Steneofiber depereti Mayet, 1908
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publication ID |
https://doi.org/ 10.4202/app.00997.2022 |
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persistent identifier |
https://treatment.plazi.org/id/3362878F-FFD3-D230-8389-9E373926FE55 |
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treatment provided by |
Felipe |
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scientific name |
Steneofiber depereti Mayet, 1908 |
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Steneofiber depereti Mayet, 1908
Figs. 2–6 View Fig View Fig View Fig View Fig .
For synonymy see Hugueney (1999).
Material.— Hammerschmiede locality, Germany, lower Upper Miocene, MN 7 /8, base of Tortonian, for measurements see Tables 1 and 2). HAM 5, upper dentition: left I2: GPIT /MA/10749; right I2: GPIT /MA/10753; left DP4: GPIT / MA/10744, 10781; left P4: GPIT /MA/10746; left M1/2: GPIT / MA/10731, 13820; right M1/2: GPIT /MA/12604, 13825; left M3: GPIT /MA/10748, 12152. HAM 5, lower dentition: left i2: GPIT /MA/10743; right i2: GPIT /MA/10729; left dp4: GPIT /MA/10782; right dp4: GPIT /MA/10785, 13826; left p4: GPIT /MA/09896, 10727, 13980, SNSB-BSPG 2020 XCV-0303; right p4: GPIT /MA/10745; left m1/2: GPIT / MA/09897, 09902, 09906, 10728, 10784, 12342, 13822, 13824; right m1/2: GPIT /MA/09903, 12032, 12260, 13821; right m3: GPIT /MA/09907, 10751, 13823; right mandible with angular process, part of the coronoid process, i2 and m1: GPIT /MA/13813; right mandible with angular process, p4, m1 and m3: GPIT /MA/09909; right mandible (frag.) with i2: GPIT /MA/10742. HAM 4, upper dentition: right I2: GPIT /MA/17456, 17807, SNSB-BSPG 2020 XCIV-0661 ; left DP4: GPIT /MA/12416, 12489; right DP4: GPIT / MA/17763, SNSB-BSPG 2020 XCIV-0879 , 1731 ; left P4: GPIT /MA/17205, 10989, SNSB-BSPG 2020 XCIV-1725 , 3891 , 5375 ; right P4: GPIT /MA/17422, 17772, 16935, 17081, SNSB-BSPG 2020 XCIV-1510 ; left M1/2: GPIT /MA/16755, 12490, 16134, SNSB-BSPG 2020 XCIV-1724 , 5366 , 5371 ; right M1/2: GPIT /MA/17358, 16845, SNSB-BSPG 2020 XCIV-1391 , 1726 , 1727 , 4059 , 5367 , 5368 , 5369 , 5370 , 5372 , 5374 , 5376 , 5377 , 5378 ; left M3: GPIT /MA/12562, 16530, SNSB-BSPG 2020 XCIV-0415 , 1320 , 1728 , 1729 ; right M3: GPIT /MA/10990, SNSB-BSPG 2020 XCIV-0446 , 1730 , 3388 , 5373 ; maxillae and palatine (frag.) with left P4–M1 and right P4: GPIT /MA/17163; right P4–M2 (frag.): GPIT / MA/17367; left maxilla (frag.) with P4: GPIT /MA/16979. HAM 4, lower dentition: left i2: GPIT /MA/16985, SNSB-BSPG 2020 XCIV-1100 ; right i2: GPIT /MA/16512, 16928, 16436; left dp4: SNSB-BSPG 2020 XCIV-5365 ; left p4: GPIT /MA/17296, 17352, SNSB-BSPG 2020 XCIV-0179 , 0487 , 1246 , 3726 ; right p4: GPIT /MA/18113, SNSB-BSPG 2020 XCIV-2276 , 5362 ; left m1/2: GPIT /MA/16908, SNSB-BSPG 2020 XCIV-3572 , 3745 , 5359 , 5363 , 5364 ; right m1/2: GPIT /MA/10987, 16672, 16915, SNSB-BSPG 2020 XCIV-1185 , 1468 , 1723 , 3903 , 5357 , 5358 , 5360 ; left m3: GPIT / MA/17388, SNSB-BSPG 2020 XCIV-0416 , 1114 , 1719 , 5361 ; right m3: GPIT /MA/17666, SNSB-BSPG 2020 XCIV-1720 , 1721 , 1722 ; left mandible with i2, dp4, m1, m2 (juvenile): GPIT /MA/17569; left mandible with dp4, m1, m2, m 3 juvenile): GPIT /MA/16950; left mandible with i2 (frag.), p4 (frag.), m1, m2: GPIT /MA/17068; left mandible with p4, m1, m2: SNSB-BSPG 2020 XCIV-1494 ; right mandible with p4 (frag.), m1, m2: GPIT /MA/16839; right mandible
(frag.) with m2, m3: GPIT/MA/17280; left mandible (frag) with m1: GPIT/MA/18106; right mandible (frag.) with m2: SNSB-BSPG 2020 XCIV-2134; left angular process: GPIT/ MA/16586; right angular process: GPIT/MA/17215.
