Organism · Animals
Dendrograptus hallianus
Fossil record age bounds · ≈ 497–477 Ma
Inferred life reconstruction
Dendrograptus hallianus
Overview
Dendrograptus hallianus is a colonial graptolite whose tubular skeleton spreads like a fan. Follow its irregularly branching stems and the rows of small tubes beside them to examine its distinctive arrangement.[1]
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Key facts
Old illustrations and later specimens connect our view of the same organism. The reference specimen CMC IP83197, studied later, has repeatedly appeared in research as evidence of the fan-shaped colony’s features.[1]
Time and place
The Afton specimens presented in the research come from the Late Cambrian Potsdam Sandstone and St Lawrence Formation. The locality is Afton in present-day Minnesota, USA. Colony fragments preserved in ancient strata convey its form.[1]
The time range describes source context, not the complete duration of this species.
Size, form and skeleton
The colony is fan-shaped, with irregularly dividing branches. Small tubes called autothecae form rows visible from the side. Its characteristic form spreads without cross-connections joining the branches.[1]
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Habitat and reproduction
The study classifies the Dendrograptidae, the family containing this species, as bottom-dwelling marine graptolites. Graptolites included not only groups drifting in the sea but also groups inhabiting the seabed.[1]
Fossil discovery
Prout illustrated two small fragments of this form in 1851. Afton specimens later collected by C. R. Stauffer provided evidence for understanding the colonial arrangement.[1]
References
Research questions
A 2026 study compared flattened graptolites with three-dimensionally preserved material to examine tube arrangements. The way small tubes connect is an important clue for distinguishing similar colonies.[1]
Observation
The illustration depicts a colony fragment of the preserved tubular skeleton. Move your gaze from one branch to another and look for rows of small tubes along their sides.[1]
Related organisms
Diplacanthograptus spiniferusAnimalsFossil record age bounds · ≈ 453–445 MaComparing graptolite colonies from different times
Late Cambrian Dendrograptus and Ordovician Diplacanthograptus show colonial graptolite skeletons from different times. Branches spread like a fan in the Dendrograptus fragment, while small tubes repeat along a long, slender outline in the illustration of Diplacanthograptus. Examine their branching patterns and tube arrangements side by side.