. 4.19 (86.96)

Forey (1998), g. 11.11 (112.1) 457.7 0.245

Macropoma mantelli Fig. 5O

Woodward (1909), pl. 37, g. 9 68 21 3.24Woodward (1909), pl. 37, g. 10 77 19 4.05Woodward (1909), g. 49 (81) 429 0.189

Macropoma precursor

Woodward (1909), pl. 38, g. 8 (39)

Macropoma speciosum

Tima (1986), pl. IV (67.3/77.3) 375/431.3 0.179

Macropoma willemoesii

Vetter (1881), pl. 1, g. 1 (41) 245 0.167

Macropomoides orientalis

Forey (1998), g. 11.21 (13) 63.6 0.204

Mawsonia brasiliensis Fig. 5F

Hauser and Martin (2013), tbl. 2 [189] [929] [0.204]

Yabumoto (2002), g. 4 176.9 50.7 1006.7 3.49 0.176

Mawsonia gigas Fig. 5B

Woodward (1907) pl. 8, g. 5 337.5 91.2 3.7

Mawsonia sp. Fig. 6E

Gallo et al. (2010), g. 5 49.5 18.4 2.69

Megalocoelacanthus dobiei Fig. 5A

Dutel et al. (2012), g. 14C 400 125.3/128.9 3.19/3.1 Cast 404/403 130/129.9 3.1/3.11 Maisey 3.6.15 475 150 3.17

Miguashaia bureaui Fig. 6G

Cloutier (1996), MHNM 06-41, g. 9A 48.2 13.8 195 3.49 0.247

Mylacanthus lobatus

Stensi (1921), pl. 18, g. 4 ?45 19 ?2.37

Mylacanthus spinosus

Stensi (1921), pl. 19, g. 3 > 62 31 > 2

Palaeoctopus pelagicus Fig. 6A

Fuchs et al. (2008), p. 1133, g. 6 70 20 3.5Schultze et al. (2010), p. 690 66 about 600 0.110

Parnaibaia maranhaoensis Fig. 6H

Yabumoto (2008), g. 2 47.8 [56] 11.9 363.4 4.0 [4.7] 0.132

Yabumoto (2008), g. 3 41.4 [50] 10.3 [11.3] 4.0 [4.4]

Yabumoto (Feb. 2015) 45.0[52.7] 10.8 4.17 [4.88]

Piveteauia madagascariensis Fig. 6WHauser and Martin (2013), tbl. 2 [23] [87] [0.269]

Clment (1999), gs. 1, 2 20.4 5.9 130140 3.46 0.151

www.foss-rec.net/19/101/2016/ Foss. Rec., 19, 101117, 2016

110 H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico

Table 2. Continued.

Species Fig. (in this paper) g length g width Sp length gl/gw gl/Spl original reference in mm in mm in mm

Polyostorhynchus simplex

Lund and Lund (1985), g. 46 (24.9) 127.8 0.160

Reidus hilli Fig. 6M

Graf (2012), g. 2A, D le 36.6/ri 36.1 le 9.9/ri 9.2 3.7/3.92

Rhabdoderma ? abdenense Fig. 6C

Moy-Thomas (1937), pl. 4, g. E 50.7 13.3 3.81

Rhabdoderma (?) aldingeri Fig. 6U

Moy-Thomas (1937), p. 409, g. 15 23 4.5 5.1

Rhabdoderma ardrossense

Moy-Thomas (1937), pl. 2 11.56 ? 85 0.136

Rhabdoderma elegans Fig. 6P

Moy-Thomas (1935), g. 10 (23.2) 6.4 3.64Forey (1981), g. 6/9 (27.4)/(23.2) 124 0.187 Forey (1998), g. 11.14 (23.2) 123.2 0.188

Rhabdoderma huxleyi

Traquair (1881), p. 21 10.75 1.8 64.5 6 0.167

Rhabdoderma lepturus

Huxley (1866), pl. 2, g. 1 26 7 107 3.71 0.243 Huxley (1866), pl. 4, g. 1 27 7.2 3.75

Rhabdoderma madagascariensis

Woodward (1910), pl. 1, g. 5 (25)

Moy-Thomas (1935), g. 9 (22.6) (6) 150 (3.77)

Rhabdoderma tingleyense Fig. 5P

Davis (1884), pl. 47, g. 1 76.6 23.6 3.24 Davis, (1884), pl. 47, g. 6 67.6 22.4 3.02

Sassenia groenlandica

Forey (1998), g. 11.16 (46.7)

Forey (1998), g. 4.13 (47.5)

Scleracanthus asper Fig. 5L

Stensi (1921), pl. 19, g. 1 95 34 2.79

Serenichthys kowiensis juvenile

Gess and Coates (2015), g. 2A, C 8.9 1.8 3060 4.9R. Gess 23.11.15 8.85 1.7 5.2

Spermatodus pustulosus

Westoll (1939), g. 2a (87.4)

Swenzia latimerae

Hauser and Martill (2013), tbl. 2 [29] [158] [0.181]

Clment (2005), g. 3 (42.5) 204 0.208

Synaptotylus newelli

Echols (1963)

KUVP 11457 17.5 5.36 3.26 KUVP 11429 18.619.5 5.86.5 33.29 KUVP 11431 20.7 5.6 3.7 KUVP 11432 ri 22.4 6.5 3.41 KUVP 11428 22/21.6 6.6/6.3 3.33/3.4 KUVP 11424 30.3 6.96 4.35 KUVP 156059a le Fig. 5K 96.6 27.5/30 3.51

Foss. Rec., 19, 101117, 2016 www.foss-rec.net/19/101/2016/

H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico 111

Table 2. Continued.

