Computed tomographic analysis of the dental system of three Jurassic ceratopsians and implications for the evolution of tooth replacement pattern and diet in early-diverging ceratopsians
- School of Earth Sciences, China University of Geosciences, China
- Department of Biological Sciences, The George Washington University, United States
- Centre for Vertebrate Evolutionary Biology, Yunnan University, China
- Key Laboratory of Vertebrate Evolution and Human Origins, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, China
- Center for Excellence in Life and Paleoenvironment, Chinese Academy of Sciences, China
- Nanjing Museum of Paleontology, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, China
Figures
Figure 1
3D reconstructions of maxillary teeth in Yinlong downsi (IVPP V18638).
Transparent reconstructions of the right maxilla in labial (A) and lingual (B) views, and right maxillary dentitions in labial (C) and lingual (D) views. The reconstructions of maxillary dentitions are transparent in D. Elements in the CT reconstructions are color coded as follows: functional maxillary teeth, yellow; replacement teeth, cyan. Abbreviations: M1–M13, the 1st to 13th functional teeth in the maxilla; rM1, rM2, and rM10, the replacement teeth in the 1st, 2nd, and 10th tooth alveolus; pc, pulp cavity. Scale bars equal 5 cm (A, B) and 2 cm (C, D).
Figure 2
3D reconstructions of premaxillary and cheek teeth in Yinlong downsi (IVPP V18636).
Transparent reconstruction of the skull in right (A) and left (B) lateral views. The right tooth rows in labial (C) and lingual (E) views. The left tooth rows in labial (D) and lingual (F) views. The premaxillary teeth in rostral (G) view. Maxillary and dentary dentitions in rostral (H) view. Elements in the CT reconstructions are color coded as follows: functional premaxillary teeth, green; functional maxillary teeth, yellow; functional dentary teeth, lavender; replacement teeth, cyan. Abbreviations: M1–M11, the 1st to 11th functional teeth in the maxilla; rM3 and rM10, the replacement teeth in the 3rd and 10th alveolus; D2–D12, the 2nd to 12th functional teeth in the dentary; PM1 and PM2, the 1st and 2nd premaxillary functional teeth; wf, wear surface. Scale bars equal 5 cm (A, B), 3 cm (C–F), and 2 cm (G, H).
Figure 3
3D reconstructions of premaxillary and cheek teeth in Yinlong downsi (IVPP V14530).
Transparent reconstructions of the skull in right (A) and left (B) lateral views. The premaxillary and maxillary dentitions in labiodorsal (C) view. The dentary dentitions in labiodorsal (D) view. Tooth rows in the upper (E) and lower (F) jaws in dorsal view. The premaxillary teeth in rostral (G) view. The right tooth row in the upper jaw in labial (H) view. Elements in the CT reconstructions are color coded as Figure 2. Abbreviations: M1–M13, the 1st to 13th functional teeth in the maxilla; rM9, the replacement tooth in the 9th alveolus; D1–D15, the 1st to 15th functional teeth in the dentary; PM1–PM3, the 1st to 3rd functional teeth in the premaxilla; rD8 and rD13, the replacement teeth in the 8th and 13th alveolus. Scale bars equal 5 cm (A, B) and 4 cm (C–H).
Figure 4
3D reconstructions of premaxillary and maxillary teeth in the largest specimen (IVPP V18637) of Yinlong downsi.
Transparent reconstructions of the skull in right (A), occlusal (B), and left (C) views. Right tooth row in labial (D) and lingual (F) views. Left tooth row in labial (E) and lingual (G) views. Elements in the CT reconstructions are color coded as Figure 2 and remnants of functional teeth are coded as red. Abbreviations: OF, remnants of the old functional tooth; M1–M14, the 1st to 14th functional teeth in the maxilla; PM1–PM3, the 1st to 3rd functional teeth in the premaxilla; rM7, the replacement tooth in the 7th alveolus. Scale bars equal 10 cm (A–C) and 4 cm (D–G).
Figure 5
3D reconstructions of premaxillary and cheek teeth in Chaoyangsaurus youngi (IGCAGS V371).
