Canadian Journal of Earth Sciences
NEW EMBOLOMEROUS TETRAPOD MATERIAL AND A FAUNAL OVERVIEW OF THE MISSISSIPPIAN-AGED POINT EDWARD LOCALITY, NOVA SCOTIA, CANADA.
Journal: Canadian Journal of Earth Sciences
Manuscript ID cjes-2018-0326.R2
Manuscript Type: Article
Date Submitted by the 07-Jun-2019 Author:
Complete List of Authors: Adams, Gabrielle; Carleton University, Mann, Arjan; Carleton University, Earth Sciences; University of Toronto Faculty of Arts and Science, Earth Sciences Maddin, HillaryDraft C.; Carleton University, Mississippian, Carboniferous, tetrapod, embolomere, Point Edward Keyword: Formation
Is the invited manuscript for consideration in a Special Not applicable (regular submission) Issue? :
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4 Formatted for Canadian Journal of Earth Sciences
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6 NEW EMBOLOMEROUS TETRAPOD MATERIAL AND A FAUNAL OVERVIEW OF THE
7 MISSISSIPPIAN-AGED POINT EDWARD LOCALITY, NOVA SCOTIA, CANADA.
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9
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11 Draft
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14 Gabrielle R. Adams, Arjan Mann1, Hillary C. Maddin2. Department of Earth Sciences,
15 Carleton University, 1125 Colonel By Drive, Ottawa, ON K1S 5B6
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17 Corresponding author: Gabrielle R. Adams ([email protected])
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19 Keywords: Mississippian, Carboniferous, tetrapod, embolomere, Nova Scotia, Point Edward
20 Formation
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1 [email protected] 2 [email protected]
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23 NEW EMBOLOMEROUS TETRAPOD MATERIAL AND A FAUNAL OVERVIEW OF THE
24 MISSISSIPPIAN-AGED POINT EDWARD LOCALITY, NOVA SCOTIA, CANADA.
25
26 Gabrielle R. Adams, Arjan Mann, Hillary C. Maddin.
27 Abstract: Embolomerous tetrapods, mid-to-large aquatic predators, form a major faunal
28 constituent of Permo-Carboniferous tetrapod communities. Embolomeres are recognized by their
29 distinct circular, bipartite vertebrae. Although traditionally classified as stem amniotes, the
30 inclusion of embolomeres within the tetrapod crown group has recently been challenged. Despite
31 the group’s phylogenetic uncertainty, embolomeres provide an important record of a long-lived
32 tetrapod lineage, spanning ‘Romer’s Gap’Draft through to the Early Permian. Here we describe
33 embolomerous tetrapod material that was collected in 1915 by W. A. Bell (CMN 10015, herein
34 divided into CMN 10015A, B and C). The material, composed of numerous disarticulated cranial
35 and postcranial elements, was discovered near Sydney, Nova Scotia, as ex situ beach-float
36 pertaining to a horizon within the Mississippian-aged Point Edward Formation. Of this material,
37 a single left lower jaw of a proterogyrinid is identified, differing from previous embolomere
38 remains from this site identified as Pholiderpeton (?) bretonensis Romer, 1958. We also identify
39 an anterior jaw fragment as a separate taxon from the proterogyrinid, indicating the presence of
40 at least two embolomerous tetrapods in Bell’s collection. Other cranial and postcranial material
41 cannot be directly associated with either jaw and are not diagnostic enough to assign to a specific
42 taxon. Thus, the remaining material is referred to ‘Embolomeri indet.’ until more information is
43 available. Additionally, we summarize the fauna of the Point Edward locality revealing a diverse
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44 aquatic Late Mississippian ecosystem. Finally, the extensive embolomere material described here
45 presents new data that can broadly address embolomere diversity throughout the Carboniferous.
46 INTRODUCTION 47
48 Embolomeres are large aquatic tetrapods that occur in the fossil record from the
49 Early Carboniferous through to the Early Permian (Holmes 1989; Anderson et al. 2015). These
50 animals superficially resemble modern-day crocodilians and were among the largest predators of
51 their time. They are recognized in the fossil record by their bipartite vertebral centra, each
52 consisting of discrete, disc-shaped intercentrum and pleurocentrum (Holmes 1984). The latter is
53 often larger and anteroposteriorly wider than the intercentrum and supports the neural arch 54 (Panchen 1970), whereas the intercentrumDraft bears the articular facet for the capitulum of the rib. 55 This distinct vertebral morphology was named “embolomerous” by Cope (1884) and was once
56 thought to be diagnostic of the group. This has since been found not to be the case, leading to
57 confusion in both the taxonomic composition of the group, as well as the evolutionary
58 significance of this distinctive vertebral morphology (Panchen 1970). Watson (1926) later
59 suggested that because of their early occurrence in the fossil record and similarity to early
60 reptiles, embolomerous tetrapods might have been the link connecting osteolepiform
61 tetrapodomorph fish to later tetrapod descendants. However, since then embolomeres have more
62 widely been regarded as stem amniotes (Clack et al. 2017). Interestingly, Clack’s (2011)
63 description of an embolomere tail from the Middle Pennsylvanian-aged Five Points locality in
64 Ohio, indicated the presence of supraneural radials ⎼ a trait shared with taxa as primitive as
65 Devonian tetrapodomorph fish. This evidence, along with other studies (e.g., Laurin and Reisz
66 1997; 1999) questioned whether embolomeres occupy a such a derived position or should instead
67 be placed in a more basal position on the tetrapod lineage. This alternative hypothesis is also
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68 supported by a more recent analysis by Pardo et al. (2017), who suggested embolomeres should
69 be classified as stem tetrapods alongside colostieds and baphetids. Despite the uncertainty
70 surrounding their interrelationships, the long evolutionary history of embolomeres makes them
71 an important group for studying early phases of tetrapod evolution (Clack 2002, 2012).
72
73 Tetrapod discoveries at the Mississippian-aged Point Edward locality
74 The Point Edward locality is located on a peninsula opposite Sydney Harbour, on Cape
75 Breton Island, Nova Scotia, Canada (Fig. 1A and B). The locality exposes a section of the Point
76 Edward Formation, which pertains to the Upper Mississippian of the Carboniferous (Allen et al.,
77 2014). The first tetrapod remains described from the Point Edward locality, and of the Draft 78 formation in general, were collected in 1956 by a team led by Alfred Romer of the Museum of
79 Comparative Zoology, Harvard University (Sues et al. 2013). The impression of a tetrapod jaw,
80 MCZ 2772, was provisionally assigned to a new embolomerous tetrapod taxon, Pholiderpeton
81 (?) bretonensis Romer 1958. Some 15 years later, Donald Baird of Princeton University also
82 collected a lower jaw from the Point Edward locality. He was able to recognize it as the
83 counterpart to MCZ 2772 and the two pieces were reunited in the MCZ collections (Sues et al.
84 2013). In 1962, Baird described another skull fragment from the Point Edward locality,
85 attributing it to the stem tetrapod Spathicephalus pereger Baird 1962 (YPM-PU 17182). In 1968,
86 Baird further collected the articulated pectoral girdle and trunk region of a tetrapod (YPM VPPU
87 020100) deemed similar to Greererpeton burkemorani Romer 1969 (Sues et al. 2013) and a
88 clavicle of an embolomere (YPM-PU 17190; A. Mann pers. obs.), which Panchen (1970)
89 referred to Pholiderpeton (?) bretonensis; however, this material remains undescribed.