Description.—In general, all cheek teeth are subhypsodont to hypsodont, developing complete and closed roots with age. Hypostriid and hypostria are always the longest striid/ stria, but they never extend to the crown base although they can get quite close to it in the lower premolars. Mesostriid/-ia are usually longer than para- and metastriid/-stria, with the latter always terminating within the first quarter of tooth crown. The premolar is the largest tooth of the cheek teeth. Flexus/-ids, fossettes/-ids and striae/striids are gradually filled with cement with increasing wear stages and age.
Upper dentition: GPIT/MA/17163 is the most complete specimen with parts of the maxillae and palatine including both P4, the left M1 and the alveoli of all other molars. Another maxilla fragment (GPIT/MA/16979) consists of a left P4 ( Fig. 2 View Fig ). GPIT/MA/17367 comprises a right P4, M1 and M2; however, the remains of the maxilla were too weathered to be rescued. The rest of the material of the upper dentition is represented by isolated teeth; in total, five I2 fragments, seven DP4, 15 P4 (three in situ), 28 M1/2 (three in situ) and 13 M3.
I2: Five upper incisor fragments were excavated, all with their tips preserved. Their wear facets are all terraced and divided into two different parts. The labial tooth surface shows a smooth enamel band. A sharp and steep anterior tip consisting of mostly the labial enamel band and the angled lingual part of the dentine shows small and irregularly stepped wear marks parallel to the enamel band. The cross section of the upper incisor depicts an equilateral triangle with slightly convex sides (Reuleaux triangle). The lingual tip of this triangle is directed mesially.
DP4: All seven DP4 are worn and their para- and metafossettes are clearly visible ( Figs. 3A–E View Fig , 4A, B), but only in four specimens an open mesoflexus is exposed ( Figs. 3A–D View Fig , 4A, B). GPIT /MA/10781 is the most worn DP4 and its mesoflexus is closing ( Fig. 3E View Fig ). In all DP4 the hypoflexus/-stria are still open and do not reach the base of the crown ( Figs. 3A–E View Fig , 4A, B 1). Two DP 4 show an additional small fossette, one laterally to the parafossette ( GPIT / MA/10744; Figs. 3D View Fig , 4A) and one between parafossette and mesoflexus ( GPIT /MA/12416; Fig. 3A View Fig ). Synclines of DP4 are never filled with cement. Only two DP4 have their entire base preserved ( GPIT /MA/10744 and 17763) that consists of three roots with two small uniform buccal roots and one large dominant lingual root (Fig. 4B 1, B 2) .
