Cooksonia pertoni
- 演化之聲
- Mar 19
- 2 min read
Age
Silurian（Pridoli epoch）-Devonian（Lochkovian）
433-393 Ma
Taxonomy
Kingdom: Plantae
Superphylum: Polysporangiomorpha
Genus: Cooksonia
Species: Cooksonia pertoni
Morphological description
Cooksonia pertoni is one of the most representative species of the extinct early land plant genus Cooksonia, a group of great importance in plant evolution, although it may not form a strictly monophyletic lineage. The species was first discovered in the Perton Quarry in Wales, United Kingdom. It is characterized by terminal, trumpet-shaped sporangia with flattened tops.
The plant was small, only a few centimeters tall, and exhibited a very simple organization, lacking leaves, flowers, and true roots. The axes were smooth and cylindrical, showing dichotomous branching, with each branch terminating in a single sporangium. Some fossil specimens show dark longitudinal strands within the axis, interpreted as early water-conducting tissues.
Specimens from the Rinconada Formation in Argentina (PBSJ 1767 and 1768) are preserved as laterally compressed fossils. These include two isolated sporangia and the distal portion of the axis connecting to them. The axis measures approximately 0.38 mm in width and 1.14 mm in length, gradually widening toward the sporangium with a transitional connection. The sporangia are trumpet-shaped, about 1.77 mm wide and 1.25 mm long, with flattened features at the distal margins. Compared with other species in the genus, Cooksonia cambrensis lacks trumpet-shaped sporangia, while Cooksonia paranensis exhibits cup- or bowl-shaped sporangia with a more gradual transition between axis and sporangium.
Etymology
Cooksonia: named in honor of the Australian paleobotanist Isabel Cookson
pertoni: referring to Perton Quarry, the locality where the fossils were discovered
Biological description
Cooksonia pertoni lived from the late Silurian to the early Devonian, approximately 433 to 393 million years ago. It represents an early vascular plant within the polysporangiophytes, indicating that plants had already adapted to terrestrial environments by the late Silurian. The trumpet-shaped sporangia and their relatively straight lateral margins reflect specialization in reproductive structures.
Fossils from the Rinconada Formation in Argentina date to the late Silurian (Pridoli epoch), demonstrating that Cooksonia pertoni had already dispersed across the southwestern regions of Gondwana. This distribution suggests a degree of ecological adaptability and geographic expansion during early land plant evolution.
（Author: Shui-Ye You）
References
Lang WH. (1937). On the plant-remains from the Downtonian of England and Wales. Philosophical Transactions of the Royal Society B.
Morris JL et al. (2011). New plant taxa from the Lower Devonian (Lochkovian) of the Welsh Borderland, with a hypothesis on the relationship between hilate and trilete spore producers. Review of Palaeobotany and Palynology.
Drovandi JM et al. (2024). The southwesternmost record of late Silurian (Pridolian) early land plants of Gondwana. Scientific Reports.
52.06, -2.59
49, 27.5
31.73, 68.67
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