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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

Impressions left by P. annectens on soft mud.The body has failed to leave any markings, while the open mouth has produced two distinct double impressions, followed by a single mark. Direction of travel is towards the upper left of the image. Scale bar = 10 cm, colour scale ranges from blue (low) to red (high) over 10 mm.
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f4: Impressions left by P. annectens on soft mud.The body has failed to leave any markings, while the open mouth has produced two distinct double impressions, followed by a single mark. Direction of travel is towards the upper left of the image. Scale bar = 10 cm, colour scale ranges from blue (low) to red (high) over 10 mm.

Mentions: As the lungfish moved forward, it left behind an alternating left-right sequence of head impressions (Figs 2, 3, 4 and 5). The impressions were variable in their distance from each other, (1–15 cm) but generally occurred ~10 cm apart (Figs 2, 3, 4 and 5). Between these impressions were occasional shallow sinuous markings produced by the body and fins of the animal, though such markings only substantially appeared in 2 of the trials on mud (Fig. 3), and in this case the animal was observed slipping during the pivoting manoeuvre. On sand no such markings were observed (see below). The fins were not observed to have any role in the lungfish’s locomotion. On the mud substrate, cohesion meant the pectoral fins often adhered to the trunk of the animal. Any trails left by the paired fins were a result of incidental motion against a very soft substrate.


Trackways Produced by Lungfish During Terrestrial Locomotion
Impressions left by P. annectens on soft mud.The body has failed to leave any markings, while the open mouth has produced two distinct double impressions, followed by a single mark. Direction of travel is towards the upper left of the image. Scale bar = 10 cm, colour scale ranges from blue (low) to red (high) over 10 mm.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f4: Impressions left by P. annectens on soft mud.The body has failed to leave any markings, while the open mouth has produced two distinct double impressions, followed by a single mark. Direction of travel is towards the upper left of the image. Scale bar = 10 cm, colour scale ranges from blue (low) to red (high) over 10 mm.
Mentions: As the lungfish moved forward, it left behind an alternating left-right sequence of head impressions (Figs 2, 3, 4 and 5). The impressions were variable in their distance from each other, (1–15 cm) but generally occurred ~10 cm apart (Figs 2, 3, 4 and 5). Between these impressions were occasional shallow sinuous markings produced by the body and fins of the animal, though such markings only substantially appeared in 2 of the trials on mud (Fig. 3), and in this case the animal was observed slipping during the pivoting manoeuvre. On sand no such markings were observed (see below). The fins were not observed to have any role in the lungfish’s locomotion. On the mud substrate, cohesion meant the pectoral fins often adhered to the trunk of the animal. Any trails left by the paired fins were a result of incidental motion against a very soft substrate.

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