P4: In general, the occlusal surface of the P4 is nearly as wide as long ( Figs. 3F–P View Fig , 4C–F). Mesiolingually the P4 is rounded, whereas the posterior and buccal margins are straight, forming an angular edge. The hypostria always closes well above the tooth base (Fig. 4D 2, E 2, F). Striae, flexus and fossettes of all P4 are at least slightly filled with cement in the least worn specimens (SNSB-BSPG 2020 XCIV-1510 and 3891; Figs. 3F View Fig , 4C) and cement filling increases with wear and age. The P4 is double-rooted with one minor root located at the distobuccal edge (Fig. 4D 3). The dominant root forms a wide arch that follows the mesiolingual tooth margin. The least worn P4 (SNSB-BSPG 2020 XCIV-1510) is the only unrooted P4 consisting of the tooth crown solely.
Only in the least worn SNSB-BSPG 2020 XCIV-3891 a metaflexid and a tiny enamel stylid at the buccal margin are expressed, but near to closure ( Figs. 3G View Fig , 4C). All other available P4 are worn and the metafossette is exposed ( Fig. 3G–P View Fig ). Their para- and mesostria are very short or in higher wear stages they are already closed as fossettes ( Figs. 3H–P View Fig , 4D–F) .
On the buccal side, the least worn teeth (GPIT/MA/17422 and SNSB-BSPG 2020 XCIV-1510) show a longer parastria and shorter mesostria ( Fig. 3G View Fig ). In contrast, similarly worn GPIT/MA/10989, 17367, and 17772 show an already closed parastria (parafossette) and an open and therefore longer mesostria ( Figs. 3H, I View Fig , 4D 3).
In occlusal view, the length of the hypoflexus is slightly shorter than the paraflexus, but both are curved mesially and almost meet lingually to the centre of the tooth ( Figs. 3F–P View Fig , 4C, D 1, E 1, F 1).
The hypoflexus and paraflexus/fossette are highly variable. In five specimens they meet facing in a straight line ( GPIT /MA/17772, 17422, 17163, SNSB-BSPG 2020 XCIV-3891 and 5375) ( Figs. 3F–I View Fig , 4C). In contrast, five other specimens show a different pattern. In three of those teeth the curved ending of the paraflexus/fossette is oriented mesially to the hypoflexus ( GPIT /MA/16935, 17081, and 10989), whereas in the two other teeth they are situated distally to the hypoflexus ( GPIT /MA/10746 and SNSB-BSPG 2020 XCIV-1725 ). In general, the mesoflexus/fossette of the P4 is curved and elongated far to the posterior occlusal tooth margin. The metafossette is encompassed by the mesoflexus/fossette and relatively short. In the deeply worn GPIT / MA/10746 para- and mesofossette are more irregular and wavier in shape ( Fig. 3P View Fig ) .
Only in one specimen with both P4s ( GPIT /MA/17163) in situ, two additional fossettes are exposed. The smaller fossette is situated in between the hypoflexus and the mesofossette and the larger one is located in the distolingual corner and perpendicular to the lingual ends of the para-, meso-, and metafossette as well as the hypoflexus ( Figs. 2A View Fig 1 View Fig , 3L, M View Fig ) .
M1/2: The occlusal outline of upper M1/2 is longer (mesio-distally) than wide (bucco-lingually) in early wear stages; with further wear this ratio changes to wider than long (compare Figs. 3Q View Fig –AD, 4G–M, N 1).
The hypostria ends well above the crown base and is the longest stria (Fig. 4K 3, N 3). Buccal striae are only present in early wear stages and thus very short, terminating within the first third of the tooth crown (Fig. 4K 2, N 2). The parastria and metastria are very short and nearly non-existent in one very slightly worn M1/2 (GPIT/MA/13820; Figs. 3R View Fig , 4H). The similarly slightly worn M1/2SNSB-BSPG 2020 XCIV-5366 exhibits no parastria (and thus a primary parafossette) but a well-expressed (4 mm long) metastria ( Figs. 3Q View Fig , 4G). The mesostria is the longest buccal stria, only present in M1/2of earlier wear stages (GPIT/MA/13820, 16134, 16845, SNSB-BSPG 2020 XCIV-1391, 1724, 5366, 5367, 5368, 5370, 5371, 5372 and 5377; Figs. 3Q View Fig –AA, 4G–M). In four of these (GPIT/MA/16134, 16845, SNSB-BSPG 2020 XCIV-1724 and 5366) an additional, but very short metastria is also exposed ( Figs. 3Q, V–X View Fig , 4G, K).