Species Fig. (in this paper) g length g width Sp length gl/gw gl/Spl original reference in mm in mm in mm

Ticinepomis peyeriHauser and Martill (2013), tbl. 2 [17] [125] [0.136]

Rieppel (1980), g. 6 (6.4) 44.6 0.143

Trachymetopon liassicum Fig. 5EHennig (1951), tbl. p.70 210 55 1640 3.82 0.128

(1750) (0.12)

Hennig (1951), pl. 8, g. 5 180 71 2.54Hauff and Hauff (1981), g. 70 170 66 1317.5 2.58 0.181 Dutel et al. (2015), p. 2 1600Dutel et al. (2015), g. 1A ?238 > 1700Dutel et al. (2015), g. 3B 168.5 69.7 2.42

Triassic coelacanth indet. Figs. 2D, 5IHauser and Martill (2013), gs. 3a, b, 4h 110.2 24.9 4.42

Undina acutidens Fig. 6JReis (1892), pl. 2, g. 10 43 10.8 255 3.98 0.169

Whiteia nielseni Fig. 6XForey (1998), g. 5.9D 20.4 5.5 3.71

Whiteia tuberculata Fig. 6CForey (1998), g. 5.9F 10.1 2.8 3.6 Lehman (1952), g. 14 (17)

Lehman (1952), pl. 4, g. C 14.5 4.4 3.3

Whiteia woodwardi Fig. 6RLehman (1952), g. 13 (24) 127 0.189 Lehman (1952), g. 9A 26.4 7.6 3.47Lehman (1952), pl. 1 25.6 7.3 3.5Lehman (1952), pl. 2, g. C 25 8.6 2.9Forey (1998), g. 4.15 (32.8)

Forey (1998), g. 11.18 (32.4) 146.7 0.221

Youngichthys xinghuainsisWang and Liu (1981), g. 3 (10) 132

Muhi quarry spec.

UAHMP 3966 Figs. 2A, B, 5C 253280 62 4.52

rior ends diverge from each other (Smith, 1940, pl. 9). By comparison with Latimeria, we prefer to orient the gulars of Megalocoelacanthus (Fig. 5) in the opposite way to Dutel et al. (2012, g. 14C), reecting the condition in Latimeria. The same morphology can be seen in Libys polypterus (Hauser and Martill, 2013, g. 5A, B), Macropoma mantelli (Woodward, 1909, pl. 37, g. 9), Undina acutidens (Reis, 1892, pl. 2, g. 10), and Whiteia woodwardi (Lehman, 1952, g. 9A), where both gulars are preserved in situ. In Reidus, both gulars are close to each other along the whole midline and separated a little only at their most posterior part (Graf, 2012, g. 2A, D).

Gular size: the length of the gulars is correlated with the body length (Fig. 7). Most fossil actinistians and their gu-lars are small (Figs. 5 and 6); only a few fossil actinistians and their gulars (Fig. 5ef) are comparable in size with La-

timeria chalumnae and its gulars (Fig. 5d). The gular from Muhi quarry (Fig. 5c) corresponds closely to the length of the gular of Latimeria chalumnae (Fig. 7), whereas the gulars of Mawsonia gigas and of Megalocoelacanthus dobiei (Fig. 5ab) are longer than the gular of Latimeria chalumnae. Naturally, size changes with growth (compare gular length given by Forey, 1998, for an embryo of Latimeria of 86.6 mm with that of 225 mm in adults; Table 2). The same can be seen in fossil actinistians (e.g., Synaptotylus from 17.5 to 96.6 mm in length; Table 2). Hagdorn and Mutter (2011) cited gulars of 22 to 115 mm length from one Triassic geological horizon and interpreted them as growth stages of one species. Figure 6 shows that most gulars are small, because most fossil actinistians are small. The gular of Serenichthys kowiensis (Gess and Coates, 2015) is the smallest gular of all gured gulars; the specimens are interpreted as juvenile by the au-

www.foss-rec.net/19/101/2016/ Foss. Rec., 19, 101117, 2016

112 H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico

Figure 5. Large left gular plates of actinistians in external view in descending size: (A) Megalocoelacanthus dobiei (Dutel et al. 2012, g. 14C; size after measurement of J. Maisey), (B) Mawsonia gigas (Woodward, 1907, pl. 8, g. 5), (C) Muhi gular UAHMP 3966, (D) Latimeria chalumnae (female, Smith, 1940, p. 9, pl. 9), (E) Trachymetopon liassicum (Hennig, 1951, pl. 8, g. 5), (F) Mawsonia brasiliensis (Yabumoto, 2002, g. 4). (G) Diplurus longicaudatus (Bock, 1959, g. 6B), (H) Indocoelacanthus robustus (Jain, 1974, g. 2), (I) Triassic coelacanth (Hauser and Martill, 2013, g. 3a, b), (J) Chinlea sorensensis (Elliott, 1987, g. 2B), (K) Synaptotylus newelli (large specimen KUVP 156059a), (L) Scleracanthus asper (Stensi, 1921, pl. 19, g. 1), (M) Axelrodichthys araripensis (Maisey, 1991, g. on p. 308),(N) Dobrogeria aegyssensis (Cavin and Gradinaru, 2014, g. 12), (O) Macropoma mantelli (Woodward, 1909, pl. 37, g. 10), (P) Rhabdoderma tingleyensis (Davis, 1884, pl. 47, g. 1), (Q) Guizhoucoelacanthus guanlingensis (Geng et al., 2009, g. 2), (R) Libys polypterus (Reis, 1888, pl. 2, g. 2). Scale bar 5 cm.

thors. In Table 2 and Fig. 7, the largest gular was used in each case to compare with or estimate the length of the sh.

