Siphonia (Siphonia) pyriformis

Overview

Siphonia pyriformis is a sponge studied from Late Cretaceous specimens in Poland. The five specimens studied are described as rounded and showing no trace of a stalk. A large upper opening and small surface openings reveal different structures.^[1]

Key facts

The five specimens are described as lacking traces of a stalk or an attachment site. Considering this small specimen group separately distinguishes it from other shapes associated with the name Siphonia. This shows why it matters which specimens were examined when describing a fossil.^[1]

Time and place

The selected specimen group is Late Cretaceous material from present-day Poland. The Cretaceous was roughly 140–66 million years ago. Specimen descriptions in the 1966 study provide clues for understanding this rounded sponge’s body.^[1][2]

The time range describes source context, not the complete duration of this species.

Size, form and skeleton

The body is rounded, with an osculum, or water outlet, described at the top. A central cavity and small openings on the outer surface are also explained. You can move from the broad outline to the inner space and then to small surface structures.^[1]

The Siphonia pyriformis specimens described from Poland have a rounded form with a cross section of 24×35mm. At the top of the body is a water outlet 8mm in diameter, leading into a tubular space 23mm deep.^[3]

Habitat and reproduction

The large and small openings in a sponge body occupy different positions. In this specimen group, the upper osculum is distinguished from small surface openings. Looking beyond the rounded exterior prompts consideration of the body’s pathways for water entering and leaving.^[1]

Fossil discovery

Hurcewicz described these specimens in a 1966 study of siliceous sponges from Poland. The account noted the rounded bodies of five specimens and whether stalk traces were present. This study recorded the appearance of a group through careful comparison of a few specimens.^[1]

References

1. Hurcewicz (1966) — Five Siphonia specimens from Poland
2. International Commission on Stratigraphy (2024) — Geological time chart
3. Hurcewicz (1966), Siliceous sponges from the Upper Cretaceous of Poland, Part I: Tetraxonia
4. Jurkowska et al. (2015) — Porosphaera fossils from Poland
5. Wilmsen et al. (2012) — Porosphaera fossils from Iran

Research questions

How can the top and bottom of a rounded fossil be recognized? Researchers separately examined the upper osculum and attachment traces on the lower surface. Establishing body orientation leads to questions about reading small surface structures.^[1]

Observation

Move your gaze from the rounded overall outline to the large opening at the top. Comparing it with small surface openings reveals differently sized structures within one body.^[1]