Form and orientation of flexus and fossettes on the occlusal surface are quite similar to P4 but the parafossette is much smaller or missing in heavily worn M1/2( GPIT / MA/10731, 17163) while the hypoflexus is elongated. In two cases of M1/2, meso- and metaflexus/fossette are interconnected at mid length ( GPIT /MA/13820 and SNSB-BSPG 2020 XCIV-1391 ; Figs. 3R, U View Fig , 4H, I); in one separate case they are fused at the terminal end of the metaflexus ( GPIT /MA/16134; Fig. 3V View Fig ). In the least worn M1/2 ( GPIT / MA/13820 and SNSB-BSPG 2020 XCIV 5366 ), the para- and metafossette are of irregular outline ( Figs. 3Q, R View Fig , 4G, H). Three slightly worn M1/2 show an additional tiny enamel column/stylid at the base of the mesostria ( GPIT /MA/13820, SNSB-BSPG 2020 XCIV-5377 and 5368; Figs. 3R, Z View Fig , 4H, M). All M 1/2 have three roots: one dominant lingual root and two small buccal roots (Fig. 4K 2, N 2) .
M3: The M 3 is the shortest tooth of the toothrow (Fig. 4Q 2, P 2). The occlusal outline of the M3 is square but slightly elongated distally. The hypostria ends well above the crown base and is the longest stria like in the other upper molars. Only in two specimens, representing unworn, unrooted and thus not fully developed M3, the hypostria ends very slightly above the crown base ( SNSB-BSPG XCIV-1320 and 3388; Fig. 4O 2, P 2). Buccal striae are short and terminate within the first third of the height of the tooth crown. The mesostria is the longest buccal stria, usually followed by the parastria .
The metastria is very short and only present in four lesser worn M3 where it is located at the distobuccal corner in three specimens ( GPIT /MA/10990, 12562 and SNSB-BSPG 2020 XCIV-0446 ; Figs. 3 View Fig AH, AI, AL, 4 R) and slightly shifted to the posterior side in SNSB-BSPG 2020 XCIV-0415 ( Figs. 3 View Fig AG, 4Q) .
The two unworn M3 show a para- and a mesoflexus/-stria but no metastria (and thus a primary metafossette) ( SNSB-BSPG 2020 XCIV-1320 ; Figs. 3 View Fig AF, 4P 1, P 2) or a very short
→ Fig. 4. Upper (A–T) and lower (U–AM) cheek teeth of the beaver Steneofiber depereti Mayet, 1908 , from the early Later Miocene locality Hammerschmiede (Bavaria, Germany), local stratigraphic levels HAM 5 and HAM 4. Deciduous premolars: (A, B, U–V); premolars (C–F, W–AA); molars (G–N, O–T, AB–AI, AJ–AN). Occlusal (A, B 1, C, D 1 –F 1, G–J, K 1, L, M, N 1 –P 1, Q–U, V 1– X 1, Y,Z 1, AA 1, AB, AC 1 –AF 1, AI–AH, AJ 1, AK,AL,AM 1, AN), lingual (B 2, D 2 –F 2, K 3, N 3 –P 3, W 3, X 3, AC 2, AD 3, AE 2, AF 