In addition, sexual differences should be considered as shown by Latimeria chalumnae, since adult females (max: 2 m long) are larger than males (max: 1.68 m long) in the extant coelacanth Latimeria. This proportional length ratio between Latimeria female and male is also proportionally present in the length of their gular plates (Table 2: length of female Latimeria gular 225 mm versus length of male Latimeria gular 148 mm). Unfortunately, the distinction between sexes is not possible in most fossils, because there are no external features distinguishing the sexes. The gular of the Muhi actinistian belongs to the exceptionally long gu-lars. The left Muhi gular is longer than those of Latimeria

chalumnae listed in Table 2. Only the gulars of Mawsonia gigas and Megalocoelacanthus dobiei are longer than that of the Muhi actinistian. In the relationship of gular length to body length, the Muhi gular corresponds to a body length of about 1.621.64 m (Fig. 7). All large actinistians with a body length above 1 m are from the Cretaceous and Recent and one (Trachymetopon) from the Jurassic; they belong to either the Latimeriidae or Mawsoniidae. The Triassic Wimania (family Whiteiidae) may reach a size over 1 m also, but only the upper part of the head is known (Stensi, 1921), whereas gular and body are unknown.

The length / width ratio (g-l / g-w) of gulars varies from 2.5 (Trachymetopon liassicum) to 6 (Rhabdoderma huxleyi) in actinistians. Most g-l / g-w values lie between 3 and 4 (Ta-

Foss. Rec., 19, 101117, 2016 www.foss-rec.net/19/101/2016/

H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico 113

Figure 6. Small left gular plates in external view in descending size: (A) Palaeoctopus pelagicus (Fuchs et al., 2008, g. 6A), (B) Caridosuctor populosum (Lund and Lund, 1985, g. 21), (C) Rhabdoderma? abdenense (Moy-Thomas, 1937, pl. 4, g. E), (D) Coccoderma suevicum (Forey, 1998, g. 5.7, Vetter, 1881, pl. 2, g. 4), (E) Mawsonia sp. (Gallo et al., 2010, g. 5), (F) Coelacanthus granulatus (Schaumberg, 1978, g. 4), (G) Miguashaia bureaui (Cloutier, 1996, g. 9A), (H) Parnaibaia maranhaoensis (Yabumoto, 2008, g. 3), (I) Diplocercides sp. (Szrek, 2007, g. 4), (J) Undina acutidens (Reis, 1892, pl. 2, g. 10), (K) Luopingcoelacanthus eurylacrimalis (Wen et al., 2013, g. 1),(L) Coelacanthidae gen. indet. (Hagdorn and Mutter, 2011, g. 7j), (M) Reidus hilli (Graf, 2012, g. 2A), (N) Holophagus sp. (Gardiner, 1960, pl. 43, g. 2), (O) Diplocercides kayseri (Cloutier, 1996, g. 9B), (P) Rhabdoderma elegans (Moy-Thomas, 1935, g. 10), (Q) Rhabdoderma lepturus (Huxley, 1866, pl. 4, g. 2), (R) Whiteia woodwardi (Lehman, 1952, g. 9A), (S) Diplocercides jaekeli (Stensi, 1937, pl. 10, g. 3), (T) Chagrinia enodis (Cloutier, 1996, g. 9D), (U) Rhabdoderma? aldingeri (Moy-Thomas, 1937, g. 15), (V) Laugia groenlandica (Stensi, 1932, pl. 3, g. 2), (W) Piveteaui madagascariensis (Clment, 1999, g. 2), (X) Whiteia nielseni (Forey, 1998, g. 5.9D),(Y) Alcoveria brevis (Beltan, 1972, pl. 1, g. A), (Z) Diplurus newarki (Schaeffer, 1941, g. 2C), (a) Hadronector donbairdi (Lund and Lund, 1985, g. 35), (b) Allenypterus montanus (Lund and Lund, 1985, g. 60), (c) Whiteia tuberculata (Forey, 1998, g. 5.9F), (d) Diplocercides heiligenstockensis (Cloutier, 1996, g. 9C), (e) Lochmocercus aciculodontus (Lund and Lund, 1985, g. 68). Scale bar 1 cm.

