Tortilicaulis
Encyclopedia
Tortilicaulis is a moss
-like plant
known from fossil
s recovered from southern Britain, spanning the Silurian-Devonian boundary (around ). Originally recovered from the Downtonian of the Welsh
borderlands, Tortilicaulis has since been recovered in the famous Ludlow Lane locality.
Whilst it is generally accepted that Tortilicaulis was moss-like, it has not yet been recovered in a sufficiently good state of preservation to allow the detailed study necessary to firmly assign it to a taxonomic group. Fossils consist of an elongate apical sporangium
(spore-forming organ), which may be branched, with spiralled walls attached to an undivided stalk that is also twisted. Unusually for plants of its time, spores of Tortilicaulis were covered all over with small granules.
The initial suspicions of its describer, Dianne Edwards
, were that it was a bryophyte
, and comparisons have been made with several groups. A potential association with the moss Takakia
is supported by features of the sporangia
, such as the elongate shape, unusual twisting, and terminal position of the sporangia
.
As the sporangia of Tortilicaulis are branched, cladistic analysis suggests that the genus may instead belong to the Horneophytopsida
, a class
of the polysporangiophyte
s, which unlike bryophytes, have branched stems bearing sporangia. Its precise nature and hence classification remains unclear. For the cladogram, see the Horneophytopsida
article.
Moss
Mosses are small, soft plants that are typically 1–10 cm tall, though some species are much larger. They commonly grow close together in clumps or mats in damp or shady locations. They do not have flowers or seeds, and their simple leaves cover the thin wiry stems...
-like plant
Plant
Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...
known from fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s recovered from southern Britain, spanning the Silurian-Devonian boundary (around ). Originally recovered from the Downtonian of the Welsh
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
borderlands, Tortilicaulis has since been recovered in the famous Ludlow Lane locality.
Whilst it is generally accepted that Tortilicaulis was moss-like, it has not yet been recovered in a sufficiently good state of preservation to allow the detailed study necessary to firmly assign it to a taxonomic group. Fossils consist of an elongate apical sporangium
Sporangium
A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle...
(spore-forming organ), which may be branched, with spiralled walls attached to an undivided stalk that is also twisted. Unusually for plants of its time, spores of Tortilicaulis were covered all over with small granules.
The initial suspicions of its describer, Dianne Edwards
Dianne Edwards
Dianne Edwards CBE ScD FRSE FLSW FRS is a palaeobotanist, who studies the colonisation of land by plants, and early land plant interactions.-Career:...
, were that it was a bryophyte
Bryophyte
Bryophyte is a traditional name used to refer to all embryophytes that do not have true vascular tissue and are therefore called 'non-vascular plants'. Some bryophytes do have specialized tissues for the transport of water; however since these do not contain lignin, they are not considered to be...
, and comparisons have been made with several groups. A potential association with the moss Takakia
Takakia
Takakia is a genus of two species of moss known from western North America and central and eastern Asia. The genus is placed as a separate family, order and class among the mosses...
is supported by features of the sporangia
Sporangium
A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle...
, such as the elongate shape, unusual twisting, and terminal position of the sporangia
Sporangium
A sporangium is an enclosure in which spores are formed. It can be composed of a single cell or can be multicellular. All plants, fungi, and many other lineages form sporangia at some point in their life cycle...
.
As the sporangia of Tortilicaulis are branched, cladistic analysis suggests that the genus may instead belong to the Horneophytopsida
Horneophytopsida
Horneophytopsida is a class of extinct plants which consisted of branched stems without leaves, true roots or vascular tissue, found from the Late Silurian to the Early Devonian . They are the simplest known polysporangiophytes, i.e. plants with sporophytes bearing many spore-forming organs on...
, a class
Class (biology)
In biological classification, class is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, order, family, genus, and species, with class fitting between phylum and order...
of the polysporangiophyte
Polysporangiophyte
Polysporangiophytes, also called polysporangiates or more formally Polysporangiophyta, are plants in which the spore-bearing generation has a structure of branching stems terminating in sporangia...
s, which unlike bryophytes, have branched stems bearing sporangia. Its precise nature and hence classification remains unclear. For the cladogram, see the Horneophytopsida
Horneophytopsida
Horneophytopsida is a class of extinct plants which consisted of branched stems without leaves, true roots or vascular tissue, found from the Late Silurian to the Early Devonian . They are the simplest known polysporangiophytes, i.e. plants with sporophytes bearing many spore-forming organs on...
article.