2, AJ 3, AM 2), and buccal (B 3, D 3, K 2, N 2, O 3, P 2, V 2 –X 2, Z 2, AA 2, AC 3, AD 2, AJ 2, AM 3) views. Left DP4: (A) GPIT/MA/10744, HAM 5. Right DP4: (B) GPIT/MA/17763, HAM 4. Left P4: (C) SNSB-BSPG 2020 XCIV-3891, HAM 4; (D) GPIT/MA/10989, HAM 4; (F) GPIT/MA/10746, HAM 5. Right P4: (E) GPIT/MA/16935, HAM 4. Left M1/2: (G) SNSB-BSPG 2020 XCIV-5366, HAM 4; (H) GPIT/MA/13820, HAM 5. Right M1/2: (I) SNSB-BSPG 2020 XCIV-1391, HAM 4; (J) SNSB-BSPG 2020 XCIV-5372, HAM 4; (K) GPIT/MA/16845, HAM 4; (L) SNSB-BSPG 2020 XCIV-5370, HAM 4; (M) SNSB-BSPG 2020 XCIV-5368, HAM 4; (N) SNSB-BSPG 2020 XCIV-1726, HAM 4. Right M3: (O) SNSB-BSPG 2020 XCIV-3388, HAM 4. Left M3: (P) SNSB-BSPG 2020 XCIV-1320, HAM 4; (Q) SNSB-BSPG 2020 XCIV-0415, HAM 4; (R) GPIT/MA/12562, HAM 4; (S) GPIT/MA/16530, HAM 4; (T) SNSB-BSPG 2020 XCIV-1729, HAM 4. Right dp4: (U) GPIT/MA/13826, HAM 5; (V) GPIT/MA/10785, HAM 5. Right p4: (W) GPIT/MA/10745, HAM 4; (X) SNSB-BSPG 2020 XCIV-5362, HAM 4. Left p4 (Y) SNSB-BSPG 2020 XCIV-0487, HAM 4; (Z) SNSB-BSPG 2020 XCV-0303, HAM 5; (AA) GPIT/MA/09896, HAM 5. Right m1/2: (AB) GPIT/MA/16915, HAM 4; (AD) GPIT/MA/10987, HAM 4; (AE) GPIT/MA/16672, HAM 4; (AF) GPIT/MA/09906, HAM 5; (AI) GPIT/MA/12260, HAM 5. Left m1/2: (AC) SNSB-BSPG 2020 XCIV-5364, HAM 4; (AG) GPIT/MA/12342, HAM 5; (AH) GPIT/MA/13824, HAM 5. Right m3: (AJ) SNSB-BSPG 2020 XCIV-1722, HAM 4; (AK) GPIT/MA/13823, HAM 5; (AN) GPIT/MA/09907, HAM 5. Left m3: (AL) GPIT/MA/17388, HAM 4; (AM) SNSB-BSPG 2020 XCIV-1719, HAM 4.
para-, a dominant meso- and a nearly as dominant metaflexus/-stria ( SNSB-BSPG 2020 XCIV-3388 ; Figs. 3 View Fig AE, 4O 1, O 3). The former M3 shows a well-expressed paraflexus forming a “U”, crossing the tooth buccolingually and then turning back mesially to the buccal margin. The latter M3 exhibits additional enamel columns/stylids within the mesostria, the metastria and at the lingual hypostria (Fig. 4O) .
In more advanced wear stages, the paraflexus/fossette is randomly separated into a large mesial and a small distal fossette ( GPIT /MA/10748, 10990, 12562 and SNSB-BSPG 2020 XCIV-0415 ; Figs. 3 View Fig AG– AI, AK, 4Q, R). The slightly worn GPIT /MA/12562 shows an additional third paraflexus/-stria that is small but open buccally ( Figs. 3 View Fig AH, 4 R) . The most heavily worn M3 show in two cases only one hypo-, para-, meso-, and metafossette ( GPIT /MA/16530 and SNSB-BSPG 2020 XCIV-1728 ; Figs. 3 View Fig AM, AN, 4S) and in one case only hypo-, meso-, and a tiny metafossette ( SNSB-BSPG 2020 XCIV-1729 ; Figs. 3 View Fig AO, 4 T) .