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90 Housed in the Canadian Museum of Nature, Aylmer, Quebec, Canada, is another
91 collection of disarticulated tetrapod remains found at the Point Edward locality by W. A. Bell of
92 the Geological Survey of Canada in 1915, CMN 10015. The exact location of this discovery is
93 unknown, although relocation attempts have been made by a team led by Hillary Maddin of
94 Carleton University. Despite being the first tetrapod material to be collected from Point Edward,
95 Bell’s collection has remained largely unstudied. It consists of disarticulated cranial and
96 postcranial elements preserved among over 110 separate pieces of matrix and isolated elements,
97 making it currently the most extensive collection of tetrapod remains known from Point Edward.
98 Although the matrix is all the same lithology, the separation of the blocks eliminates any
99 possibility of confidently associating the elements. The collection was prepared and illustrated in
100 1971 by the late Gary Bernacsek, but if Draftany manuscript on the material was written then, it could
101 not be found. The CMN collections card notes that the specimen was referred to ?Pholiderpeton
102 bretonense by Wann Langston, though no formal description to this effect could be found in the
103 literature. Holmes (1984) briefly suggested that because the specimen is of Mississippian age, it
104 is more likely to be a proterogyrinid embolomere than Pholiderpeton. No further analysis of this
105 material has taken place since.
106 Here we provide the first thorough description of Bell’s material. It is hoped that this
107 work will contribute to our understanding of Carboniferous tetrapod diversity in Nova Scotia,
108 and farther abroad, as information from new and previously collected material is compiled and
109 analyzed.
110
111 GEOLOGICAL CONTEXT
112
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113 The bones examined here were found in an eroded, ex situ horizon of freshwater
114 limestone from the Point Edward Formation of the Lower Mabou Group (Bell 1938).
115 Temporally, this pertains to the Arnsbergian of the Late Mississippian (Allen et al. 2014;
116 Waldron et al. 2017) (see Fig. 1C). The Point Edward Formation has been described previously
117 (e.g. Belt 1965; Belt 1968), but a detailed measured section of the formation has yet to be
118 published; however, a description was provided in a report by Mather et al. (1944), which was
119 also reproduced in a Nova Scotia field guide by Carroll et al. (1972) and is included here within
120 the Supplementary Information file.
121 The Point Edward Formation is the uppermost unit of the Windsor Group, exhibiting
122 beds predominantly alternating between argillaceous limestone and calcareous siltstone and shale
123 (Belt 1965; Carroll et al. 1972). There isDraft one layer of petroliferous limestone near the top of the
124 formation. The siltstone and shale layers are dusky-red and greenish-grey, occasionally including
125 very fine-grained and thinly-bedded sandstone intervals. The youngest layer is a fine-grained
126 sandstone bearing ripples and plant fossils (Carroll et al. 1972). Overall, the formation is
127 interpreted as having been deposited in a mixed fluvial and lacustrine environment (Belt 1968).
128 This suggests a varying deltaic environment where the shoreline was constantly transgressing
129 and regressing, leading to the growth and contraction of lakes (Belt 1968).
130
131 MATERIALS AND METHODS
132
133 CMN 10015 was collected by W. A. Bell of the Geological Survey of Canada in 1915 on
134 the beach along the eastern coast of Point Edward in the Sydney Harbour, north and west of the
135 town of Sydney, Cape Breton Island, Nova Scotia, Canada. It consists of disarticulated, partial
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136 cranial and postcranial elements preserved among 77 pieces of bone-containing matrix, 33
137 individually prepared bones, 6 latex peels, and 5 casts of various bones within the collection (see
138 Supplementary Information file Table S1). Here we propose the material included within
139 specimen CMN 10015 be divided into potentially taxonomically distinct subgroups, CMN
140 10015B and CMN 10015C. The remaining material, CMN 10015A, contains material of
141 uncertain taxonomic affinity. CMN 10015A and CMN 10015B are described separately below,
142 and CMN 10015C will be described in future works.
143 Analysis of CMN 10015 was conducted at CMN Natural Heritage Campus, Aylmer,
144 Quebec, Canada. Measurements were taken using manual calipers. Illustrations of the main
145 elements accompany the specimen, all of which were completed by Gary Bernacsek in 1971.
146 Photographs were taken using a Sony AlphaDraft ILCE 5000 camera with an F3.5 lens. Photos were
147 cropped and formatted into figures in Photoshop CS6 (Adobe, San Jose, CA). Illustrations were
148 scanned and formatted into figures also in Photoshop CS6.
149
150 Institutional abbreviations
151 CMN, Canadian Museum of Nature, Ottawa, ON, Canada; CMNH, Cleveland Museum of
152 Natural History, Cleveland, OH, USA; MCZ, Museum of Comparative Zoology, Harvard
153 University, Cambridge, MA, USA; YPM, Yale Peabody Museum of Natural History, New
154 Haven, CT, USA.
155
156 SYSTEMATIC PALEONTOLOGY
157 158 CLADE Tetrapodomorpha Ahlberg, 1991
159 SUBORDER Embolomeri Cope, 1884
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160
161 MATERIAL: CMN 10015A
162 LOCALITY AND HORIZON: Point Edward Formation, Lower Mabou Group, Sydney Basin, Cape
163 Breton Island, Nova Scotia, Canada (Crawford 1995). The specimen consists of material found
164 as beach float along the eastern coastline of Point Edward, located in the Sydney Harbour,
165 Sydney. All material was collected by W. A. Bell in 1915.
166 COMMENTS: The degree of preservation of the elements varies from complete to fragmentary.
167 Although there are several skull fragments included in CMN 10015A, there is no evidence of
168 lateral lines. CMN 10015A corresponds to at least two individuals, based on the presence of two
169 right ilia and two femora of different sizes. 170 Draft 171
172 DESCRIPTION
173
174 Cranial morphology
175 A right and left maxilla are present, but the left is much better preserved and is the
176 element described here (Fig. 2A and B). The preserved portion of the left maxilla is 8.5 cm in
177 length. The anterior portion of the maxilla is complete, however it appears to be incomplete
178 posteriorly, and a portion of the middle section is also missing. As in Proterogyrinus Romer
179 1970 or Calligenethlon Steen 1934, the maxilla is elongate anteroposteriorly but has an
180 extremely short dorsal lamina throughout its length (Carroll 1967). A slight dorsoventral
181 expansion is present in the anterior-to-mid portion of the maxilla, where it would support the
182 lacrimal along its posterior sloping margin. This shape is distinct from the maxilla known from
183 the larger embolomeres like ‘Eogyrinus’ attheyi Watson, 1926 (now Pholiderpeton scutigerum
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184 Huxley, 1869; Clack 1987) in which the maxilla is dorsoventrally deepest anteriorly, and tapers
185 evenly to its posterior end. Anterior to the expanded region, the maxilla tapers in height, ending
186 with a steeply sloping and slightly concave anterior margin, which forms the posterior border of
187 the external naris. The ventral margin of the maxilla is also curved convexly in the region of the
188 dorsal expansion. The bone ornamentation in this region comprises small deep pits that dissipate
189 posteriorly.