ble 2; Fig. 8). Few gulars (12 species and 2 unnamed species) are narrow with g-l / g-w values between 4 and 5 as in the gular from Muhi quarry, and there are even fewer with g-l / g-w values over 5 (ve species including the Libys polypterus specimen of Hauser and Martill, 2013, g. 5B, which falls outside the normal size range of L. polypterus; Fig. 2C herein). The narrowness is not correlated with body length, nor with any systematic trait. All species with values over 5, except a Libys polypterus specimen gured by Hauser and Martill (2013, g. 5B), are Paleozoic forms. The Libys polypterus specimen of Hauser and Martill (2013, g. 5B) is different (g-l / g-w = 5.05) from specimens usu

ally identied as Libys polypterus with values of 3.25 (Table 2). The Triassic actinistian gular of Hauser and Mar-till (2013: g-l / g-w = 4.42; Fig. 2d), the Cretaceous Axel-

rodichthys araripensis (g-l / g-w = 4.48), the Carboniferous

Allenypterus montanus (g-l / g-w = 4.48), and the Triassic

Diplurus newarki (g-l / g-w = 4.45) show the closest values

to the gular of the Muhi actinistian (g-l / g-w = 4.52). Most

gulars with values between 4 and 5 belong to Paleozoic or

Triassic actinistians; only two are from the Cretaceous, Axelrodichthys and Parnaibaia, which are both members of

the family Mawsoniidae, to which also the Triassic Diplurus newarki belongs. The gular plates of the two Cretaceous species Axelrodichthys araripensis (Fig. 5m) and Parnaibaia maranhaoensis (Fig. 6h) present a shape different from that of the Muhi actinistian (Fig. 5c). There are Triassic gulars with comparable length / width values (the mawsoniid Diplurus newarki, Fig. 6z; the Triassic gular gured by Hauser and Martill, 2013, g. 3; Graphiurichthys callopterus, Kner, 1866, pl. 1, g. 1; and Guizhoucoelacanthus guanlingensis, Fig. 5R, with narrower gulars and higher values). The length / width ratio of the Muhi gular compares best with that of the Triassic actinistian gured by Hauser and Mar-till (2013; Fig. 2d herein).

Comparison with body length: the length of the Muhi gular lies between that of Mawsonia gigas and Latimeria chalumnae; it corresponds to a body length comparable to Latimeria chalumnae and Trachymetopon liassicum (Fig. 7). Nevertheless, Mawsonia gigas, Latimeria chalumnae, and Trachymetopon liassicum do not have long and narrow gulars (gl / gw values of 3.7, 3.13.4 and 2.53.8, respectively) similar to the Muhi actinistian. Gular shape does not correlate with body length. Greater body length is found in Mesozoic

www.foss-rec.net/19/101/2016/ Foss. Rec., 19, 101117, 2016

114 H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico

Figure 7. Correlation of gular length with body length: the length of the Muhi gular (253 to 280 mm) corresponds to a body length of 1620 to 1640 mm. Abbreviations: All Allenypterus montanus; Alv Alcoveria brevis; Ax Axelrodichthys araripensis; Coelg Coelacanthus granulatus; Dil Diplurus longicaudatus; Din Diplurus newarki; Gra Graphiurichthys callopterus; Gui Guizhoucoelacanthus guanlingensis; Ha Hadronector donbairdi; Hol Holophagus gulo; Laf Latimeria chalumnae female; Lau Laugia groenlandica; Loc Lochmocercus aciculodontus; Luo Luopingcoelacanthus eurylacrimalis; Mab Mawsonia brasiliensis; Mao Macropomoides orientalis; Mig Miguashaia bureaui; Mpl Macropoma lewesiensis; Mpm Macropoma mantelli; Msp Macropoma speciosum; Mw Macropoma willemoesii; Pap Palaeoctopus pelagicus; Par Parnaibaia maranhaoensis; Pi Piveteauia madagascariensis; Pol Polyosteorhynchus simplex; Rha Rhabdoderma ardrossense; Rhe Rhabdoderma elegans; Rhh Rhabdoderma huxleyi; Rhl Rhabdoderma lepturus; Sw Swenzia latimerae; Tic Ticinepomis peyeri; Tr Trachymetopon liassicum; Un Undina acutidens; Whw Whiteia wood-wardi; UAHMP 3966 Muhi gular.

and Recent actinistians, but it occurs in both families, Mawsoniiidae and Latimeriidae. The Muhi gular is narrow with a widening posterior portion (Fig. 2ab). A similar gular shape occurs in two Paleozoic forms, Rhabdoderma tingleyensis (Fig. 5p) and Caridosuctor populosum (Fig. 6b); the gulars of both Paleozoic species have a length / width ratio between 3 and 4 and cannot be considered narrow gulars.

Neural spines: the elongated elements around the gular are interpreted as neural arches even though they do not compare closely with the three-forked neural spines typical of fossil actinistians (Arratia et al., 2001, gs. 31, 32). In addition, unusual for actinistians, there appears to be a mineralized, rounded sheet in the place of the notochord. The size of these elongated elements (Table 1), interpreted as neural spines, corresponds to the size of the neural spine of Megalocoelacanthus (Dutel et al., 2012, g. 19A), an actinistian even larger than the one of Muhi quarry. The arch is bent and does not possess two straight halves as in most actinistians (e.g., Huxley, 1866, pl. 5, gs. 1, 2, 57; Stensi, 1932, g. 20C, E, pl. 2, g. 2, pl. 4, pl. 6, gs. 1, 2, pl. 7, g. 1, pl. 8; Schaeffer, 1952, pl. 5, gs. 13, pl. 6, g. 1, pl. 9, g. 1; Lund

and Lund, 1985, gs. 2, 3, 15, 19, 35, 46, 57; Yabumoto, 2008, g. 5, and many more). The features of the elongated elements compare with neural spines of large actinistians like Latimeria and Megalocoelacanthus.

