John A. Breyer, Arthur B. Busbey, Richard E. Hanson, Edward C. Roy; Possible new evidence for the origin of metazoans prior to 1 Ga: Sediment-filled tubes from the Mesoproterozoic Allamoore Formation, Trans-Pecos Texas. Geology ; 23 (3): 269–272. doi: https://doi.org/10.1130/0091-7613(1995)023<0269:PNEFTO>2.3.CO;2
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Possible new evidence for the origin of metazoans prior to 1 Ga comes from sediment-filled tubes preserved on a bedding-plane parting in a chert in the Allamoore Formation (Mesoproterozoic) in a talc quarry in the Millican Hills, near Van Horn, Trans-Pecos Texas. Available data for the Van Horn region indicate that the age of the Allamoore Formation is ∼1250 Ma. The sediment-filled tubes are most likely the feeding traces of animals grazing on algal mats in shallow subtidal or intertidal environments.