190 There are 30 teeth present on the maxilla. However, including those assumed to have
191 been present in the missing middle section, and assuming that in life, the more posteriorly placed
192 teeth would have been as tightly packed as the anteriorly placed teeth are, the maxilla preserves
193 approximately 58 tooth positions. A significantly smaller count of 45-47 tooth positions is
194 observed in the maxilla of ProterogyrinusDraft (Romer 1970), whereas those of Archeria crassidisca
195 Cope 1884 (Romer 1957) and Pholiderpeton (Clack 1987) preserve at least 50-54 (Holmes 1984,
196 1989; Clack 1987). Like Calligenethlon (Steen 1934), Archeria (Holmes 1989), and eogyrinids,
197 the maxillary teeth of CMN 10015A are peg-like and generally homodont, with only a slight
198 variation in height along the tooth row, ranging from 5mm in height anteriorly to 2mm in height
199 posteriorly. The shortest teeth appear to have been broken. The more posterior teeth resemble
200 those of Archeria (Romer 1957) in being less recurved with flatter distal surfaces. Similar tooth
201 morphology has also been described for Proterogyrinus (Romer 1970) and Pholiderpeton (Clack
202 1987). Tooth positions 3 and 4 bear teeth that are slightly larger than those in the rest of the
203 series; however, not as distinctly so as may be expected in a canine region. The tooth in position
204 10 is similarly large, as are those in positions 7 and 8 to a slightly lesser degree. Each tooth bears
205 longitudinal grooves at the base of its labial surface, which may be attributable to labyrinthine
206 infolding. Anteriorly in the tooth row, only a single groove is present on each tooth, but
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207 posteriorly as many as three are present. Similar grooves are known to occur on the teeth of
208 Pholiderpeton (Clack 1987).
209 Although the palate is not preserved, there are four large teeth present, likely palatal
210 tusks. Their morphology is similar to that of the teeth of the maxillary dentition, although they
211 are larger (about 14mm in total length), with wide bases. Like those of most embolomeres, the
212 tusks are recurved apically, but the apex never recurves beyond the posterior edge of the base of
213 the tusk. There are longitudinal grooves at the base of the tusks, but there is no evidence of a
214 bony rim around the basal surfaces as is typical of the tusks of most embolomeres. However, this
215 may have been lost due to poor preservation.
216 The nasals are extremely fragmentary and incompletely preserved on all margins, except
217 posteriorly, where they are likely completeDraft but obscured by the frontals (Fig. 2C-E). As
218 preserved, the nasals are flat and square, although they were likely more nearly rectangular when
219 complete. As in other embolomeres, the dorsal surface of the nasal displays small pits scattered
220 unevenly around the center of the bone, as well as shallow grooves that radiate outwards from
221 the center. In contrast to Archeria (Holmes 1989) and ‘Eogyrinus’Pholiderpeton (Clack 1987), in
222 which the nasals are transversely wider than the frontals throughout their entire length, the nasals
223 of CMN 10015A appear to remain the same width as the frontals throughout their preserved
224 length, although their incomplete preservation renders this assessment tentative.
225 The frontals overlap the nasals anteriorly and are incomplete posteriorly (Fig. 2C-E). The
226 contact between the frontals and the nasals slopes anteromedially toward the midline of the skull,
227 much like that in Palaeoherpeton decorum Watson, 1926 (Panchen 1964) and Proterogyrinus
228 (Holmes 1984), but not as drastically as that in Pholiderpeton (Clack 1987). The preserved
229 portions of the frontals are approximately rectangular in shape and possess obvious striated
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230 ornamentation that parallels the long axis of the bone. The frontals are incomplete along their
231 lateral and posterior margins, and as such, their contact with the surrounding elements of the
232 skull table remains unknown.
233 Only a nearly complete right parietal is preserved (Fig. 2H and I). Overall, it is a very
234 simple wedge shape, like that of Archeria (Holmes and Baird 2011). It is ornamented across its
235 entire surface with small and slightly elongated pits that become smaller anteriorly. Its lateral
236 edge remains articulated with parts of the broken intertemporal anteriorly and the supratemporal
237 posteriorly. The medial margin is relatively smooth and straight, except where incised by the
238 pineal foramen. The foramen is surrounded by a prominent rim and there is a shallow,
239 anteroposteriorly oriented depression immediately lateral to it. This set of traits was once thought
240 to be diagnostic of Proterogyrinus (HolmesDraft 1984), but a similar ridge surrounding the foramen
241 has been observed in Pteroplax cornutus Hancock and Atthey 1868 (Panchen 1970) and
242 Archeria (Holmes 1989). Like most embolomeres, the pineal foramen in CMN 10015A occurs
243 anterior to the midpoint of the parietal. Compared to the rest of the parietal, the size of the pineal
244 foramen does not appear to be outside the range observed in Proterogyrinus (Holmes 1984).
245 The intertemporal, as preserved, is ovoid in outline (Fig. 2H and I). Its medial contact
246 with the parietal and posterior contact with the supratemporal is preserved, whereas its lateral
247 margin is incomplete. The intertemporal meets the lateral edge of the parietal, just posterior to
248 the pineal foramen, as in most embolomeres. The intertemporal-supratemporal suture is
249 relatively straight but incompletely preserved laterally. The dorsal surface of the intertemporal is
250 ornamented similarly to the parietal, with slightly elongated pits along its medial margin.
251 Laterally, the pits become smaller and more nearly circular.
252 The supratemporal contacts the intertemporal anteriorly and the parietal medially (Fig.
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253 2H and I). Overall, anteriorly the supratemporal is rectangular in outline, but tapers to a point
254 posteriorly. It is incomplete laterally. It also possesses a parietal-like dermal ornamentation
255 composed of small pits. In contrast to Proterogyrinus (Holmes 1984) and Calligenethlon
256 (Holmes and Carroll 2010), the supratemporal does not incise the lateral margin of the parietal,
257 but rather contacts the parietal at a straight suture, continuous with that of parietal-intertemporal.
258 This feature is also figured in Pholiderpeton (Clack 1987), Palaeoherpeton (Panchen 1970), and
259 Archeria (Holmes and Baird 2011), but seems to be variable even between the right and left
260 parietals of individuals and so its taxonomic significance remains unclear.
261 A fragment of a left tabular is preserved in association with a smaller fragment of another
262 partial supratemporal (Fig. 2F and G). The contact margin between these elements is sloped
263 posteromedially, as in Proterogyrinus (HolmesDraft 1984). The medial surface of the tabular is
264 articulated with the fragmented lateral-most tip of the postparietal and, anteromedially the
265 tabular contacts an incomplete parietal. The latter contact is one of the diagnostic features of
266 embolomeres (Panchen 1970). The tabular is not complete enough to determine whether this
267 specimen retains biramous tabular horns, which is a common feature of most embolomeres
268 (Holmes 1984). As with the parietal, the tabular is ornamented with small, elongated pits.
269 Fragments of isolated left and right squamosals are present, exposed in medial view.
270 They are smooth, plate-like bones bearing ventrally diverging, V-shaped striations. There is no
271 evidence of lateral lines in either squamosal but given their fragmentary state, this could be due
272 to preservational bias.
