Biological asymmetry is present in all bilaterally symmetric organisms as a result of normal developmental instability. However, fossilized organisms, which have undergone distortion due to burial, may have additional asymmetry as a result of taphonomic processes. To investigate this issue, we evaluated the magnitude of shape variation resulting from taphonomy on vertebrate bone using a novel application of fluctuating asymmetry. We quantified the amount of total variance attributed to asymmetry in a taphonomically distorted fossil taxon and compared it to that of three extant taxa. The fossil taxon had an average of 27% higher asymmetry than the extant taxa. In spite of the high amount of taphonomic input, the major axes of shape variation were not greatly altered by removal of the asymmetric component of shape variation. This presents the possibility that either underlying biologic trends drive the principal directions of shape change irrespective of asymmetric taphonomic distortion, or that the symmetric taphonomic component is large enough that removing only the asymmetric component is inadequate to restore fossil shape. Our study is the first to present quantitative data on the relative magnitude of taphonomic shape change and presents a new method to further explore how taphonomic processes impact our interpretation of the fossil record.
Figure S1
Figure S1. Psittacosaurus lujiatunensis landmark figures showing landmarks (numbered) and semi-landmark curves (red) for the (A) scapula, (B) humerus in cranial view, (C) humerus in medial view, (D) humerus in caudal view, (E) ilium, (F) femur in cranial view, and (G) femur in caudal view. Scale = 25 mm.
FigS1-PsittacosaurLMFigFlat.tif
Figure S2
Figure S2. Red-tailed hawk (Buteo jamaicensis) landmark figures showing landmarks (numbered) and semi-landmark curves (red) for the (A) scapula, (B) humerus in cranial view, (C) humerus in medial view, (D) humerus in caudal view, (E) ilium, (F) femur in cranial view, and (G) femur in caudal view. Scale = 25 mm.
FigS2-RTHLMFigFlat.tif
Figure S3
Figure S3. American alligator (Alligator mississippiensis) landmark figures showing landmarks (numbered) and semi-landmark curves (red) for the (A) scapula, (B) humerus in cranial view, (C) humerus in medial view, (D) humerus in caudal view, (E) ilium, (F) femur in cranial view, and (G) femur in caudal view. Scale = 50 mm.
FigS3-AlligatorLMFigFlat2.tif
Figure S4
Figure S4. White-tailed deer (Odocoileus virginianus) landmark figures showing landmarks (numbered) and semi-landmark curves (red) for the (A) scapula, (B) humerus in cranial view, (C) humerus in medial view, (D) humerus in caudal view, (E) ilium, (F) femur in cranial view, and (G) femur in caudal view. Scale = 50 mm.
FigS4-DeerLMFigureFlat.tif
Figure S5
Figure S5. Principal component analysis of humeri (cranial view) showing the relative divergence between left and right humeri (cranial view) in morphospace for P. lujiatunensis (A), Alligator (C), and Buteo (D). Each individual is colored with a line connecting the right and left humeri (cranial view) for P. lujiatunensis and the first five specimens are given for the extant taxa, which were randomly selected. Bones were measured three times each for inclusion in the error analysis so one animal is made up of six individual points, three for the right humerus and three for the left. To identify how shape trends were affected by removing the asymmetric component of variation, we plotted thin plate splines of the symmetric component of variation for P. lujiatunesis next to thin plate splines for the total variation (B).
FigS5-FAPCAHumCranFigREVFlat.tif
Figure S6
Figure S6. Principal component analysis of humeri (medial view) showing the relative divergence between left and right humeri (medial view) in morphospace for P. lujiatunensis (A), Alligator (C), and Buteo (D). Each individual is colored with a line connecting the right and left humeri (medial view) for P. lujiatunensis and the first five specimens are given for the extant taxa, which were randomly selected. Bones were measured three times each for inclusion in the error analysis so one animal is made up of six individual points, three for the right humerus and three for the left. To identify how shape trends were affected by removing the asymmetric component of variation, we plotted thin plate splines of the symmetric component of variation for P. lujiatunesis next to thin plate splines for the total variation (B).
FigS6-FAPCAHumMedFigREVFlat.tif
Figure S7
Figure S7. Principal component analysis of humeri (caudal view) showing the relative divergence between left and right humeri (caudal view) in morphospace for P. lujiatunensis (A), Alligator (C), and Buteo (D). Each individual is colored with a line connecting the right and left humeri (caudal view) for P. lujiatunensis and the first five specimens are given for the extant taxa, which were randomly selected. Bones were measured three times each for inclusion in the error analysis so one animal is made up of six individual points, three for the right humerus and three for the left. To identify how shape trends were affected by removing the asymmetric component of variation, we plotted thin plate splines of the symmetric component of variation for P. lujiatunesis next to thin plate splines for the total variation (B).
FigS7-FAPCAHumCaudFigREVFlat.tif
Figure S8
Figure S8. Principal component analysis of ilia showing the relative divergence between left and right ilia in morphospace for P. lujiatunensis (A), Alligator (C), and Buteo (D). Each individual is colored with a line connecting the right and left ilia for P. lujiatunensis and the first five specimens are given for the extant taxa, which were randomly selected. Bones were measured three times each for inclusion in the error analysis so one animal is made up of six individual points, three for the right humerus and three for the left. To identify how shape trends were affected by removing the asymmetric component of variation, we plotted thin plate splines of the symmetric component of variation for P. lujiatunesis next to thin plate splines for the total variation (B).
FigS8-FAPCAIliaFigREVFlat.tif
Figure S9
Figure S9. Principal component analysis of femora (cranial view) showing the relative divergence between left and right femora (cranial view) in morphospace for P. lujiatunensis (A), Alligator (C), and Buteo (D). Each individual is colored with a line connecting the right and left femora (cranial view) for P. lujiatunensis and the first five specimens are given for the extant taxa, which were randomly selected. Bones were measured three times each for inclusion in the error analysis so one animal is made up of six individual points, three for the right humerus and three for the left. To identify how shape trends were affected by removing the asymmetric component of variation, we plotted thin plate splines of the symmetric component of variation for P. lujiatunesis next to thin plate splines for the total variation (B).
FigS9-FAPCAFemCranFigREVFlat.tif
Figure S10
Figure S10. Principal component analysis of femora (caudal view) showing the relative divergence between left and right femora (caudal view) in morphospace for P. lujiatunensis (A), Alligator (C), and Buteo (D). Each individual is colored with a line connecting the right and left femora (caudal view) for P. lujiatunensis and the first five specimens are given for the extant taxa, which were randomly selected. Bones were measured three times each for inclusion in the error analysis so one animal is made up of six individual points, three for the right humerus and three for the left. To identify how shape trends were affected by removing the asymmetric component of variation, we plotted thin plate splines of the symmetric component of variation for P. lujiatunesis next to thin plate splines for the total variation (B).
FigS10-FAPCAFemCaudFigREVFlat.tif
Supplemental Tables 1–9
See Main Text For Table Descriptions
Hedrick et al., Taphonomy SuppInfoREV.xlsx