5 Conclusions

The left gular plate found in the Muhi quarry belongs to a large actinistian of about 1.6 m. It is a supplementary taxon within the supposedly Albian sh fauna of the Muhi quarry in the Mexican state of Hidalgo. The shape of the gular, its length / width ratio, and the estimated body length are not diagnostic enough to refer these Muhi gular plates to any actinistian genus. Tentatively the new form is placed within the Mawsoniidae, because similar length / width ratios of the gular occur in three genera of Mawsoniidae: Axelrodichthys, Diplurus, and Parnaibaia. This is proposed with great caution, because shape and length / width ratio of gulars and body size are not correlated with a taxonomic unit within ac-

Foss. Rec., 19, 101117, 2016 www.foss-rec.net/19/101/2016/

H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico 115

Figure 8. Correlation of gular width with gular length: UAHMP 3966 below regression line indicates a narrow gular comparable to the gulars of the Triassic coelacanth gured by Hauser and Martill (2013), Diplurus newarki, Graphiurichthys and Guizhoucoelacanthus, the Jurassic Libys gured by Hauser and Martill (2013) and the Cretaceous Axelrodichthys. Abbreviations: All Allenypterus montanus; Alv Alcoveria brevis; Ax Axelrodichthys araripensis; Car Caridosuctor populosum; Cha Chagrinia enodis; Chi Chinlea sorenseni; Cns Coccoderma suevicum (two specimens); Coel ?Coelacanthidae gen. sp. indet. (Hagdorn and Mutter, 2011); Coelg Coelacanthus granulatus; Cos Coccoderma substriolatum; Dig Diplurus gwyneddensis; Dih Diplocercides heiligenstockensi; Dij Diplocercides jaekeli; Dil Diplurus longicaudatus; Din Diplurus newarki; Disp Diplocercides sp.; Dob Dobrogeria aegyssensis; Dyk Diplocercides kayseri; Gra Graphiurichthys callopterus; Gui Guizhoucoelacanthus guanlingensis; Ha Hadronector donbairdi; Hol Holophagus gulo; Ind Indocoelacanthus robustus; Lam Latimeria chalumnae male; Lae Latimeria chalumnae embryo; Laf Latimeria chalumnae female; Lau Laugia groenlandica; Lip Libys polypterus; LipHM Libys polypterus gured by Hauser and Martill (2013); Loc Lochmocercus aciculodontus; Lua Lualabaea lerichei; Luo Luopingcoelacanthus eurylacrimalis; Mab Mawsonia brasiliensis; Mag Mawsonia gigas; Masp Mawsonia sp.; Meg Megalocoelacanthus dobiei; Mig Miguashaia bureaui; Mpm Macropoma mantelli; Myl Mylacanthus lobatus; Pap Palaeoctopus pelagicus; Par Parnaibaia maranhaoensis; Pi Piveteauia madagascariensis; Rei Reidus hilli; Rha Rhabdoderma (?) aldingeri; Rhab Rhabdoderma ? abdenense; Rhe Rhabdoderma elegans; Rhh Rhabdoderma huxleyi; Rhl Rhabdoderma lepturus; Rhm Rhabdoderma madagascariensis; Rth Rhabdoderma tingleyense; Scl Scleracanthus asper; Sw Swenzia latimerae; Syn Synaptotylus newelli (different specimens); Tra Trachymetopon liassicum; Trco Triassic coelacanth indet. (Hauser and Martill, 2013); Un Undina acutidens; Whn Whiteia nielseni; Wht Whiteia tuberculata; Whw Whiteia woodwardi; UAHMP 3966 Muhi gular.

tinistians. Large size is until now only known from Triassic (Wimania) and younger actinistians.

The elongated elements associated with the gulars interpreted as neural spines are different from the three-forked neural spines typical of fossil actinistians. Their features compare with neural spines of large Cretaceous and Recent actinistians like Megalocoelacanthus and Latimeria.

Acknowledgements. We thank Sergio Yez and Victoria Labra (Zimapn, Hidalgo, Mexico) for the help in collecting the specimens. Measurements of published actinistians were taken from gured specimens. In some cases, when this was not possible or it was ambiguous, we asked colleagues for assistance. We thank especially R. Gess (Johannesburg, South Africa), D. Elliott (Flagstaff, Arizona, USA), J. Maisey (New York, USA), W. Wen (Chengdu, China), and Y. Yabumoto (Kitakyushu, Japan) for sending us mea-

surements of certain gular plates. We also contacted L. Hauser andD. Martill (both at Portsmouth, UK) concerning measurements of certain published specimens. U. Ghlich (Vienna, Austria) was so kind as to help us to get pictures of Macropoma speciosum (Reuss, 1857); the publication is available on the Internet, but the plates were photocopied folded. We thank A. Bentley (Lawrence, Kansas) for access to a male Latimeria specimen. J.-P. Mendau (Berlin, Germany) executed the nal line drawings based on the original illustrations done by the senior author. T. J. Meehan (Lawrence, Kansas) prepared the illustrations for electronic submission. We thank J. Priego (Pachuca) for helping with the statistical analysis.G. Arratia, T. J. Meehan, two anonymous reviewers, and G. Clment (Paris) read and corrected the manuscript.

Edited by: F. WitzmannReviewed by: G. Clment and two anonymous referees

www.foss-rec.net/19/101/2016/ Foss. Rec., 19, 101117, 2016

116 H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico

References

Andrews, S. M.: The axial skeleton of the coelacanth, Latimeria, in: Problems in Vertebrate Evolution, edited by: Andrews, S. M., Miles, R. S., and Walker, A. D., Linn. Soc. Symp. Ser. 4, Academic Press, London, 271288, 1977.

