Preservation of three-dimensional anatomy in phosphatized fossil arthropods enriches evolutionary inference
- University of Bonn, Germany
- Karlsruhe Institute of Technology, Germany
- Clemson University, United States
- State Museum of Natural History Stuttgart, Germany
Figures
Figure 1
Comparison between the fossil Onthophilus intermedius (A, D, G) and EtOH-fixed (B, E, H) and air-dried (C, F , I) specimens of O. striatus.
Slices of tomographic volumes showing head region (A–C), thorax (D–F) and abdomen (G–I). ae = aedeagus; ag = accessory gland; bpae = basal part of aedeagus; hg = hindgut; m = musculature; ml = median lobe; mr = muscles remnants; mscx = mesocoxa; msf = mesofemur; mst = mesotibia; mt = muscle tissue; mtcx = metacoxa; mtf = metafemur; mtt = metatibia; pcx = procoxa; sph = spherical particle; sm = stony matrix; t8 = 8th abdominal tergite; t9 = 9th abdominal tergite; t10 = 10th abdominal tergite; te = tentorium; tr = trachea.
Figure 2
Surface renderings of the eight Onthophilus intermedius specimens.
Note the unique encrustation of F1994.
Figure 3
Digital reconstruction of the fossil.
(A) Photograph of Onthophilus intermedius (F1994) ventrally embedded in a stony matrix. (B) Digital reconstruction showing fossilized beetle (green) and matrix (brown). (C) Beetle digitally isolated from the stone, revealing well-preserved morphology hidden by the matrix. (D) Perspective view of the fossil showing parts of exoskeleton, tracheal network, alimentary canal and genitals. (E, F) Comparison of the male genitals of the extant O. striatus (E) and the fossil O. intermedius (F); outer sclerites cut to reveal internal anatomy. See Supplementary file 1 for an interactive version of the 3D reconstruction.
Figure 4
Coxa-trochanteral joints.
Comparison of the joints (cut) of the left mid- (A, B) and hind leg (C, D) of Onthophilus striatus (A, C) and O. intermedius (B, D), showing coxae (green) and trochanters (yellow).
Figure 5
Digital endocast of Onthophilus intermedius (specimen F1994).
A digital endocast (A, B) artificially created from tomography data resembles the shape of the other fossils (Figure 2) much closer than the original surface of the beetle (C, D) hidden by the stony matrix.
Figure 6
Strict consensus tree.
The analysis places Onthophilus striatus within a lineage of Nearctic and far-eastern Palaearctic species (red), while O. intermedius is a member of a separate Holarctic lineage (blue). Four internal (purple) and three external (orange) unambiguous synapomorphies supporting their respective placements are mapped onto the cladogram - Onthophilus striatus group: Character 22:2, mesoventrite wide and short; 30:1, pygidial median carina absent; 35:2, tegmen of aedeagus abruptly downturned apically. O. intermedius group: 29:2, pygidium laterally impunctate; 36:2, tegmen of aedeagus abruptly narrowing apically; 40:2, lateral halves of eighth sternite large and nearly meeting at midline; 41:2, stem of spiculum gastrale broad throughout its length.
Appendix figure 1
Morphological characters visible in specimens other than F1994.
(A) Dorsal view of F1951, showing elytral carinae and foveae. (B) Posterolateral view of F1997, showing propygidial and pygidial carinae. (C) Posterior view of F1951. (D) Anterior view of F1995. (E) Valvifer and coxite of female ovipositor.
Tables
Table 1
Notes on the fossil Onthophilus intermedius specimens from Quercy and their preservation.
| ID | Internal structures preserved | Notes |
|---|---|---|
| F1951 | some sclerites (incl. coxa-trochanteral joints) and tracheae | the only specimen depicted by Handschin (1944); but not explicitly designated as holotype |
| F1992 | some sclerites and small tracheae | head, prothorax missing |
| F1993 | some sclerites (incl. coxa-trochanteral joints) | head, pygidia missing; elytra partly abraded |
| F1994 | most sclerites, muscle parts, tracheae, parts of alimentary system, large parts of male genitals | the only specimen of the collection that is ventrally encrusted by a stone matrix |
| F1995 | some sclerites, parts of male genitals | head present; abdomen deeply abraded dorsally |
| F1996 | some sclerites | head, prothorax missing |
| F1997 | some sclerites, remains of muscles below the elytra | head, prothorax partly abraded |
| F1998 | some sclerites (incl. coxa-trochanteral joints), parts of female genitalia | head, prothorax partly abraded |
Additional files
-
Supplementary file 1
Interactive 3D reconstruction of Onthophilus intermedius specimen F1994.
Click on the figure to start interactive 3D view; switch between views by using the menu (Adobe Reader 8.1 or higher required).
- https://doi.org/10.7554/eLife.12129.010
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Source code 1
Nexus code for character matrix.
- https://doi.org/10.7554/eLife.12129.011
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Preservation of three-dimensional anatomy in phosphatized fossil arthropods enriches evolutionary inference
eLife 5:e12129.
https://doi.org/10.7554/eLife.12129