273 Two parabasisphenoids are preserved in ventral view (Fig. 2J and K). In both, a robust
274 cultriform process extends anteriorly from the massive body of the parasphenoid portion of the
275 complex. Ventrally the cultriform process is narrow and expands dorsolaterally much like that of
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276 Proterogyrinus (Holmes 1984), forming a trough to receive the sphenethmoid, which is not
277 preserved in either specimen. The posterior portion of the parasphenoid is concave between
278 posterolaterally-oriented rounded ridges that project posteriorly. Although the bulk of the
279 basisphenoid is not visible in ventral view, as it would have rested dorsally on the parasphenoid
280 portion, the basipterygoid processes are visible as bulbous projections that extend out laterally on
281 either side of the base of the cultriform process. The articular surfaces appear to be broken.
282 Carotid foramina are not discernible in either specimen.
283
284 Axial skeleton
285 The vertebral centra preserved in CMN 10015A range in size from 0.8 cm to 3.0 cm in
286 diameter and occur in varying states of preservation.Draft As in most embolomeres, the elements are
287 disc-shaped (Fig. 3A and B), although several of the small crescentic intercentra are incomplete
288 dorsally (Fig. 3C and D), as in Proterogyrinus (Holmes 1984) and Eoherpeton watsoni Panchen
289 (Smithson 1985). It is possible that the incomplete (usually smaller) elements represent young
290 individuals, and dorsal ossification occurs later in ontogeny (Holmes 1984) but many of the
291 smallest intercentra are also complete dorsally, suggesting that the complete and incomplete
292 elements could represent differing morphologies within one individual, as seen is in
293 Calligenethlon (Godfrey et al. 1991), which is the only embolomere known that possesses both
294 complete and incomplete intercentra within a single series of presacral vertebrae. It is also
295 possible that more than one embolomere taxon is represented in CMN 10015A, and the two
296 morphologies represent separate taxa. Until additional information is available, we assume that
297 only one taxon is represented.
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298 Like Pholiderpeton (Clack 1987) and Archeria (Holmes 1989), the intercentra appear
299 rectangular in lateral view, and as in other embolomeres, are anteroposteriorly narrower than the
300 pleurocentra. The anterior surface is concave to receive the posterior convex surface of the
301 adjacent pleurocentrum, and the posterior surface of the intercentrum is convex to articulate with
302 the concave anterior surface of the succeeding pleurocentrum. A pair of articular facets occurs
303 about midway on the lateral margin of the intercentrum to receive the proximal head of the rib.
304 The pleurocentra in CMN 10015A are disc-shaped and morphologically similar to those
305 of Archeria (Holmes 1989) (Fig. 3C and D). Their anteroposterior length is greater than that of
306 an intercentrum of equivalent diameter and generally they display a smaller notochordal canal.
307 The anterior surface is concave, and the posterior surface is convex to articulate with
308 complementary surfaces of the adjacentDraft intercentra. Similar to the intercentra, the pleurocentra
309 are rectangular in lateral view. Unlike the horseshoe-shaped pleurocentra in Proterogyrinus
310 (Holmes 1984), the pleurocentra in CMN 10015A appear to be fully ossified dorsally with no
311 trace of a dorsal suture, like those attributed to Pholiderpeton (Clack 1987), Calligenethlon
312 (Carroll 1967), and Archeria (Holmes 1989). Each pleurocentrum possesses two dorsolateral
313 facets that support the neural arch. Some are taphonomically broken, and like the intercentra,
314 some could be interpreted as either ontogenetically or taxonomically distinct from the complete
315 elements.
316 The neural arches bear a close resemblance to those observed in Proterogyrinus (Holmes
317 1984) (Fig. 3E-H). Most of the preserved neural spines are taller with a much-reduced lateral
318 face. These resemble the more posterior trunk vertebrae of other embolomeres. Some preserve
319 large, well-developed supraneural canals. There are also some posteriorly-leaning spines, similar
320 to the posterior caudal vertebrae in Proterogyrinus (Holmes 1984), Pholiderpeton (Clack 1987)
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321 and other embolomeres. Based on the overall similarity to Proterogyrinus (Holmes 1984), the
322 posteriorly leaning spines are likely around vertebrae positions 48-50, based on the angle from
323 vertical and narrowness. However, none is as laterally gracile or posteriorly-leaning as those
324 figured as the posterior-most spines on the tails of Pholiderpeton (Clack 1987) or Archeria
325 (Holmes 1989). Some arches bear neural spines that are relatively short, with a broad lateral
326 surface. Comparison with other embolomeres suggests that they are from the anterior part of the
327 trunk, perhaps between positions 6-10.
328 The ribs included in CMN 10015A are broken or preserved only in dorsal or ventral view
329 (Fig. 3I and J). Like those of Proterogyrinus (Holmes 1984) and Pholiderpeton (Clack 1987) as
330 well as those of other early tetrapods, the ribs are bicipital and curve gently ventrally. The largest
331 rib is approximately 9.7 cm from the headDraft to tip. Proximally, the head is flat and flares
332 transversely where it would contact the intercentrum. Several ribs preserve a longitudinal groove
333 extending from the most proximal point of the head to the base of the neck. The distal surfaces
334 are generally featureless. The ribs appear to be distally circular or subcircular in cross section,
335 similar to those of most embolomeres. The more robust ribs are likely from the trunk region and
336 are of uniform width throughout their length. The shorter and narrower ribs are likely from
337 progressively more posterior parts of the trunk and generally only the heads and the most
338 proximal portion of the shaft are preserved.
339
340 Appendicular skeleton
341
342 Although three right ilia were illustrated by G. Bernacsek, only two of them could be
343 relocated. One is preserved in medial and the other in lateral view (the latter is shown in Figure
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344 3K and L). The third, missing right ilium was figured in medial view (Fig. 3M). Each ilium
345 consists of a ventrally expanded acetabular region and a posterodorsally directed blade separated
346 by a narrow neck. The specimen preserved in lateral view shows a ventrally flared portion
347 bearing an articulation for the pubis anteriorly and ischium posteriorly. The posterodorsally-
348 directed blade of the missing specimen supports a broad, rectangular dorsal iliac process
349 anteriorly (Fig. 3M); it is larger than the process seen in Archeria (Romer 1957) and
350 Proterogyrinus (Holmes 1984). The process is missing in the two other specimens, but the
351 broken edge indicates that comparable-sized dorsal processes were present in the same position
352 but were lost before preservation. The posterior iliac process extends posteriorly, creating an
353 acute angle between its ventral margin and the dorsal margin of the ventral expansion. This sharp
354 angle is similar to that observed in CalligenethlonDraft (Godfrey et al. 1991), but it retains the more
355 robust dorsal processes and general shape observed in Proterogyrinus (Holmes 1984) or
356 Archeria (Romer 1957). The remainder of the posterior iliac process is moderately broad and
357 blade-like with gentle striations running its length.
358 The remains of two femora are included in CMN 10015A, one right and one left. The
359 latter is preserved as an impression and has lost much detail other than the general outline, but
360 the right femur is relatively complete (Fig. 3N and O). Both femora appear to be
361 morphologically similar, but the impression is 1.3 cm longer than the right femur, indicating that
362 both are unlikely to be from the same individual. The overall shape of the femur is similar to that
363 of Archeria, and the shaft appears wider than that of Proterogyrinus (Holmes 1984). In CMN
364 10015A the shaft is 44% the width of the distal condyle, whereas in P. scheelei it is 33%
365 (Holmes 1984) and P. pancheni it is 36% (Smithson 1986). However, as both articular ends of
366 the femur are incomplete, this estimation is approximate. The dorsal surface of the femur is
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367 smooth and slightly concave proximally whereas the ventral surface is mostly obscured by a rod
368 glued to the element for support. The anterior condyle extends anteriorly at a greater angle than
369 the posterior condyle extends posteriorly, but neither flare as dramatically as those seen in
370 Calligenethlon (Steen 1934). As preserved, the anterior condyle extends further distally; this
371 feature is more similar to Archeria (Romer 1957) than other embolomeres.
