Skip to main content
Dryad logo

3D skeletal pelvic landmarks from anthropoid primates

Citation

Moffett, Elizabeth (2021), 3D skeletal pelvic landmarks from anthropoid primates, Dryad, Dataset, https://doi.org/10.5061/dryad.tqjq2bvzq

Abstract

Objectives: The presence of sexual dimorphism in the birth canals of anthropoid primates is well-documented, and birth canal dimorphism tends to be especially robust among species that give birth to relatively large neonates. However, it is less clear whether birth canal dimorphism is accompanied by dimorphism in parts of the pelvis not directly under selection for birth, particularly including bi-iliac breadth, biactetabular breadth, lengths of the ischium and ilium, and 3D shape. This study investigates the patterns of dimorphism among anthropoid primates in those parts of the pelvis which do not directly contribute to the bony birth canal, here termed the non-obstetric pelvis.

Methods: 3D landmark data were collected on the bony pelves of 899 anthropoid primates. Specifically, landmark data were collected on parts of the pelvis not thought to be directly involved in selection for parturition, including portions of the posterior and superior ilium, acetabulum, and lateral ischium. principal components analysis and Euclidean distance matrix analysis were used to ascertain sexual dimorphism in pelvic sizes and shapes within each species.

Results: Results show that dimorphism in non-obstetric pelvic size and shape exists across anthropoids, just as is seen in the birth canal. However, the magnitude of dimorphism in non-obstetric pelvic shape tends to be greater among anthropoid species that give birth to relatively large neonates compared to those birthing smaller neonates relative to maternal pelvic size.

Conclusions: Though all anthropoids included in the study show some degree of sexual dimorphism in non-obstetric pelvic size and/or shape, species which give birth to large neonates relative to maternal pelvic size have the highest levels of dimorphism in pelvic shape. Moreover, the magnitude of dimorphism in certain parts of the non-obstetric pelvis mirrors patterns seen in the birth canal. The results of this study are promising for ascertaining pelvic dimorphism and relative neonate size in fossil primates, particularly in fragmentary remains which do not preserve a complete bony birth canal.

Methods

The 3D coordinates in this dataset were collected using a Microscribe MX 3D Digitizer. The dataset included here are the raw landmark data for each specimen. Skeletal pelves were articulated using putty and rubber bands, and the following landmarks were collected:  

Landmark #  Landmark Title Description
1 L PIIS Left Posterior Inferior Iliac Spine
2 L PSIS Left Posterior Superior Iliac Spine
3 L sup iliac crest Left superior-most point on iliac crest
4 L ASIS Left Anterior Superior Iliac Spine
5 L lat SI joint Left lateral-most point on SI joint
6 L arcuate SI ilium Left intersection of arcuate line & SI joint
7 L lateral arcuate line Left lateral-most point on arcuate line
8 L ant iliac neck Left narrowest point along the anterior iliac neck
9 L dors iliac neck Left narrowest point along the posterior iliac neck
10 L pubis arcuate line Left intersection of pubis & ilium on arcuate line
11 L pub acetabulum Left intersection of pubis & ilium on acetabular rim
12 L sup acetab Left superior-most point on acetabular rim
13 L dorsal acetab Left dorsal-most point on acetabular rim
14 L caudal acetab Left caudal-most point on acetabular rim
15 L acetab center Left center of acetabular fossa
16 L dorsal acetab isch Left intersection of ilium and ischium posterior to acetabulum
17 L ischial spine Left ischial spine along medial-most point
18 L post ishial ramus Left narrowest point along the posterior ischial ramus
19 L post tuberosity Left posterior-most point along ischial tuberosity
20 L ant tuberosity Left anterior-most point along ischial tuberosity
21 L lat ischial ramus Left lateral point along deepest curve of ischial ramus
22 L obt ischial ramus Left inferior-most point along ischiopubic ramus
23 inf pub symphysis Midline Inferior-most point on pubic symphysis
24 sup pub symphysis Midline superior-most point on pubic symphysis
25 dorsal S1 Midline dorsal point on S1 vertebral body
26 ventral S1 Midline ventral point on S1 vertebral body
27 left S1 Left lateral-most point on S1 vertebral body
28 left sup ala Left lateral-most point on superior sacral ala
29 inf S1 Midline junction of S1-S2
30 inf S2 Midline junction of S2-S3
31 inf Sacrum Midline inferior-most point on sacrum
32 right S1 Right lateral-most point on S1 vertebral body
33 right sup ala Right lateral-most point on superior sacral ala
34 R PIIS Right Posterior Inferior Iliac Spine
35 R PSIS Right Posterior Superior Iliac Spine
36 R sup iliac crest Right superior-most point on iliac crest
37 R ASIS Right Anterior Superior Iliac Spine
38 R lat SI joint Right lateral-most point on SI joint
39 R lateral arcuate line Right lateral-most point on arcuate line
40 R ant iliac neck Right narrowest point along the anterior iliac neck
41 R dorsal iliac neck Right narrowest point along the posterior iliac neck
42 R pubis arcuate line Right intersection of pubis & ilium on arcuate line
43 R pub acetab Right intersection of pubis & ilium on acetabular rim
44 R sup acetab Right superior-most point on acetabular rim
45 R dorsal acetab Right dorsal-most point on acetabular rim
46 R caudal acetab Right caudal-most point on acetabular rim
47 R acetab center Right center of acetabular fossa
48 R dorsal acetab isch Right intersection of ilium and ischium posterior to acetabulum
49 R ischial spine Right ischial spine along medial-most point
50 R post ishial ramus Right narrowest point along the posterior ischial ramus
51 R post tuberosity Right posterior-most point along ischial tuberosity
52 R ant tuberosity Right anterior-most point along ischial tuberosity
53 R lat ischial ramus Right lateral point along deepest curve of ischial ramus
54 R obt ischial ramus Right inferior-most point along ischiopubic ramus

The following link is a figure depicting the location of each landmark collection location (only the left side is shown for bilaterally collected landmarks):

https://docs.google.com/document/d/1CJvDDgeio2lVgV32lewatqEBzdR6SIrGD01tIdu1_-4/edit?usp=sharing

 

Usage Notes

The dataset included here has 921 specimens, as some sample sizes collected were too small for sufficient power to include in the published AJPA article. However, these extra specimens are included in the dataset for completeness.

Funding

Louis B. Leakey Foundation

Wenner-Gren Foundation

Louis B. Leakey Foundation