Andrews, S. M., Long, J., Ahlberg, P. E., Barwick, R., and Campbell, K. S. W.: The structure of the sarcopterygian Onychodus jandemarrai n. sp. from Gogo, Western Australia: with a functional interpretation of the skeleton, T. Roy. Soc. Edinb. Earth Sci., 96, 197307, 2006.

Arratia, G., Schultze, H.-P., and Casciotta, J.: Vertebral column and associated elements in dipnoans and comparison with other shes: Development and homology, J. Morphol., 250, 101172, 2001.

Beltan, L.: La faune ichthyologique du Muschelkalk de la Catalogne, Mem. Real Acad. Cienc. Art. Barcelona Terc Ep., 41, 281325, 1972.

Bock, W.: New eastern American Triassic shes and Triassic correlations, Natl. Acad. Sci. Geol. Center Res. Ser., Philadelphia, 1, 1184, 1959.

Cavin, L., and Gradinaru, E.: Dobrogeria aegyssensis, a new early Spathian (Early Triassic) coelacanth from North Dobrogea (Romania), Acta Geol. Polon., 64, 139145, 2014.

Clment, G.: The actinistian (Sarcopterygii) Piveteauia madagascariensis Lehman from the Lower Triassic of northwestern Madagascar: a redescription on the basis of new material, J. Vert.Paleontol., 19, 234242, 1999.

Clment, G.: A new coelacanth (Actinistia, Sarcopterygii) from the Jurassic of France, and the question of the closest relative fossil to Latimeria, J. Vert. Paleontol., 25, 481491, 2005.

Cloutier, R.: The primitive actinistian Miguashaia bureaui Schultze (Sarcopterygii), in: Devonian Fishes and Plants of Miguasha, Quebec, Canada, edited by: Schultze, H.-P. and Cloutier, R., Verlag Dr. Friedrich Pfeil, Mnchen, 227247, 1996.

Davis, J. W.: On a new species of Coelacanthus (C. tingleyensis) from the Yorkshire Cannel Coal, Trans. Linn. Soc. Lond. Ser.Zool., 2, 427433, 1884.de Saint-Seine, P.: Poissons fossiles de ltage de Stanleyville

(Congo belge). I. La faune des argilites et schistes bitumineux, Ann. Mus. Roy. Congo Belge Tervuren, Sr. in 8 , Sci. Gol., 14, 1126, 1955.

Dutel, H., Maisey, J. G., Schwimmer, D. R., Janvier, P., Herbin, M., and Clment, G.: The giant Cretaceous coelacanth (Actinistia, Sarcopterygii) Megalocoelacanthus dobiei Schwimmer, Stewart & Williams, 1994, and its bearing on Latimerioidei interrelationships, PLOS ONE, 7, e49911, doi:http://dx.doi.org/10.1371/journal.pone.0049911

Web End =10.1371/journal.pone.0049911 http://dx.doi.org/10.1371/journal.pone.0049911

Web End = , 2012.

Dutel, H., Herbin, M., and Clment, G.: First occurrence of a mawsoniid coelacanth in the Early Jurassic of Europe, J. Vert. Pale-ontol., 35, e929581, doi:http://dx.doi.org/10.1080/02724634.2014.929581

Web End =10.1080/02724634.2014.929581 http://dx.doi.org/10.1080/02724634.2014.929581

Web End = , 2015.Echols, J.: A New Genus of Pennsylvanian Fish (Crossopterygii, Coelacanthiformes) from Kansas, Univ. Kansas Publ. Mus.Natur. Hist., 12, 475501, 1963.

Elliott, D. K.: A new specimen of Chinlea sorensensi from the Chinle Formation, Dolores River, Colorado, J. Arizona-Nevada Acad. Sci., 22, 4752, 1987.

Espinosa-Arrubarrena, L., Applegate, S. P., and Gonzlez-Rodrguez, K. A.: The rst Mexican record of a coelacanth (Osteichthyes: Sarcopterygii) from the Tlayua quarries near Tepexi

de Rodrguez, Puebla, with a discussion on the importance of this fossil, in: Sixth North Amer. Paleontol. Convention, Abstr. Pap., edited by: Repetski, J. E., Paleontol. Soc. Spec. Publ., 8, 116, 1996.

Forey, P. L.: The coelacanth Rhabdoderma in the Carboniferous of the British Isles, Palaeontology, 24, 203229, 1981.

Forey, P. L.: History of the coelacanth shes, Chapman & Hall, London, 419 pp., 1998.

Fuchs, D., Ifrim, C., and Stinnesbeck, W.: A new Palaeoctopus (Cephalopoda: Coleoidea) from the Late Cretaceous of Vallecillo, North-eastern Mexico, and its implications on the evolution of Octopoda, Palaeontology, 51, 11291139, 2008.

Gallo, V., de Cavalho, M. M. S., and Santos, R. S. S.: New occurrence of Mawsoniidae (Sarcopterygii, Actinistia) in the Morro do Chaves Formation, Lower Cretaceous of the Sergipe-Alagoas Basin, Northeastern Brazil, Bol. Mus. Paraense Emilio Goeldi Cinc. Natur. Belm, 5, 195205, 2010.