372 We tentatively identify a left tibia in the included material (Fig. 3P and Q): the long,
373 gracile shaft appears to be most similar to comparable parts of the tibia of Proterogyrinus
374 (Holmes 1984). Like that of Proterogyrinus (Holmes 1984), the shaft is straight in lateral view,
375 and expands transversely at a gentle angle at the head and tip. In this specimen, both the
376 proximal and distal ends of the tibia are incomplete. There are faint traces of a cnemial crest,
377 though this is also incomplete proximally.Draft
378 An incomplete left fibula is included in CMN 10015A (Fig. 3R and S), with the proximal
379 end is missing. Like that of Proterogyrinus (Holmes 1984), the shaft is not rod-like, but rather is
380 somewhat hourglass-shaped with slightly concave medial and lateral margins. The distal end is
381 expanded mediolaterally to form the flat, fan-like shape typical of other embolomere fibulae (eg.
382 Holmes 1984; Romer 1957) . The distal margin is more rounded than in Proterogyrinus (Holmes
383 1984) and Archeria (Romer 1957), however, completeness of the surface would easily affect this
384 shape.
385 Several disarticulated phalangeal elements are included in CMN 10015A (Fig. 3T-W).
386 The more triangularly shaped elements may represent distal elements. In general, the flat
387 proximal and distal articular surfaces, and concave medial and lateral margins, in all but the
388 distal-most bones, are very similar to those seen in Proterogyrinus (Holmes 1984) and other
389 embolomeres. Generally, the bones are smooth, but there is some rugosity on the proximal and
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390 distal surfaces. There are some more elongated elements, which are likely derived from the more
391 proximal part of the manus or pes or might be from the metapodium.
392
393 Scales
394 Several isolated scales are preserved in CMN 10015A (Fig. 3X and Y). They are
395 elongated with sub-rounded tips, with outlines ranging from subrectangular to more nearly
396 teardrop-shaped. All the scales have smooth margins and are similar in size to those seen in
397 Pholiderpeton (Clack 1987) and Proterogyrinus (Holmes 1984).
398
399 SYSTEMATICDraft PALEONTOLOGY
400 FAMILY Proterogyrinidae Romer, 1970
401
402 MATERIAL: Incomplete left lower jaw (herein CMN 10015B).
403 LOCALITY AND HORIZON: Point Edward Formation, Lower Mabou Group, Sydney Basin, Cape
404 Breton Island, Nova Scotia, Canada (Crawford 1995).
405 COMMENTS: The overall jaw morphology of CMN 10015B is very similar to that described for
406 Proterogyrinus (Holmes 1984), including total length and straight ventral margin. The anterior
407 portion of the jaw is long and gracile, like Proterogyrinus, and the surangular crest, although
408 present, is not as steep as in Pholiderpeton. The estimated tooth count of 64 is greater than the
409 estimated 50 for Proterogyrinus, and the peg-like morphology with a slightly recurved apex is
410 similar to Proterogyrinus. At its tallest point, CMN 10015B would be approximately 10 mm
411 deeper than a Proterogyrinus jaw of similar length.
412
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413 Description of CMN 10015B
414 CMN 10015B is an incomplete left lower jaw, preserved in lateral view (Fig. 4). Based
415 on comparisons to Proterogyrinus and other embolomeres, it is likely missing only about 5 mm
416 of its anterior extremity. The exposed surface is weathered but nonetheless presents a slightly
417 convex morphology with surperficial ridges and striations. As preserved, the lower jaw is 160
418 mm in length, and at its greatest dorsoventral depth, estimated from the peak of the surangular
419 crest to the base of the angular, is 50 mm. It is approximately the same length as the lower jaw of
420 Proterogyrinus scheelei (Holmes 1984), but is more robust and deeper than that of both species
421 of Proterogyrinus. In P. scheelei and P. pancheni the subparallel dorsal and ventral margins of
422 the lower jaw diverge posteriorly at a small angle; in contrast, in CMN 10015B the margins
423 diverge more dramatically, and the jaw Draftis much deeper just anterior to the surangular crest (72%
424 of total jaw depth for CMN 10015B in contrast to 65% and 62% for that of P. scheelei and P.
425 pancheni, respectively). Posteriorly, CMN 10015B is 16% deeper than that of Proterogyrinus
426 (Holmes 1984). This robust morphology is due to a more robust surangular, angular, and
427 postsplenial, and is most consistent with the morphology seen in Pholiderpeton scutigerum
428 (Clack 1987). Unlike ?Pholiderpeton bretonense (Romer 1963), the dorsal margin in CMN
429 10015B features a strong surangular crest.
430 As in other embolomeres, the anterior-most 20 mm of the dorsal margin curves very
431 slightly dorsally. Like the relatively gracile lower jaws of Proterogyrinus (Holmes 1984) and
432 Eoherpeton (Smithson 1985), the ventral margin of the lower jaw in CMN 10015B is relatively
433 straight, in contrast to the more bowed ventral margin in the robust jaws of Pholiderpeton
434 scutigerum (Clack 1987) and Archeria (Holmes 1989). The posterior ventral margin is more like
435 that of Proterogyrinus (Holmes 1984) in that it slopes upward more abruptly than that of
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436 Pholiderpeton scutigerum (Clack 1987), but less dramatically so than that of ?Pholiderpeton
437 bretonense (Romer 1963).
438 The dentary is narrower dorsoventrally than that of Proterogyrinus (Holmes 1984). It
439 tapers posteriorly and joins the surangular at a vertical suture, similar to that seen in Archeria
440 (Holmes 1989), rather than tapering to a point posteriorly, as in Proterogyrinus (Homes 1984).
441 The dentition continues along the full length of the dentary until its contact with the surangular.
442 The approximately 64 tooth positions preserved here is significantly greater than the 58 tooth
443 positions estimated for the maxilla of CMN 10015A, further supporting the hypothesis that they
444 pertain to distinct taxa. The tooth count of CMN 10015B is also significantly higher than that
445 recorded for both Pholiderpeton (53 teeth; Clack 1987) and Proterogyrinus (estimated to have
446 had approximately 50 tooth positions; HolmesDraft 1984). The teeth are approximately equal in size
447 and similar in morphology. They are closely spaced and generally cylindrical at their bases,
448 tapering apically to a recurved point.
449 Only a small portion of the splenial is visible on the external surface of the lower jar (Fig.
450 4). The surface of the anterior-most portion of the jaw is poorly preserved, making it difficult to
451 determine exactly where along the margin of the dentary the splenial terminates. There are some
452 striations on portions of the lateral surface of the splenial, but not much of the surface is
453 preserved well.
454 The external surface of the angular is predominantly smooth, with weak, diffuse
455 horizontal striations (Fig. 4). The angular contacts the surangular from its posterior most tip to
456 the point of articulation between the angular, surangular, and dentary.