Transparent reconstructions of the skull in occlusal (A) and right lateral (C) views. Transparent reconstructions of the mandible in occlusal (B) and right lateral (D) views. Left maxillary and premaxillary dentitions in lingual (E) and labial (F) views. Right premaxillary and maxillary dentitions in lingual (G) and labial (H) view. Dentary dentitions in right dorsal (I) and left dorsal (J) views. The reconstructions of maxillary dentitions are transparent in F and H. Elements in the CT reconstructions are color coded as Figure 2. Abbreviations: M1–M9, the 1st to 9th functional teeth in the maxilla; D1–D11, the 1st to 11th functional teeth in the dentary; PM1–PM2, the 1st to 2nd functional teeth in the premaxilla. Scale bars equal 3 cm (A–D) and 2 cm (E–J).
Figure 6
Hualianceratops wucaiwanensis, IVPP V28614.
The left dentary in labial (A) and lingual (B) views. Dentary tooth row in labial (C) and lingual (D) views. Abbreviations: r, rostral; RT, replacement tooth. Scale bars equal 2 cm (A, B) and 1 cm (C, D).
Figure 7
Three different replacement processes illustrated by teeth at similar replacement stage of Chaoyangsaurus (A, D), Yinlong (B, E), and Liaoceratops (C, F).
The tooth 8 in the left maxilla of IGCAGS V371 in distal view (A) and cross-section (D). The tooth 10 of IVPP V18638 in mesial view (B) and cross-section (E). The tooth 7 in the right maxilla of the holotype of Liaoceratops (IVPP V12738) in mesial view (C) and cross-section (F). Elements in the CT reconstructions are color coded as Figure 2. The arrows of A–C indicate where the cross-sections generate. The replacement teeth here have developed the complete crown and part of the root. The root of the replacement tooth in Liaoceratops inclines lingually and that in Yinlong also inclines lingually but with a smaller angle of inclination. The root of the replacement tooth in Chaoyangsaurus clings to its corresponding functional tooth tightly. The resorbed area on the functional tooth is larger in Chaoyangsaurus and Yinlong than in Liaoceratops because of the larger contact area. Therefore, the resorption degree of the functional tooth in Chaoyangsaurus and Yinlong is also larger than in Liaoceratops. Scale bars equal 5 mm (A–C) and 3 mm (D–F).
Figure 8
Z-Spacing diagrams of Yinlong downsi (IVPP V14530 and IVPP V18638) and Chaoyangsaurus youngi (IGCAGS V371).
Zahnreihen graphs of right maxillary dentitions of IVPP V14530 (A) and right maxillary dentitions of IVPP V18638 (B). Zahnreihen graphs of IGCAGS V371 in the left maxilla (C), right maxilla (D), left dentary (E), and right dentary (F). The x-axis is the tooth position, y-axis is the tooth replacement stage. The black triangle represents the functional tooth and the gray circle represents the replacement tooth. Each imaginary line represents the Z-spacing which is the distance between Zahnreihen whose unit is a tooth position.
Figure 9
The reconstructions of three functional maxillary teeth at the middle part of the tooth row.
The tooth 6 in IVPP V18638 in mesial, labial view (A), and cross-section (D). The tooth 7 in the left maxilla of IGCAGS V371 in mesial, labial view (B), and cross-section (E). The tooth 9 in the left maxilla of the holotype of Liaoceratops in distal, labial view (C), and cross-section (F). The arrows indicate where the cross-sections generate. Scale bar equals 10 mm (A–C) and 5 mm (D–F).
Figure 10
Phylogenetic tree of ceratopsians (composite from Erickson et al., 2015, Han et al., 2018, and Yu et al., 2020) and comparison of the dental anatomy and the tooth replacement pattern.
Psittacosaurus from Averianov et al., 2006; Liaoceratops from He et al., 2018; Auroraceratops from Tanoue et al., 2012 and Morschhauser et al., 2019; Leptoceratops from Tanoue et al., 2012; Protoceratops from Edmund, 1960 and Brown and Schlaikjer, 1940; Triceratops from Edmund, 1960.