Gardiner, B. G.: A revision of certain actinopterygian and coelacanth shes, chiey from the Lower Lias, Bull. Brit. Mus. (Natur. Hist.) Geol., 4, 239384, 1960.

Geng, B.-H., Zhu, M., and Jin, F.: A revision and phylogenetic analysis of Guizhoucoelacanthus (Sarcopterygii, Actinistia) from the Triassic of China, Vertebrate PalAsiatica, 47, 165177, 2009. Gess, R. W. and Coates, M. I.: Fossil juvenile coelacanths from the

Devonian of South Africa shed light on the order of character acquisition in actinistians, Zool. J. Linnean. Soc., 175, 360383, doi:http://dx.doi.org/10.1111/zoj.12276

Web End =10.1111/zoj.12276 http://dx.doi.org/10.1111/zoj.12276

Web End = , 2015.

Gonzlez-Rodrguez, K. A., Espinosa-Arrubarrena, L., and

Gonzlez-Barba, G.: An overview of the Mexican fossil sh record, in: Mesozoic Fishes 5 Global Diversity and Evolution, edited by: Arratia, G., Schultze, H.-P., and Wilson, M. V. H., Verlag Dr. F. Pfeil, Mnchen, 934, 2013a. Gonzlez-Rodrguez, K. A., Schultze, H.-P., and Arratia, G.:

Miniature armored acanthomorph teleosts from the Albian/Cenomanian (Cretaceous) of Mexico, in: Mesozoic Fishes 5 Global Diversity and Evolution, edited by: Arratia, G., Schultze, H.-P., and Wilson, M. V. H., Verlag Dr. F. Pfeil, Mnchen, 457487, 2013b.

Graf, J., A new Early Cretaceous coelacanth from Texas, Histor.Biol., 24, 441452, 2012.

Hagdorn, H. and Mutter, R. J.: The vertebrate fauna of the Lower Keuper Albertibank (Erfurt Formation, Middle Triassic) in the vicinity of Schwbisch Hall (Baden-Wrttemberg, Germany), Palaeodiversity, 4, 223243, 2011.

Hauff, B. and Hauff, R. B.: Das Holzmaden-buch, Selbstverlag,Holzmaden/Teck, 136 pp., 1981.

Hauser, L. M. and Martill, D. M.: Evidence for coelacanths in the Late Triassic (Rhaetian) of England, Proc. Geols. Assoc., 124, 982987, 2013.

Hennig, E.: Trachymetopon liassicum Ald., ein Riesen-Crossopterygier aus Schwbischem Ober-Lias, N. Jb. Geol. Palontol. Abh., 94, 6779, 1951.

Huxley, T. H.: Figures and descriptions illustrative of British organic remains. Dec. 12: Illustrations on the structures of the crossopterygian ganoids, Mem. Geol. Surv. UK, London, UK, 144, 1866.

Jain, S. L.: Indocoelacanthus robustus n. gen., n. sp. (Coelacanthidae, Lower Jurassic), the rst fossil coelacanth from India, J. Paleontol., 48, 4962, 1974.

Foss. Rec., 19, 101117, 2016 www.foss-rec.net/19/101/2016/

H.-P. Schultze and K. A. Gonzlez-Rodrguez: Actinistian gular plates from the Cretaceous of Mexico 117

Jessen, H. L.: Die Crossopterygier des Oberen Plattenkalkes (Devon) der Bergisch-Gladbach-Paffrather Mulde (Rheinisches Schiefergebirge) unter Bercksichtigung von amerikanischem und europischem Onychodus-Material, 1966, Ark. Zool., 18, 305391, 1966.

Jollie, M.: Chordate Morphology, Reinhold Publishing Corporation,New York, xiv, 478 pp., 1962.

Kner, R.: Die Fische der bituminsen Schiefer von Raibl in Krn-then, Sitzber. Akad. Wiss. Math.-Naturwiss. Cl. Wien, 53, 152 197, 1866.

Lambers, P. H.: On the ichthyofauna of the Solnhofen Lithographic Limestone (Upper Jurassic, Germany), Doctoral thesis, University of Groningen, X, p. 336, 1992.

Lehman, J.-P.: tude complmentaire des poisons de lEotrias deMadagascar, Kgl. Sv. VetenskAkad. Handl., 2, 1201, 1952.

Lund, R. and Lund, W. L.: Coelacanths from the Bear Gulch Limestone (Namurian) of Montana and the evolution of the Coelacanthiformes, Bull. Carnegie Mus. Natur. Hist., 25, 174, 1985.Maisey, J. G.: Axelrodichthys Maisey, 1986, in: Santana Fossils; an illustrated atlas, edited by: Maisey, J. G., TFH Publications, Neptune, New Jersey, 303315, 1991.

Martin, M. and Wenz, S.: Dcouverte dun nouveau coelacanth, Garnbergia ommata n. g., n. sp., dans le Muschelkalk suprieur du Baden-Wrttemberg, Stuttgarter Beitr. Naturkde. B, 105, 1 177, 1984.

Millot, J. and Anthony, J.: Anatomie de Latimeria chalumnae. TomeI. Squelette, muscles et formations de soutien, Centre National de la Recherche Scientique, Paris, 122 pp., 1958.

Moy-Thomas, J. A.: The coelacanth shes from Madagascar, Geol.Mag., 72, 213227, 1935.

Moy-Thomas, J. A.: The Carboniferous coelacanth shes of Great Britain and Ireland, Proc. Zool. Soc. Lond. B, 107, 383415, 1937.

