Do tracks yield reliable information on gaits? – Part 1: The case of horses

K Kienapfel,H Preuschoft,S Läbe

doi:10.5194/fr-17-59-2014

K Kienapfel, H Preuschoft + Show 1 more

Open Access

https://doi.org/10.5194/fr-17-59-2014

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Journal: Fossil Record	Publication Date: Mar 28, 2014
Citations: 14	License type: CC BY 3.0

Affiliation: Ruhr University Bochum, University of Bonn

Abstract

Abstract. During their lifetime animals leave many tracks and traces behind, which can provide insights into the animals' behaviour. Single footprints of extant vertebrates are frequently found in sediments all over the world, often arranged into trackways. The study of footprints and trackways lead to interpretations about the mode of locomotion of the trackmaker. Here we show an approach to identify gaits from tracks. A series of experiments with horses was performed to determine whether gaits could be identified on the basis of fossil trackways, e.g. those left behind by sauropod dinosaurs of the Mesozoic era or Tertiary mammals, to unveil their locomotor abilities. The generally valid rules for quadrupedal locomotion were taken into consideration. Symmetrical gaits result in very similar trackways; a further differentiation can be made by application of statistics on step lengths, excursion angles and overstepping. A clear difference exists between the trot and the pace. These rapid, symmetric gaits imply high ground reaction forces (GRF) because of their long phases of aerial suspension at higher speeds. The resulting GRF seem to be too high to be sustained by the limb bones of huge graviportal animals like sauropods. Unfortunately, most of these factors are rarely available in the case of fossil tracks. Likewise, the asymmetrical, springing gaits can be excluded for sauropods because of the enormous GRF. Provided that limb length as well as trunk length can be approximated, and left and right, as well as forefoot and hindfoot imprints can be discriminated, the symmetrical gaits (walk, amble, pace, trot) used when making a trackway can be discerned.

Highlights

Footprints of extinct animals are quite common in earth history and can be found in sedimentary rocks all over the world, often arranged into trackways of many metres in length
One aim of research on footprints and trackways is to apply and to verify a soil mechanical concept to predict the weight of the trackmaker and the direction and shifting of ground reaction forces (GRF) (Schanz et al, 2013), using footprint geometry and the soil mechanical properties of the subsoil by application of finite element analysis
Provided that the size of the trackmaker is known or can be approximated, in particular concerning lengths of limbs in relation to trunk length, the “symmetrical gaits” walk and amble can be discriminated from trot or pace

Summary

Introduction

Footprints of extinct animals are quite common in earth history and can be found in sedimentary rocks all over the world, often arranged into trackways of many metres in length. One aim of research on footprints and trackways is to apply and to verify a soil mechanical concept to predict the weight of the trackmaker and the direction and shifting of ground reaction forces (GRF) (Schanz et al, 2013), using footprint geometry and the soil mechanical properties of the subsoil by application of finite element analysis. Another aim is to apply our knowledge of the mode of locomotion of extant taxa on the footfall pattern in trackways of extinct taxa and to estimate gait as postulated by Thompson et al (2007).

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