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Trackways Produced by Lungfish During Terrestrial Locomotion

View Article: PubMed Central - PubMed

ABSTRACT

Some primarily aquatic vertebrates make brief forays onto land, creating traces as they do. A lack of studies on aquatic trackmakers raises the possibility that such traces may be ignored or misidentified in the fossil record. Several terrestrial Actinopterygian and Sarcopterygian species have previously been proposed as possible models for ancestral tetrapod locomotion, despite extant fishes being quite distinct from Devonian fishes, both morphologically and phylogenetically. Although locomotion has been well-studied in some of these taxa, trackway production has not. We recorded terrestrial locomotion of a 35 cm African lungfish (Protopterus annectens; Dipnoi: Sarcopterygii) on compliant sediment. Terrestrial movement in the lungfish is accomplished by planting the head and then pivoting the trunk. Impressions are formed where the head impacts the substrate, while the body and fins produce few traces. The head leaves a series of alternating left-right impressions, where each impact can appear as two separate semi-circular impressions created by the upper and lower jaws, bearing some similarity to fossil traces interpreted as footprints. Further studies of trackways of extant terrestrial fishes are necessary to understand the behavioural repertoire that may be represented in the fossil track record.

No MeSH data available.


Related in: MedlinePlus

Outline images of the motion of P. annectens traversing soft mud.The head is planted into the sediment, and used as a pivot around which to arch the body. The process is then repeated by planting the head to the other side. Depending on the consistency of the mud, either a single impression is left, or two impressions are formed from the upper and lower mouth parts.
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f1: Outline images of the motion of P. annectens traversing soft mud.The head is planted into the sediment, and used as a pivot around which to arch the body. The process is then repeated by planting the head to the other side. Depending on the consistency of the mud, either a single impression is left, or two impressions are formed from the upper and lower mouth parts.

Mentions: For each trial (total utilised trials = 10), the lungfish was placed in the centre of the substrate tray and allowed to move in any direction. Generally, the animal moved in the direction it was placed and proceeded at a rate of ~1–2 cm/s. Speed was consistently slow, even when attempts were made to elicit faster locomotion. As the lungfish traversed the compliant substrate, it did so by planting the head into the surface of the sediment, and then pivoting the rest of the body forwards (Fig. 1, Supplemental movies 1 and 2). During continuous movement, these motions occurred at a rate of ~0.25 cycles per second (that is, ~4 seconds between head plants). This ‘head-crutching’ behaviour is stereotypic and has been observed in many individuals (AMH pers. obv., 200523); details of the kinematics and axial muscle activity of terrestrial locomotion in P. annectens are available from the literature23. Head plants alternated between the fish’s left and right sides between cycles, and the majority of the lungfish’s body left very little impression in the surface. The head itself, which was forced down to provide an anchor around which to pivot the body, produced a significant depression (2–9 mm deep).


Trackways Produced by Lungfish During Terrestrial Locomotion
Outline images of the motion of P. annectens traversing soft mud.The head is planted into the sediment, and used as a pivot around which to arch the body. The process is then repeated by planting the head to the other side. Depending on the consistency of the mud, either a single impression is left, or two impressions are formed from the upper and lower mouth parts.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037403&req=5

f1: Outline images of the motion of P. annectens traversing soft mud.The head is planted into the sediment, and used as a pivot around which to arch the body. The process is then repeated by planting the head to the other side. Depending on the consistency of the mud, either a single impression is left, or two impressions are formed from the upper and lower mouth parts.
Mentions: For each trial (total utilised trials = 10), the lungfish was placed in the centre of the substrate tray and allowed to move in any direction. Generally, the animal moved in the direction it was placed and proceeded at a rate of ~1–2 cm/s. Speed was consistently slow, even when attempts were made to elicit faster locomotion. As the lungfish traversed the compliant substrate, it did so by planting the head into the surface of the sediment, and then pivoting the rest of the body forwards (Fig. 1, Supplemental movies 1 and 2). During continuous movement, these motions occurred at a rate of ~0.25 cycles per second (that is, ~4 seconds between head plants). This ‘head-crutching’ behaviour is stereotypic and has been observed in many individuals (AMH pers. obv., 200523); details of the kinematics and axial muscle activity of terrestrial locomotion in P. annectens are available from the literature23. Head plants alternated between the fish’s left and right sides between cycles, and the majority of the lungfish’s body left very little impression in the surface. The head itself, which was forced down to provide an anchor around which to pivot the body, produced a significant depression (2–9 mm deep).

View Article: PubMed Central - PubMed

ABSTRACT

Some primarily aquatic vertebrates make brief forays onto land, creating traces as they do. A lack of studies on aquatic trackmakers raises the possibility that such traces may be ignored or misidentified in the fossil record. Several terrestrial Actinopterygian and Sarcopterygian species have previously been proposed as possible models for ancestral tetrapod locomotion, despite extant fishes being quite distinct from Devonian fishes, both morphologically and phylogenetically. Although locomotion has been well-studied in some of these taxa, trackway production has not. We recorded terrestrial locomotion of a 35 cm African lungfish (Protopterus annectens; Dipnoi: Sarcopterygii) on compliant sediment. Terrestrial movement in the lungfish is accomplished by planting the head and then pivoting the trunk. Impressions are formed where the head impacts the substrate, while the body and fins produce few traces. The head leaves a series of alternating left-right impressions, where each impact can appear as two separate semi-circular impressions created by the upper and lower jaws, bearing some similarity to fossil traces interpreted as footprints. Further studies of trackways of extant terrestrial fishes are necessary to understand the behavioural repertoire that may be represented in the fossil track record.

No MeSH data available.


Related in: MedlinePlus