Nelson, G. J.: Gill arches and the phylogeny of shes, with notes on the classication of vertebrates, Bull. Amer. Mus. Natur. Hist., 141, 475552, 1969.

Reis, O. M.: Die Coelacanthinen, mit besonderer Bercksichtigung der im Weissen Jura Bayerns vorkommenden Gattungen, Palaeontographica, 35, 194, 1888.

Reis, O. M.: Zur Osteologie der Coelacanthinen. I. Theil (Rumpfskelett, Knochen des Schdels und der Wangen, Kiemenbogenskelet, Schultergrtel, Becken, Integument und innere Organe), Inaug. Diss., Philos. Fak. Kgl. Ludwigs-Maximilians-Univ. Mnchen, 1888, 139, 1892.

Reuss, A. E.: Neue Fischreste aus dem bhmischen Plner, Denkschr. Akad. Wiss. Wien, Math.-Naturwiss. Cl., 13, 3342, 1857.

Rieppel, O.: A coelacanth sh from the Middle Triassic of Monte San Giorgio, Switzerland, Eclogae Geologicae Helvetiae, 73, 921939, 1980.

Schaeffer, B.: A revision of Coelacanthus newarki and notes on the evolution of the girdles and basal plates of the median ns in the Coelacanthini, Amer. Mus. Novitates, 1110, 117, 1941.Schaeffer, B.: The Triassic coelacanth sh Diplurus, with observations on the evolution of the Coelacanthini, Bull. Amer. Mus.Natur. Hist., 99, 2978, 1952.

Schaumberg, G.: Neubeschreibung von Coelacanthus granulatus

Agassiz (Actinistia, Pisces) aus dem Kupferschiefer von Richelsdorf (Perm, W.-Deutschland), Palontol. Z., 52, 169197, 1978. Schultze, H.-P. and Campbell, K. S. W.: Characterization of the dipnoi, a monophyletic group, J. Morphol., 1, 2537, 1987. Schultze, H.-P., Fuchs, D., Giersch, S., Ifrim, C., and Stinnesbeck,W.: Paleoctopus pelagicus from the Turonian of Mexico reinterpreted as a coelacanth (Sarcopterygian) gular plate, Palaeontology, 53, 689694, 2010.

Smith, J. L. B.: A living coelacanthid sh from South Africa, Trans.Roy. Soc. S. Afr., 28, 1106, 1940.

Stensi, E. A.: son: Triassic Fishes from Spitzbergen. Part 1,Holzhausen, A., Vienna, xxvii, 307 pp., 1921.

Stensi, E. A:son: Triassic Fishes from East Greenland, Meddel.Grnland, 83, 305 pp., 1932.

Stensi, E. A.: son: On the Devonian coelacanthids of Germany with special reference to the dermal skeleton, Kgl. Sv. VetenskAkad. Handl., 16, 156, 1937.

Szerk, P.: Coelacanths (Actinistia, Sarcopterygii) from the Famennian (Upper Devonian) of the Holy Cross Mountains, Poland, Acta Geologica Polonica, 57, 403413, 2007.

Tima, V.: Revision of Macropoma speciosum Reuss, 1857 (Crossopterygii, Coelacanthiformes). Vestnik strdniho Ustavu Geol. Praha, 61, 209216, 1986.

Traquair, R. H.: Report on the fossil shes collected by the Geological Survey of Scotland in Eskdale and Liddesdale. Pt. 1 Ganoidei, Trans. Roy. Soc. Edinburgh, 30, 1571, 1881.

Vetter, B.: Die Fische aus dem lithographischen Schiefer im Dresdener Museum, Mitt. Kgl. Mineral.-Geol. Mus. Prhistor. Slg. Dresden, 4, 1118, 1881.

Wang, N., and Liu, H.: [Coelacanth shes from the marine Permian of Zhejiang, South China], Vertebrata Palasiatica, 19, 305312, 1981.

Wen, W., Zhang, Q.-Y., Hu, S.-X., Benton, M. J., Zhou, C.-Y., Tao,X., Huang, J.-Y., and Chen, Z.-Q.: Coelacanths from the Middle Triassic Luoping Biota, Yunnan, South China, with the earliest evidence of ovoviviparity, Acta Palaeontol. Polon., 58, 175193, 2013.

Westoll, T. S.: On Spermatodus pustulosus Cope, a coelacanth from the Permian of Texas, Amer. Mus. Novitates, 1017, 123, 1939.

Woodward, A. S.: On the Cretaceous formation of Bahia (Brazil), and on vertebrate fossils collected therein. II. The vertebrate fossils, Q. J. Geol. Soc. Lond., 63, 131139, 1907.

Woodward, A. S.: The Fossil Fishes of the English Chalk, Part 5,

Palaeontographical Society, London, 153184, 1909. Woodward, A. S.: On some Permo-Carboniferous shes from

Madagascar, Ann. Mag. Natur. Hist., 5, 16, 1910.

Yabumoto, Y.: A new coelacanth from the Lower Cretaceous of Brazil (Sarcopterygii, Actinistia), Paleontol. Res., 6, 343350, 2002.

Yabumoto, Y.: A new Mesozoic coelacanth from the Lower Cretaceous of Brazil (Sarcopterygii, Actinistia), Paleontol. Res., 12, 329343, 2008.

www.foss-rec.net/19/101/2016/ Foss. Rec., 19, 101117, 2016