All M3 have three roots, like the M1/2, with one dominant lingual root and two small buccal roots. Only the two unworn M3 (SNSB-BSPG 2020 XCIV-1320 and 3388) are still rootless and open at the base (Fig. 4O 3, P 2).
Lower dentition: The material consists of 12 i2 (seven isolated tips, two fragments in situ, three complete teeth in situ), six dp4 (two still in their mandible), 18 p4 (four preserved in their mandible), 44 m 1/2 and 14 m 3, of which 18 molars are still in situ in ten jaw fragments (nine m1, seven m2 and two m3).
i2: Seven of the 12 lower incisor specimens include a preserved tip. In contrast to the upper incisor, the wear facet of the lower i2s is constantly angled and smooth. The wear facet is longer than in the upper I2 and extends from the labial enamel tip to the lingual edge. In cross section the lower incisors show a lingually elongated triangle. The lingual tip of the triangle is rounded and situated mesially. The mesial surface is nearly flat and parallel with the symphysis of the mandibles. The enamel face is convex in juvenile specimens (GPIT/MA/16436, 16985, and 17569), but it is “semiflattened” in older individuals, with a flattened mesial and a convex distal half of the enamel face.
dp4: All six dp4 are worn and para- and metafossetids are visible ( Fig. 5A, B, F–H View Fig ). Three of the dp4 are strongly worn and a closed mesoflexid is visible ( GPIT /MA/13826, 10785, SNSB-BSPG 2020 XCIV-5365 ; Figs. 4U, V 1 , 5 G–I,). In the medium worn specimens, the mesoflexid is open and associated with a short mesostriid ( Fig. 5A, B, F View Fig ). All dp4 show a well-expressed hypoflexid with an associated hypostriid that terminates shortly above the crown base but extends as a groove until the tooth base (Fig. 4 V 2 ). The mesostriid is clearly longer than the meta- and parastriid (if present), but the hypostriid is always the longest. Synclines of the dp4 are never filled with cement. In all dp4 with preserved roots, two dominant main roots diverge mesially and distally, and a tiny third root protrudes buccally, mesially to the hypostriid ( GPIT /MA/10785, 16950, and 17569; Fig. 4 V 2 ). GPIT /MA/17569 shows two additional small and circular fossettids: one mesiobuccal (preparafossettid) and another distolingual (premesofossettid) ( Fig. 5A View Fig ) .
p4: In premolars that are only slightly or medium worn, the typical eight-shaped occlusal outline is visible (Figs. 4W 1, X 1, 5J–L). With increasing wear, the anterior part of the worn surface of the p4 extends in length mesially, whereas its width remains unchanged. With the last wear phase, an antero-lingual edge is forming that extends the mesiolingual part of the p4 up to the level of its distal part (Figs. 4Y, AA 1, 5C, D, N–P). The hypostriid always ends very close (approximately 3 mm) to the base of the crown. Slightly below the closure of the hypostriid, a well-expressed groove extends to the base of the tooth (Fig 4W 2, X 2, Z 2, AA 2). The closure of the hypostriid can easily be overlooked in teeth of higher wear stages due to the increased accumulation of cementum in the striids; therefore, the continuing groove can be misinterpreted as an open hypostriid that reaches the tooth base.