457 The surangular (Fig. 4) is large and irregularly shaped. Posteriorly, it is expanded
458 dorsoventrally, forming a large surangular crest, unlike in ?Pholiderpeton bretonense, which
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459 does not display any surangular crest (Romer 1963). The posterolateral surface is ornamented
460 with striations that radiate outward from the point of contact with the articular. The ventralmost
461 striations are oriented along the long axis of the bone, but the more dorsal striations extend
462 ventrally.
463 The articular (Fig. 4) is incompletely preserved posterodorsally, and much of the surface
464 has also been lost. The surface that is preserved is similar to the surangular in that it is mostly
465 smooth, with some striations that are oriented with the long axis of the bone.
466 The postsplenial is extensive, originating where the surangular crest begins, and
467 continuing until it contacts the dentary at its anteriormost margin. A deep groove runs along the
468 ventral surface of the postsplenial, parallel to the medial line of the bone, and tapers just anterior
469 to the distal-most boundary of the bone.Draft Like many of the other bones of the lower jaw, the
470 postsplenial is ornamented with horizontal striations running the length of the bone.
471
472
473 DISCUSSION
474
475 Embolomere diversity of the Point Edward locality
476 Detailed analysis of CMN 10015 reveals that Bell’s material, although the most complete
477 tetrapod specimen from Point Edward, does not preserve any unambiguously diagnostic
478 characteristics that pertain to any one embolomere taxon. This suggests that either the material
479 represents a new genus and species diagnosed by a unique combination of traits or that multiple
480 taxa are represented.
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481 CMN 10015A cannot be assigned to any currently known genus of embolomere. There
482 are at least two individuals present, based on the preservation of two right ilia and two femora of
483 different lengths. All elements display a general similarity in morphology and size to those of
484 Proterogyrinus, with the exception of the fully circular vertebral elements. As such, this material
485 likely represents the first record of a proterogyrinid at the Point Edward locality. It is possible
486 that at least some elements in CMN 10015A pertain to the taxon represented by CMN 10015B. If
487 so, we suggest that a proterogyrinid, possibly Proterogyrinus, is present at Point Edward.
488 However, the lower jaw in CMN 10015B possesses some differences to the lower jaw of known
489 species of Proterogyrinus (Holmes 1984), the most obvious being a greater dorsoventral depth
490 and a higher tooth count. The overall length of the lower jaw of CMN 10015B is roughly the
491 same as that of Proterogyrinus, suggestingDraft that the difference in depth and tooth count are likely
492 not due to ontogeny. We suggest that although this jaw pertains to Proterogyrinidae, it cannot be
493 assigned to either known species of Proterogyrinus. Until a more detailed understanding of
494 variation in taxonomically significant traits in embolomeres is obtained, formal referral of the
495 material to lower-level taxa (new or previously known) is not recommended. Furthermore,
496 because all the material is currently distributed among many separate blocks, and that the
497 original spatial context of the material is lost, taphonomic association cannot be distinguished
498 from taxonomic association.
499 The presence of two distinct lower jaw specimens (CMN 10015B and CMN 10015C) is
500 consistent with the presence of at least two taxa at the Point Edward locality. The robust, anterior
501 jaw fragment (CMN 10015C) displays very different morphology from CMN 10015B and
502 therefore represents further diversity at this site. Although more detailed work is being done on
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503 CMN 10015C to describe its morphology and clarify its taxonomic identity, at the moment the
504 anatomical information is too limited to do more than separate it from CMN10015A and B.
505
506 Vertebrate Fauna of the Point Edward locality
507 The major constituents of most Middle to Late Mississippian Carboniferous tetrapod
508 localities are large, aquatic stem-tetrapods such as baphetids, colosteids, whacheeriids, and
509 embolomeres (Garcia et al. 2006). While presenting new data on the similarly-aged Namurian
510 Hancock County tetrapod locality, Garcia et al. (2006) summarized clade level vertebrate faunal
511 comparisons among Late Mississippian localities. In their discussion, Garcia et al. (2006) briefly
512 summarize the Point Edward vertebrate fauna and note similarities to that of other Early to
513 Middle Mississippian localities includingDraft local faunas from Greer (West Virginia), Goreville
514 (Illinois), Delta (Iowa), and Hancock County (Kentucky), particularly in the presence of large
515 tetrapodomorphs and fishes present. Our current survey of the Point Edward fauna generally
516 agrees with these prior interpretations for this locality, and additionally provides updated records
517 including new taxonomic diversity.
518 Embolomeres in particular remain an important faunal component throughout the
519 Pennsylvanian and Early Permian ecosystems, often serving as the largest aquatic predators.
520 Although embolomere material has been reported from horizons dating as early as ‘Romer’s
521 Gap’ during the Early Mississippian at Blue Beach, Nova Scotia (Anderson et al. 2015),
522 embolomeres are more completely known from Late Carboniferous localities, appearing in a
523 relatively higher abundance at sites similar in age to Point Edward (Holmes 1984; Garcia et al.
524 2006). Embolomere remains from North America are rare, and the occurrence of more than one
525 taxon at one locality is unusual but not unknown; for example, the Middle Pennsylvanian-aged
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526 Linton locality in Ohio preserves specimens referable to two embolomere taxa (Holmes and
527 Baird 2011). Our findings suggest that the Point Edward local fauna includes at least two
528 embolomere taxa, and possibly more.
529 In addition to these embolomere taxa, the Point Edward local fauna also documents other
530 large-bodied stem tetrapod taxa, including the baphetid Spathicephalus pereger (Baird 1962) and
531 a colosteid similar to Greererpeton burkemorani (Sues et al. 2013). All of these tetrapodomorphs
532 were large, heavily built aquatic predators. Baird (1962) also noted fish material that had been
533 collected from the same layer as the jaw of ?Pholiderpeton bretonense, including a gyracanth
534 spine, a quadrate originally attributed to Sagenodus Owen, 1867 (although this identification
535 may be incorrect, J.A. Clack, pers. comm.), and teeth of Ctenoptychius cristatus Dawson, 1868
536 (Carpenter et al. 2015), as well as variousDraft other fragmentary fish remains, all of which typically
537 occur within Carboniferous freshwater assemblages (Baird 1978; Carpenter et al. 2015). The
538 fossils from the Point Edward locality occur in a very fine-grained freshwater limestone rich in
539 ostracods (Baird 1962), indicative of a low energy freshwater aquatic environment, such as a
540 lake. Recent fieldwork at this locality has recovered abundant gyracanth fin spines and other fish
541 fossils, but minimal new tetrapod material (pers. obs. A. Mann and H.C. Maddin), and of these,
542 none are considered primarily adapted to terrestrial environments.
543
544
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545 ACKNOWLEDGEMENTS
546 Many thanks go to Dr. Robert Holmes whose documentation and consolidation of all the
547 previous work done on Bell’s collection made this project possible, and Gary Bernacsek for the
548 illustrations. Thank you to Jordan Mallon, Margaret Currie, John Matlock Hargrove and all the
549 staff at the CMN Collections Facility for access to the specimen. Many thanks go to the
550 knowledgeable reviewers for providing helpful insights and suggestions that improved this
551 manuscript. Thank you also to Nabil Shawwa and the Maddin Lab for discussion and advice.
552
553 Draft
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554 REFERENCES
555 Ahlberg, P.E. 1991. A re-examination of sarcopterygian interrelationships, with special reference
556 to the Porolepiformes. Zoological Journal of the Linnean Society, 103: 241–287.
