Caytonia nathorstii
- Rodrigo
- Mar 19
- 2 min read
Age
Jurassic（Hettangian-Tithonian）
145-200 Ma
Taxonomy
Kingdom: Plantae
Phylum: Pteridospermatophyta
Class: Caytoniopsida
Order: Caytoniales
Family: Caytoniaceae
Genus: Caytonia
Species: Caytonia nathorstii
Morphological description
The ovuliferous organs of Caytonia nathorstii consist of numerous small, cup-shaped structures known as cupules. Each cupule bears one to several ovules arranged within it. These cupules are closely packed together, forming a spike-like aggregate. In shape, they range from elliptical to nearly spherical, with a distinct venation pattern on the outer wall and fine vascular networks visible on the surface. The ovules are typically anatropous, positioned inside the cupule, with the micropyle oriented upward.
The supporting stalk is slender and connects to a more robust fructifying axis, showing clear bilateral symmetry. Evidence from fossil impressions and cuticular structures indicates that the epidermal cells of the fruiting organs are regularly arranged and possess guard cells and stomatal features. These characteristics make it one of the most representative types of ovuliferous structures within the order Caytoniales.
Etymology
The genus name Caytonia is derived from Cayton Bay in North Yorkshire, England, where these fossils were first discovered and described. The suffix '-ia' is a Latinized ending commonly used in plant genus names, indicating association with a particular locality.
The species name nathorstii honors the Swedish palaeobotanist Alfred Gabriel Nathorst (1850–1921), who made significant contributions to the study of Mesozoic plants, particularly seed ferns. Thus, the name Caytonia nathorstii signifies a plant from Cayton Bay named in tribute to Nathorst.
Biological description
From a palaeoecological perspective, Caytonia nathorstii is regarded as an important representative of seed ferns in Middle Jurassic Europe. Its reproductive features suggest that pollination may have been facilitated by wind or small animals. The orientation of the micropyle toward the opening of the cupule would have allowed pollen to enter efficiently and reach the ovules.
The cupulate structure shows functional similarities to the carpel of angiosperms, a feature that has long attracted attention regarding its potential evolutionary relationship with flowering plants. The foliage of this plant is typically associated with the genus Sagenopteris, while its pollen-producing organs correspond to Caytonanthus, together forming a complete seed fern plant.
Fossil assemblages from Jurassic deposits in Yorkshire indicate that this plant inhabited humid environments, likely growing along riverbanks or in low-lying forested areas. Within these ecosystems, it probably formed a significant component of the local vegetation.
（Author: Rodrigo）
Reference
Xu, Q., Wang, Y., Hilton, J., & Zhu, J. (2024). Revision of Sagenopteris (Caytoniales), a major lineage of the Mesozoic seed plants. Papers in Palaeontology, 10(3), e1575. https://doi.org/10.1002/spp2.1575
54.24, -0.36
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