Only in slightly worn p4 ( GPIT /MA/10727, 10745), para- and metastriids of equal length are exposed and are closing within the first quarter of the tooth length (Figs. 4W 1, W 3, 5J, K). In all specimens with more advanced wear stages the para- and metaflexid/striid are closed and their para- and metafossettid are visible. Generally, lower premolars show a well-developed mesostriid/flexid extending at least halfway down to the tooth base (Fig. 4W 3, X 3). Only in the most heavily worn p4 ( GPIT /MA/09896, SNSB-BSPG 2020 XCV-0303, 0487) the mesostriid/flexid is just closed and the mesofossettid is present (Figs. 4Y, Z 1, AA 1, 5N –P). In slightly worn p4 the hypoflexid is straight and diagonally oriented in medio-distal direction. The hypoflexid crosses approximately one third of tooth width and ends between the meso- and metaflexid. Only in the least worn premolars ( GPIT / MA/10727, 10745 and SNSB-BSPG 2020 XCIV-5362 ), the hypoflexid ends in line with the ends of the meso- and metaflexid (Figs. 4W 1, X 1, 5J–L). In GPIT /MA/10727 the meso- and metaflexid are fused with the hypoflexid ( Fig. 5K View Fig ). In moderate to heavy wear stages, the hypoflexid of lower premolars is hook-shaped and oriented more distally, never crossing the midline of tooth width. In these advanced wear stages, the mesoflexid/fossettid are more elongated, run mesially side by side with the terminating hypoflexid by forming a mesiobuccally oriented hook ( GPIT /MA/09896, 13980, 16839 and SNSB-BSPG 2020 XCIV-0487 ; Figs. 4Y, AA 1, 5E, M, N, P), or stay straight ( SNSB-BSPG 2020 XCV-0303; Figs. 4Z 1, 5O). The mesoflexid is the shortest of the lingual flexids/fossettids and it slightly crosses the midline of the tooth width. The para- and metaflexids/fossettids run two thirds along the tooth width before they terminate. The shape of the paraflexid/fossettid on the occlusal surface is variable, showing a straight course or a convex ( GPIT /MA/16839; Fig. 5E View Fig ) to concave ( GPIT /MA/09909; Fig. 5C View Fig ) hook-shaped orientation. The metaflexids/fossettids are slightly undulating. In SNSB-BSPG 2020 XCIV-0487 all lingual fossetids are heavily undulating (Figs. 4Y, 5P) GoogleMaps .
m1/2/3: The typical outline of the lower molars is rectangular. The hypostriid/flexid is the longest striid/flexid and ends shortly above the crown base and closes to a hypofossetid without any lingual groove in contrast to the p4. The mesostriid is always longer than the para- and metastriid, both of which having the same length. Para- and metastriid are only present in the first millimetres of wear and they close within the first fourth of the tooth crown length. In contrast the mesostriid continues downwards until it closes before reaching half of the tooth crown height in m1/2 (Fig. 4 AC 2 , AD 3, AE 2, AF 2,), but surpasses the half length of the crown height in m3 (Fig. 4 AJ 3 , AM 2 ) . The latter is bucco-lingually slightly narrower and approximately 20% shorter in crown height than a typical m1/2 (compare Fig. 4 AC 2 , AC 3 , AJ 2 , AJ 3 , AM 2 , AM 3 ) . In unworn and slightly worn molars, some special features in lingual flexids/fossettids are obvious: unworn molars show a U-shaped paraflexid that is oriented transversally on the occlusal surface, nearly reaching the buccal margin until it is reversing mesially all way back near the lingual tooth margin (Figs. 4 AB, AC 1 , AJ 1 , 5 B, Q, U, AC). In slightly worn m1/2 this “U” is divided and yields a typical straight transversal paraflexid and one elongated preparafossettid (Figs. 4 AE 1 , 5 B, R). With continuing wear this preparafossettid splits in two preparafossettids, a lingual and a buccal preparafossettid ( GPIT /MA/09906, 10728, 10987, and 17569 [m1]; Figs. 4AF 1, AD 1, 5A, S, T, V). In a single case a third preparafossettid appears ( GPIT /MA/17569 [m2]; Figs. 5A View Fig , 6C View Fig 2 View Fig ). Another singular specimen shows a Y-shaped paraflexid where the two endings encompass the buccal preparafossetid. Furthermore, the same m1/2 shows a second, lingual preparafossetid that is barely visible and nearly worn out ( GPIT /MA/10987; Figs. 4AD, 5 V). All preparafossettids are removed due to tooth wear before any lingual flexid closes. The medium worn GPIT /MA/17388 (m3) and the heavily worn SNSB-BSPG 2020 XCIV-5360 (m1/2) exhibit an interrupted parafossetid that is split into a lingual and a buccal parafossetid of equal dimensions (Figs. 4AL, 5Y, AG) . In the most heavily worn molar only a hypo- and mesofossette is present ( GPIT /MA/12260) (Figs. 4 AI, 5 AB). Three molars show tiny additional enamel columns or stylids at the lower ends of some lingual striids ( GPIT /MA/16672, m1/2: parastriid and mesostriid; Figs. 4AE 1, AE 2, 5 R; GPIT /MA/09906, m1/2: parastriid and mesostriid, Figs. 4AF 1, AF 2, 5S; GPIT / MA/13823, m3: only one stylid at the paraflexid, Figs. 4AK, 5AD). In general, paraflexid/fossettid, mesoflexid/fossettid and metaflexid/fossettid are straight or slightly undulating and transversely oriented on the occlusal surface .