Tables
Table 1
List of the ontogenetic difference in specimens of Yinlong.
| Specimen number | Alveoli | The replacement teeth | Resorbed functional teeth | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Premaxilla | Maxilla | Dentary | Premaxilla | Maxilla | Dentary | ||||||||
| Left | Right | Left | Right | Left | Right | Left | Right | Left | Right | Left | Right | ||
| IVPP V18638 | n.p. | n.p. | n.p. | 13 | n.p. | n.p. | n.p. | n.p. | n.p. | 3 | n.p. | n.p. | 0 |
| IVPP V18636 | 2 | 1 | 12* | 10* | 9* | 12* | 0 | 0 | 0 | 2 | 0 | 0 | 0 |
| IVPP V14530 | 3 | 3 | 13 | 13 | 15 | 14 | 0 | 0 | 1 | 1 | 1 | 1 | 0 |
| IVPP V18637 | 3 | 3 | 14 | 14 | n.p. | n.p. | 2 | 0 | 0 | 1 | n.p. | n.p. | Right maxilla: 2 |
-
n.p. = not preserved.
-
*
represents the loss of alveoli.
Table 2
List of the number of replacement teeth and the functional teeth in some ceratopsians which have been studied by computed tomography.
| Higher taxa | Genus | Specimen number | Left maxilla | Right maxilla | Left dentary | Right dentary | ||||
|---|---|---|---|---|---|---|---|---|---|---|
| Ceratopsia | Psittacosaurus | CUGW VH104 | 9 FT | 7 RT | 9 FT | 5 RT | 9 FT | 6 RT | 10 FT | 7 RT |
| Ceratopsia | Yinlong | IVPP V14530 | 13 FT | 1 RT | 13 FT | 1 RT | 14 FT | 1 RT | 14 FT | 2 RT |
| Ceratopsia | Chaoyangsaurus | IGCAGS V371 | 9 FT | 3 RT | 9 FT | 3 RT | 9 FT | 3 RT | 11 FT | 5 RT |
| Neoceratopsia | Liaoceratops | IVPP V12738 | 13 FT | 11 RT and 1 2nd RT | 13 FT | 11 RT and 1 2nd RT | 15 FT | 13 RT and 2 2nd RT | 15 FT | 12 RT |
| Neoceratopsia | Auroraceratops | CUGW VH106 | - | - | - | - | - | - | 15 FT | 7 RT |
-
RT = replacement tooth; FT = functional tooth; 2nd RT = the second generation replacement tooth.
Table 3
Skull length and scanning parameters of Yinlong and Chaoyangsaurus.
| Taxa | Specimen number | Skull length*(cm) | Scanning voltage | Scanning current | Resolution (µm) |
|---|---|---|---|---|---|
| Yinlong | IVPP V18638 | 13.4 (uncomplete) | 130 kV | 140 mA | 36.039 |
| Yinlong | IVPP V18636 | 15.5 | 430 kV | 1500 µA | 160 |
| Yinlong | IVPP V14530 | 18 | 430 kV | 1500 µA | 300 |
| Yinlong | IVPP V18637 | 23 | 430 kV | 1500 µA | 160 |
| Chaoyangsaurus | IGVAGS V371 | 13.7 | 150 kV | 160 mA | 46.493 |
-
*
Skull length is measured from the rostral end to the posterior surface of the quadrate condyles.
Additional files
-
Supplementary file 1
List of each functional and replacement tooth’s total height, maximum mesiodistal width, maximum labiolingual width, and the height of tooth remnants of all specimens.
- https://cdn.elifesciences.org/articles/76676/elife-76676-supp1-v2.xlsx
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Transparent reporting form
- https://cdn.elifesciences.org/articles/76676/elife-76676-transrepform1-v2.docx
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Computed tomographic analysis of the dental system of three Jurassic ceratopsians and implications for the evolution of tooth replacement pattern and diet in early-diverging ceratopsians
eLife 11:e76676.
https://doi.org/10.7554/eLife.76676
