Figure 1.
Dental orientation and terminology of Arboroharamiya.
A. Cusp numbering in a right upper molar. B. Cusp numbering in a right lower molar. The terminology follows Butler [19].
Figure 2.
Mandibles of Arboroharamiya jenkinsi.
A, Buccal view of the right mandible with p4 and the incisor (i). B, Lingual view of the left mandible with p4-m1 and the incisor. C, Close-up view of the angular process area of B, showing no groove or attachment site for the Meckel’s cartilage or the postdentary bones. Scale bar in A is 5 mm. Red arrow points to the possible coronoid bone. A and B are modified from Zheng et al. [26] A new arboreal haramiyid shows the diversity of crown mammals in the Jurassic period. Nature 500: 199–202 (DOI: 10.1038/nature12353). Reproduced by permission of Nature Publishing Group. Abbreviations: ap, angular process; am2, alveolus for m2; amf, anterior extremity of the masseteric fossa; cp, coronoid process; mc, mandibular condyle; mf, mandibular foramen.
Figure 3.
Lower premolar (p4) of Arboroharamiya jenkinsi.
A, Lingual view of p4. B, Buccal view of p4. Abbreviations: 1–4, cusps 1–4 on the heel of p4, ranging from the lingual to the buccal side of the tooth; brd, buccal ridge on the main cusp of p4; lrd, lingual ridge on the main cusp of p4. Note the lack of serrations on both sides of the tooth crown.
Figure 4.
Lower m1s of Arboroharamiya jenkinsi (STM33-9).
A–A1, Occlusal view of the right m1. B–B1, Lingual view of the right m1. C–C1, Buccal view of the right m1. D, Lingual view of the left m1. E, Occlusal view of the left m1 (slightly tilted). F, Close-up view showing the wear facets on the lingual side of the lingual (row a) cusps. A1–B1 are SEM photographs. All images are on the same scale except for F.
Figure 5.
Right m2 of Arboroharamiya jenkinsi (STM33-9).
A–A1, Occlusal view; B–B1, Lingual view. C–C1, Buccal view. Note the breakage at b1. Note cusp a3 and a4 are slightly displaced in A–C, but restored to their anatomical positions in A1–C1. A1–C1 are SEM photographs. All images are on the same scale.
Figure 6.
Left upper incisor of Arboroharamiya jenkinsi (STM33-9).
A–A1, Occlusal view; B–B1, Mesial view. C–C1, Distal view. A1–C1 are SEM photographs. All images are on the same scale.
Figure 7.
Left P3 of Arboroharamiya jenkinsi (STM33-9).
A–A1, Occlusal view; B–B1, Lingual view. C–C1, Buccal view. A1–C1 are SEM photographs. All images are on the same scale.
Figure 8.
P4s of Arboroharamiya jenkinsi (STM33-9).
A–A1, Occlusal view of the left P4; B, Mesial view of the left P4; B1, Mesiobuccal view of the left P4; C, Distal view of the left P4; C1, Lingual view of the left P4. D–D1, Occlusal view of the right P4; E, Mesial view of the right P4. E1, Lingual view of the right P4. F, Distal view of the right P4. F1. Buccal view of the right P4. A1–F1 are SEM photographs. All images are on the same scale.
Figure 9.
Right M1 of Arboroharamiya jenkinsi (STM33-9).
A–A1, Occlusal view. B–B1, Lingual view. C–C1, Buccal view. A1–C1 are SEM photographs. All images are on the same scale.
Figure 10.
Partial M2s of Arboroharamiya jenkinsi (STM33-9).
A, Occlusal (tilted) views of the buccal part of left M2 with cusps A2–A5 and lingual side of right M2 with cusps B1–B6 preserved in slab a. B, Impressions of cusps in A preserved in the counterpart of the slab. The buccal half of the right M2 is still in the matrix of the counterpart. A5’, B1’ and B3’ are impressions of the corresponding cusps in A. Images are on the same scale.
Figure 11.
Occlusal and wear pattern of Arboroharamiya jenkinsi (STM33-9).
A–D, Distal, lingual, mesial and buccal views of the right M1 and m1 in occlusion. E, Occlusal view (SEM photograph) of the right m1 with wear facets outlined with red lines. F, Occlusal view (SEM photograph) of the right M1 with the wear facets outlined with red lines. G, Diagram showing the tooth cusp relationships of M1 and m1 in occlusion. H, Diagram showing the tooth cusp relationship of M1 and m1 when m1 moves distally at the end the palinal cycle of the chewing motion. A–D and G–H are modified from Zheng et al. [26]. A new arboreal haramiyid shows the diversity of crown mammals in the Jurassic period. Nature 500: 199–202 (DOI: 10.1038/nature12353). Reproduced by permission of Nature Publishing Group. Images are not on the same scale.
Figure 12.
SEM photographs showing tooth microwear of Arboroharamiya jenkinsi (STM33-9).
A, Crown view of the upper left incisor. The bed boxes G and F correspond to the close-up images in G and F. B, Crown view of the right m2, with the red box H corresponding to the close-up image H. C, Lingual view of the right m1 with the red box I corresponding to the close-up view in I. D, Crown view of the right P4 with the red box J corresponding to the close-up view J. E, Crown view of the right M1 with the red box K corresponding to the close-up view in K. Blue arrows in J indicate worn cusps in the tooth basin of P4. Blue arrows in F-I and K indicate the directions of striations on the wear facets. Images are not on the same scale.
Figure 13.
Tooth comparison between Arboroharamiya jenkinsi and other haramiyidans and Megaconus.
A, Left P3 of Arboroharamiya. B, “Upper molariform tooth” of Sineleutherus issedonicus (PIN no. 5087/16) [15], which we think is most likely a right P3. C, Right M1 of Arboroharamiya. D, “Right upper molar” of Eleutherodon oxfordensis (M46832) [13], which we think is a left upper molar. E, Right m2 of Arboroharamiya. F, “Right lower molariform tooth” of Sineleutherus issedonicus (PIN, no. 5087/9) [15], which we think is a left lower m1 or m2. G, “Left lower molariform tooth” of Sineleutherus uyguricus (SGP 2001/33) [14], [31], which we think is a right m1 or m2. H, Left m3 of Megaconus (PMOL-AM00007) [28]. I, Upper dentition of Megaconus (PMOL-AM00007) [28]. The red arrow points to the mesial end of the upper molar. The blue arrow points to the distal end of the lower molar. The yellow points to the wear facets on the buccal (w1) and lingual (w2) wear facets of A1 (our interpretation). The cusp designation between brackets is our interpretation. Tooth images other than those of Arboroharamiya are from references cited. Images are not on the same scale.
Figure 14.
Orientations of the dentition in Megaconus.
The hypothetic skull outline shows the palatal region where the occlusal views of the upper teeth are illustrated. In scenario A, which is the interpretation of Zhou et al. [28], the longer cusp row in M3 (row B) and the shortest cusp row in M2 are on the lingual side. Relative to the last molar, M1 and M2 shift lingually. In scenario B, which is our interpretation, the longer cusp row in M3 (row A) and the shortest cusp row in M2 are buccal. In relation to M1 and M2, M3 shifts lingually. The tooth images are from Zhou et al. [28]. A Jurassic mammaliaform and the earliest mammalian evolutionary adaptations. Nature 500: 163–167 (DOI: 10.1038/nature12429). Reproduced by permission of Nature Publishing Group.