Mandibles: The description of the mandible is mainly based on the four better preserved specimens: a nearly complete right mandible comprising of the angular process, part of the coronoid process, i2 and m1 (GPIT/MA/13813, Fig. 6A View Fig ); a well-preserved right mandible with articular process, p4, m1, and m3 (GPIT/MA/09909, Fig. 6B View Fig ); a mandible fragment with i2 (fragment) and p4–m2 (GPIT/MA/17068, Fig. 6D View Fig ); and a juvenile left mandible with i2 and dp4–m2 (GPIT/MA/17569, Fig. 6C View Fig ). In addition to that, the mandibular material consists of two isolated articular processes (GPIT/MA/16586, 17215) and eight smaller mandibular fragments (GPIT/MA/10742, 16767, 16839, 16950, 17280, 18106, SNSB-BSPG 2020 XCIV-1494 and 2134).
In lateral view, the chin process is pointed postero-ventrally; it is situated anterior to the p 4 in the older individuals (GPIT/MA/09909, 13813, and 17068; Fig. 6A View Fig 2 View Fig , B 4, D 1) and at the same height as the dp 4 in the juvenile specimen GPIT/MA/17569; Fig. 6C View Fig 1 View Fig ). The mental foramen is situated anterior to the p4 (GPIT/MA/09909, 17068) and at the same height as the anterior margin of dp4 (GPIT/MA/17569). The m3 and parts of the m2 are hidden by the anterior margin of the coronoid process (GPIT/MA/09909, 17068, 17569) and a deep masseteric fossa is situated dorsal to the posterior end of the incisor (GPIT/MA/09909, 13813).
In lingual view, the angular shelf (crista pterygoidea) starts posterior to the m3; it bends horizontally and is expanded at the ventral margin (GPIT/MA/09909, 13813), thus a clear and distinct fossa for the pterygoid muscle is visible ( Fig. 6A View Fig 1 View Fig , B 2 View Fig ). GPIT/MA/13813 has an elongated mandibular foramen that is situated posteriorly to the m3 at a crest starting at the lingual alveolar rim and continuing to the condylar process ( Fig. 6A View Fig 1 View Fig , A 4). In the juvenile specimen (GPIT/MA/17569) this foramen is situated labially to this crest, directly posterior to the m3 alveolus ( Fig. 6C View Fig 2 View Fig , C 3 View Fig ). The symphysis is pointed to the chin process and expands dorsally. The occlusal margin of the toothrow is concave and slightly inclined posteriorly.
In posterior view, the coronoid and the angular processes are arranged in a vertical line ( Fig. 6A View Fig 3 View Fig ). The articular process is shifted lingually to this line (GPIT/MA/09909, 13813; Fig. 6A View Fig 3, B 3 View Fig ).
| GPIT |
Institut und Museum fur Geologie und Palaeontologie, Universitat Tuebingen |
| R |
Departamento de Geologia, Universidad de Chile |
| AM |
Australian Museum |
| T |
Tavera, Department of Geology and Geophysics |
| AC |
Amherst College, Beneski Museum of Natural History |
| V |
Royal British Columbia Museum - Herbarium |
No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.
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