Herpetogaster collinsi

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A creeping organism with tentacles and a long stalk

3D animation of Herpetogaster collinsi.

Animation by Phlesch Bubble © Royal Ontario Museum

Herpetogaster collinsi (ROM 58037) – Part and counterpart. Complete specimen preserved laterally showing tentacles and stolon with terminal disk. Specimen length (with tentacles) = 38 mm. Specimen dry – polarized light. Raymond Quarry.

Herpetogaster collinsi (ROM 58039) – Part and counterpart. Complete specimen with well preserved gut associated with an unidentified ball-shaped object. Specimen length (with tentacles) = 32 mm. Specimen dry – polarized light. Raymond Quarry.

Herpetogaster collinsi (ROM 58046) – Part (top row) and counterpart (bottom row). Complete specimen preserved dorso-ventrally showing well preserved tentacles. Specimen length (with tentacles) = 30 mm. Specimen wet – direct light (left column), wet – polarized light (right column). Raymond Quarry.

Herpetogaster collinsi (ROM 58047) – Part (top row) and counterpart (bottom row). Complete specimen preserved laterally showing elongated stolon and terminal disk. Specimen length (with tentacles and stolon) = 38 mm. Specimen dry – polarized light (left column), wet – polarized light (right column). Raymond Quarry.

Herpetogaster collinsi (ROM 58051) – Holotype, part (top row) and counterpart (bottom row). Complete specimen preserved dorso-ventrally showing tentacles, stolon and large reflective stomach (in direct light). Specimen length (with tentacles) = 46 mm. Specimen dry – polarized light (left), wet – polarized light (middle), wet – direct light (right). Raymond Quarry.

Herpetogaster collinsi (ROM 58058) – Part and counterpart. Complete specimen preserved dorso-ventrally showing twisted stolon and terminal disk attached to the sponge Vauxia. Specimen length (with tentacles and stolon) = 35 mm. Specimen wet – polarized light. Raymond Quarry.

Herpetogaster collinsi (ROM 58084) – Part and counterpart. Slab with several specimens associated with the sponge Vauxia. Right column, close up of a specimen (see white frame) with part of the stolon attached to sponge spicules. Cluster width = 120 mm. Specimen wet – direct light (left column and bottom right image), wet – polarized light (middle column, and middle right image), dry – polarized light (top right image). Raymond Quarry.

Taxonomy:

Kingdom: Animalia

Phylum: Unknown

Higher Taxonomic assignment: Unranked clade Cambroernida (stem group ambulacrarians)

Species name: Herpetogaster collinsi

Remarks:

Herpetogaster, together with other pedunculate or discoidal fossils such as Eldonia, probably belongs in the stem group to a clade known as the Ambulacraria, represented by both echinoderms and hemichordates (Caron et al., 2010).

Described by: Caron and Conway Morris

Description date: 2010

Etymology:

Herpetogaster – from the Greek, herpo, “to creep,” and gaster, “stomach.” The name refers to the creeping aspect of the animal and the large stomach.

collinsi – after Desmond Collins, a former curator of palaeontology at the Royal Ontario Museum who led expeditions to the Burgess Shale between 1975-2000.

Type Specimens: Holotype –ROM58051 in the Royal Ontario Museum, Toronto, Canada.

Other species:

Burgess Shale and vicinity: none.

Other deposits: none.

Age & Localities:

Age:

Middle Cambrian, Bathyuriscus-Elrathina Zone (approximately 505 million years ago).

Principal localities:

The Walcott and Raymond Quarries on Fossil Ridge. The Collins Quarry on Mount Stephen and Stanley Glacier in Kootenay National Park.

History of Research:

Brief history of research:

Herpetogaster was described in 2010 as a possible member of the ambulacrarians (Caron and Conway Morris, 2010).

Description:

Morphology:

Herpetogaster consists of a main body with a pair of tentacles at the front and a flexible stolon. The body is divided into thirteen segments and coils clockwise when seen dorsally. The tentacles are long and flexible and branch several times. The stomach is the most conspicuous portion of the gut and is often preserved as a highly reflective film, as in Eldonia, a closely related form. The anus is terminal and the mouth is located between the tentacles. The stolon sometimes exceeds the length of the main body, and terminates with a flat disk. This structure was evidently used for anchoring the organism to the seabed, or to other organisms).

Abundance:

This animal is known from 101 specimens. Only 6 come from the Walcott Quarry, where it represents only 0.011% of the specimens counted in the community (Caron and Jackson, 2008); most specimens (68) come from the Raymond Quarry.

Maximum Size:

48 mm

Ecology:

Life habits: Epibenthic, Mobile

Feeding strategies: Suspension feeder, Carnivorous

Ecological Interpretations:

Specimens of Herpetogaster were found associated with the sponge Vauxia, suggesting the animal lived on or near the seabed. It is not clear if Herpetogaster was permanently anchored, and whether or not it fed only on particulate matter in the water column, or could hunt small preys using its prehensile tentacles.

References:

CARON, J.-B. AND D. A. JACKSON. 2008. Paleoecology of the Greater Phyllopod Bed community, Burgess Shale. Palaeogeography, Palaeoclimatology, Palaeoecology, 258: 222-256.

CARON, J.-B., S. CONWAY MORRIS AND D. SHU. 2010. Tentaculate fossils from the Cambrian of Canada (British Columbia) and China (Yunnan) interpreted as primitive deuterostomes. PLoS ONE, 5(3): e9586.