557
558 Allen, J.P., Fielding, C.R., Gibling, M.R., and Rygel, M.C. 2014. Recognizing products of
559 palaeoclimate fluctuation in the fluvial stratigraphic record: an example from the Pennsylvanian
560 to Lower Permian of Cape Breton Island, Nova Scotia. Sedimentology, 61: 1332–1382.
561
562 Anderson, J.S., Smithson, T., Mansky, C.F., Meyer, T., and Clack, J. 2015. A diverse tetrapod
563 fauna at the base of ‘Romer’s Gap’. PLoS ONE: 1932–6203.
564 Baird, D. 1962. A rhachitomous amphibian,Draft Spathicephalus from the Mississipian of Nova
565 Scotia. Zoology, Brevoria, 157: 9.
566
567 Baird, D. 1978. Studies on Carboniferous freshwater fishes. American Museum Novitates, 2641.
568
569 Bell, W.A. 1938. Fossil flora of Sydney Coalfield, Nova Scotia. Geological Survey of Canada
570 Memoir, 215: 12.
571
572 Belt, E.S., 1965. Stratigraphy and paleogeography of Mabou Group and related middle
573 Carboniferous facies, Nova Scotia, Canada. Geological Society of America Bulletin, 76: 777–
574 802.
575
26 https://mc06.manuscriptcentral.com/cjes-pubs Page 27 of 38 Canadian Journal of Earth Sciences
576 Belt, E.S., 1968. Carboniferous continental sedimentation, Atlantic provinces, Canada. Special
577 Papers – Geological Society of America, 106: 127.
578
579 Carpenter, D.K., Falcon-Lang, H.J., Benton, M.J., and Grey, M. 2015. Early Pennsylvanian
580 (Lansettian) fish assemblages from the Joggins Formation, Canada, and their implications for
581 palaeoecology and palaeogeography. Palaeontology, 58: 661–690.
582
583 Carroll, R.L. 1967. Labyrinthodonts from the Joggins Formation. Journal of Paleontology, 41:
584 111-142.
585
586 Carroll, R.L., Belt, E.S., Dineley, D.L., DraftBaird, D., and McGregor, D.C. 1972. Vertebrate
587 Paleontology of Eastern Canada: Excursion A59. XXIV International Geological Congress Field
588 Guide. D. J. Glass, Calgary.
589
590 Clack, J.A. 1987. Pholiderpeton scutigerum Huxley, an amphibian from the Yorkshire coal
591 measures. Philosophical Transactions of the Royal Society of London, 318: 1–107.
592
593 Clack, J.A. 2002. An early tetrapod from ‘Romer’s Gap’. Nature, 418: 72.
594
595 Clack, J.A. 2011. A Carboniferous embolomere tail with supraneural radials. Journal of
596 Vertebrate Paleontology, 31: 1150–1153.
597
598 Clack, J.A. 2012. Gaining Ground. Indiana University Press, Bloomington, Indiana.
27 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 28 of 38
599
600 Clack, J.A., Bennett, C.E., Carpenter, D.K., Davies, S.J., Fraser, N.C., Kearsey, T.I., Marshall,
601 J.E., Millward, D., Otoo, B.K., Reeves, E.J. and Ross, A.J. 2017. Phylogenetic and
602 environmental context of a Tournaisian tetrapod fauna. Nature ecology & evolution, 1(1),
603 p.0002.
604
605 Cope, E.D. 1884. The Batrachia of the Permian period of North America. The American
606 Naturalist, 18: 26–39.
607 608 Crawford, T.L. 1995. Carbonates and associatedDraft sedimentary rocks of the Upper Visean to 609 Namurian Mabou Group, Cape Breton Island, Nova Scotia: evidence for lacustrine deposition.
610 Atlantic Geology, 31: 167–182.
611
612 Godfrey, S.J., Holmes, R.B., and Laurin, M. 1991. Articulated remains of a Pennsylvanian
613 embolomere (Amphibia: Anthracosauria) from Joggins, Nova Scotia. Journal of Vertebrate
614 Paleontology, 11: 213–219.
615
616 Garcia, W.J., Storrs, G.W., and Greb, S.F. 2006. The Hancock County tetrapod locality: a new
617 Mississippian (Chesterian) wetlands fauna from western Kentucky (USA). In Wetlands throught
618 Time. Edited by S.R. Greb, and W.A. DiMichele. Geological Society of America, Boulder,
619 Colorado. pp. 155-168.
620
28 https://mc06.manuscriptcentral.com/cjes-pubs Page 29 of 38 Canadian Journal of Earth Sciences
621 Holmes, R.B. 1984. The Carboniferous amphibian Proterogyrinus scheelei Romer, and the early
622 evolution of tetrapods. Philosophical Transactions of the Royal Society of London, 306: 431–
623 527.
624
625 Holmes, R.B. 1989. Skull and axial skeleton of the Lower Permian anthracosauroid amphibian
626 Archeria crassidisca Cope. Palaeontographica, 207: 161–206.
627
628 Holmes, R.B., and Baird, D. 2011. The smaller embolomerous amphibians (Anthracosauria)
629 from the Middle Pennsylvanian (Desmoinesian) localities at Linton and five points coal mines,
630 Ohio. Breviora, 41: 1–13.
631 Draft
632 Holmes, R.B., and Carroll, R.L. 2010. An articulated embolomere skeleton (Amphibia:
633 Anthracosauria), from the Lower Pennsylvanian (Bashkirian) of Nova Scotia. Canadian Journal
634 of Earth Sciences, 47: 209–219.
635
636 Laurin, M., and Reisz, R.R. 1997. A new perspective on tetrapod phylogeny. In Amniote
637 origins—completing the transition to land. Edited by S. Sumida and K. Martin. Academic Press,
638 London, pp. 9–59.
639
640 Laurin, M. and Reisz, R. R. 1999. A new study of Solenodonsaurus janenschi, and a
641 reconsideration of amniote origins and stegocephalian evolution. Canadian Journal of Earth
642 Sciences, 36: 1239–1255.
643
29 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 30 of 38
644 Mather, K.F., Tullis, E.L., and Beck, C.W. 1944. Petroleum geology of the Sydney area, Cape
645 Breton Island, Nova Scotia. A report prepared for the Sydney Petroleum Company, 15 Congress
646 Street, Boston, MA, pp. 30.
647
648 Panchen, A.L. 1964. The cranial anatomy of two coal measure anthracosaurs. Philosophical
649 Transactions of the Royal Society, 242: 593–637.
650
651 Panchen, A.L. 1970. Handbuch der Paläoherpetologie, Teil 5a - Anthracosauria. Stuttgart, G.
652 Fischer.
653
654 Panchen, A.L. 1972. The skull and skeletonDraft of Eogyrinus attheyi Watson (Amphibia:
655 Labyrinthodontia). Philosophical Transactions of the Royal Society of London, 263: 279–326.
656
657 Panchen, A.L. 1977. On Anthracosaurus russelli Huxley (Amphibia: Labyrinthodontia) and the
658 family Anthracosauridae. Philosophical Transactions of the Royal Society of London. B,
659 Biological Sciences, 279: 447-512.
660
661 Pardo, J.D., Szostakiwskyj, M., Ahlberg, P.E., and Anderson, J.S. 2017. Hidden morphological
662 diversity among early tetrapods. Nature, 546: 642–645.
