Visualization of a Juvenile Australopithecus afarensis Specimen: Implications for Functional Foot Anatomy

Abstract

Since it was named in 1978, analyses of Australopithecus afarensis have culminated in several dominant theories on how humans acquired many of their unique adaptations. Because bipedal locomotion is one of the earliest characteristics of human functional anatomy to appear in the fossil record, its associated anatomy in early hominins has significant implications for human evolution (Stern 2000). The skeleton and overall morphological characteristics of the foot in Australopithecus afarensis provide important clues about the origins of upright bipedal locomotion. Popularly known as "Selam," the 3.3 million-year-old DIK-1-1 fossil was discovered in Dikika, Ethiopia by Dr. Zeresenay Alemseged and his team in 2000. Selam was an australopithecine who died at three years old, making her the youngest early hominin specimen known today (Alemseged et al. 2006). This discovery allows researchers to investigate not only locomotor patterns of A. afarensis within the context of human evolution, but also to examine what child development may have looked like during this pivotal time. The purpose of this project is to create a 3D animation that accurately reconstructs the anatomy and taphonomy of the Dikika foot. By segmenting CT data, 3D modelling, and animating, this investigation aims to contribute to the breadth of fossil reconstruction techniques in the field of biomedical visualization. This method provides a robust means of communication within, and beyond, the paleoanthropological community about new discoveries and how to visualize them.

Keywords: 3D animation; Australopithecus afarensis; fossil; human evolution; paleoanthropology; segmentation.

Figure 1

3D visualization from CT data of modern human 11-year old foot skeleton with bones indicated.

Figure 2

3D render of segmented CT data from Dikika foot fossil.

Figure 3

Avizo segmentation interface with 3D, coronal, transverse, and sagittal views of Dikika fossil foot depicted. The calcaneus is in the process of segmentation.

Figure 4

Lateral view of the segmented models in 3ds Max (A) before and (B) after the retopologization process.

Figure 5

Retopologization interface in Pixologic ZBrush.

Figure 6

Storyboard page 4 depicting ending transition from 3D into 2D in the final third of the animation. Blue lines indicate camera transitions and movements.

Figure 7

Human foot skeleton undergoing retouching process in Pixologic ZBrush, (A) anteromedial and (B) medial views.

Figure 8

Human foot skeleton in 3ds Max, with (A) surface topology and (B) wireframe shown.

Figure 9

Initial placement of human metatarsals and phalanges as placeholders for missing elements of Dikika foot skeleton in (A) medial and (B) superior views.

Figure 10

Screenshot of footage-editing interface in Adobe After Effects. This photo depicts the sifting of fossil-bearing material through a screen mesh.

Figure 11

Early test render of lighting setup in 3ds Max.

Figure 12

Screen capture of exploded Dikika foot skeleton.

Figure 13

Screen capture of composited scene with comparison between the human (left) and Dikika foot (right) skeletons.

Figure 14

Screen capture of labels for the metatarsals, tarsals, and phalanges of the Dikika foot skeleton.