663
664 Romer, A.S. 1957. The appendicular skeleton of the Permian embolomerous amphibian
665 Archeria. Contributions of the Museum of Geology, University of Michigan, 13: 103–159.
666
30 https://mc06.manuscriptcentral.com/cjes-pubs Page 31 of 38 Canadian Journal of Earth Sciences
667 Romer, A.S. 1958. An embolomere jaw from the Mid-Carboniferous of Nova Scotia. Breviora,
668 87: 1–8.
669
670 Romer, A.S. 1963. The larger embolomerous amphibians of the American Carboniferous.
671 Bulletin of the Museum of Comparative Zoology at Harvard, 128: 415–454.
672
673 Romer, A.S. 1970. A new anthracosaur labyrinthodont Proterogyrinus scheelei, from the Lower
674 Carboniferous. Kirtlandia, 10: 1–16.
675
676 Smithson, T.R. 1985. The morphology and relationships of the Carboniferous amphibian
677 Eoherpeton watsoni Panchen. ZoologicalDraft Journal of the Linnean Society, 85: 317–410.
678
679 Smithson, T.R. 1986. A new anthracosaur amphibian from the Carboniferous of Scotland.
680 Palaeontology, 29: 603–628.
681
682 Sues, H.D., Hook, R.W., and Olsen, P.E. 2013. Donald Baird and his discoveries of
683 Carboniferous and early Mesozoic vertebrates in Nova Scotia. Atlantic Geology, 49: 90–103.
684
685 Waldron, J.W.F, Giles, P.S., and Thomas, A.K. 2017. Correlation chart for Late Devonian to
686 Permian stratified rocks of the Maritimes Basin, Atlantic Canada. Nova Scotia Department of
687 Energy Open File Report 2017-02.
688
31 https://mc06.manuscriptcentral.com/cjes-pubs Canadian Journal of Earth Sciences Page 32 of 38
689 Watson, D.M.S. 1926. Croonian lecture. The evolution and origin of the Amphibia.
690 Philosophical Transactions of the Royal Society, 214: 189–257.
691 692
Draft
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693 FIGURE CAPTIONS 694 695 Figure 1: Map and geologic cross section of the Point Edward Formation. A, Map of Canada
696 indicating the location of the province of Nova Scotia (dark grey). B, Close up of Nova Scotia,
697 Canada (dark grey) with Cape Breton Island indicated in light grey. C, Close up of Cape Breton
698 Island (inset from A) showing the location of the Point Edward locality. Map data: Google,
699 DigitalGlobe. D, Stratigraphic context of the Point Edward Formation, which is exposed at the
700 Point Edward locality, where ‘P.’ is the geological period and ‘Gp.’ is lithological group
701 (modified from Waldron et al. 2017).
702
703 Figure 2: Cranial elements of CMN 10015A. A-B, photo and line drawing of the left maxilla in
704 lateral view. C-E, photo and line drawingDraft of the frontals (f) and nasals (n) in dorsal view,
705 anterior is to the top. F-G, photo and line drawing of an incomplete skull table, including a right
706 parietal (p), intertemporal (it) and supratemporal (st) in dorsal view, anterior is to the top. H-I,
707 photo and line drawing of an incomplete skull table, including supratemporal (st), tabular (tab),
708 parietal (p), and postparietal (pp) in dorsal view. J-K, photo and line drawing of the braincase in
709 ventral view. Illustrations by G. Bernacsek. Scale bars equal 1 cm.
710
711 Figure 3: The postcranial elements of CMN 10015A. A-B, photo and line drawing of the
712 intercentrum in posterior view. C-D, photo and line drawing of the pleurocentrum in anterior
713 view. E-F, photo and line drawing of a neural spine showing well-developed supraneural arches
714 in anterior view. G-H, photo and line drawing of a caudal neural spine in right lateral view. I-J,
715 photo and line drawing of a rib fragment in lateral view. K-L, photo and line drawing of the right
716 ilium in medial view. M, line drawing of a second right ilium in medial view, scale unknown.
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717 (Figured by G. Bernacsek but the specimen was not able to be located in CMN 10015A). N-O,
718 photo and line drawing of a right femur in dorsal view. P-Q, photo and line drawing of a left
719 tibia in lateral view. R-S, photo and line drawing of the left fibula in dorsal view. T-W, photos
720 and line drawings of various disarticulated phalanges. X-Y, photo and line drawing of a scale in
721 dorsal view. Illustrations by G. Bernacsek. Scale bars equal 1 cm.
722
723 Figure 4: Left lower jaw of CMN 10015B. A-B, photo and line drawing of the lower jaw
724 preserving the angular (a), articular (art), dentary (d), splenial (spl), postsplenial (pspl), and
725 surangular (sa), in lateral view. Illustration by G. Bernacsek. Scale bar equals 1 cm.
726
727 Draft
728
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Draft
Figure 1: Map and geologic cross section of the Point Edward Formation. A, Map of Canada indicating the location of the province of Nova Scotia (dark grey). B, Close up of Nova Scotia, Canada (dark grey) with Cape Breton Island indicated in light grey. C, Close up of Cape Breton Island (inset from A) showing the location of the Point Edward locality. Map data: Google, DigitalGlobe. D, Stratigraphic context of the Point Edward Formation, which is exposed at the Point Edward locality, where ‘P.’ is the geological period and ‘Gp.’ is lithological group (modified with permission from Waldron et al. 2017).
127x425mm (300 x 300 DPI)
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Draft
Cranial elements of CMN 10015A. A-B, photo and line drawing of the left maxilla in lateral view. C-E, photo and line drawing of the frontals (f) and nasals (n) in dorsal view, anterior is to the top. F-G, photo and line drawing of an incomplete skull table, including a right parietal (p), intertemporal (it) and supratemporal (st) in dorsal view, anterior is to the top. H-I, photo and line drawing of an incomplete skull table, including supratemporal (st), tabular (tab), parietal (p), and postparietal (pp) in dorsal view. J-K, photo and line drawing of the braincase in ventral view. Illustrations by G. Bernacsek. Scale bars equal 1 cm.
203x255mm (300 x 300 DPI)
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The postcranial elements of CMN 10015A. A-B, photo and line drawing of the intercentrum in posterior view. C-D, photo and line drawing of the pleurocentrum in anterior view. E-F, photo and line drawing of a neural spine showing well-developed supraneural arches in anterior view. G-H, photo and line drawing of a caudal neural spine in right lateral view. I-J, photo and line drawing of a rib fragment in lateral view. K-L, photo and line drawing of the right ilium in medial view. M, line drawing of a second right ilium in medial view, scale unknown. (Figured by G. Bernacsek but the specimen was not able to be located in CMN 10015A). N- O, photo and line drawing of a right femur in dorsal view. P-Q, photo and line drawing of a left tibia in lateral view. R-S, photo and line drawing of the left fibula in dorsal view. T-W, photos and line drawings of various disarticulated phalanges. X-Y, photo and line drawing of a scale in dorsal view. Illustrations by G. Bernacsek. Scale bars equal 1 cm.
203x279mm (300 x 300 DPI)
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Left lower jaw of CMN 10015B. A-B, photo and line drawing of the lower jaw preserving the angular (a), articular (art), dentary (d), splenial (spl), postsplenial (pspl), and surangular (sa), in lateral view. Illustration by G. Bernacsek. Scale bar equals 1 cm.
203x166mm (300 x 300 DPI)
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