''Thyrsopteris'' is a genus of

tree fern Tree ferns are arborescent (tree-like) ferns that grow with a trunk (botany), trunk elevating the fronds above ground level, making them trees. Many extant tree ferns are members of the order Cyatheales, to which belong the families Cyatheaceae ( ...

. It contains a single living species, ''Thyrsopteris elegans'', endemic to the

Juan Fernandez Archipelago ''Juan'' is a given name, the Spanish and Manx versions of ''John''. The name is of Hebrew origin and has the meaning "God has been gracious." It is very common in Spain and in other Spanish-speaking countries around the world and in the Philippi ...

off the coast of Chile. ''Thyrsopteris'' is the only genus in the family Thyrsopteridaceae in the

Pteridophyte Phylogeny Group The Pteridophyte Phylogeny Group (PPG) is an informal international group of systematic botanists who collaborate to establish on the classification of pteridophytes ( lycophytes and ferns) that reflects knowledge about plant relationships discove ...

classification of 2016 (PPG I). Alternatively, the genus may be placed in the subfamily Thyrsopteridoideae of a more broadly defined family

Cyatheaceae The Cyatheaceae are a family of ferns, the scaly tree ferns, one of eight families in the order Cyatheales in the Pteridophyte Phylogeny Group classification of 2016 (PPG I). Alternatively, the family may defined much more broadly (Cyatheaceae ...

, the family placement used in ''

Plants of the World Online Plants of the World Online (POWO) is an online taxonomic database published by the Royal Botanic Gardens, Kew. History Following the Convention on Biological Diversity, the Royal Botanic Gardens in Kew launched Plants of the World Online i ...

'' . The oldest records of the genus are the species ''Thyrsopteris cretacea'' and ''Thyrsopteris cyathindusia'' which were described from the

Burmese amber Burmese amber, also known as Burmite or Kachin amber, is amber from the Hukawng Valley in northern Myanmar. The amber is dated to around 100 million years ago, during the latest Albian to earliest Cenomanian ages of the mid-Cretaceous period. Th ...

of Myanmar, dating to the

Cenomanian The Cenomanian is, in the International Commission on Stratigraphy's (ICS) geological timescale, the oldest or earliest age (geology), age of the Late Cretaceous epoch (geology), Epoch or the lowest stage (stratigraphy), stage of the Upper Cretace ...

of the

Cretaceous The Cretaceous ( ) is a geological period that lasted from about 143.1 to 66 mya (unit), million years ago (Mya). It is the third and final period of the Mesozoic Era (geology), Era, as well as the longest. At around 77.1 million years, it is the ...

period, around 99 million years ago. Other fossil species include ''Thyrsopteris antiqua'' from the Upper Cretaceous of Chile and ''Thyrsopteris shenii'' from the

Paleogene The Paleogene Period ( ; also spelled Palaeogene or Palæogene) is a geologic period and system that spans 43 million years from the end of the Cretaceous Period Ma (million years ago) to the beginning of the Neogene Period Ma. It is the fir ...

of King George Island, Antarctica A thyrsopterid

rachis In biology, a rachis (from the [], "backbone, spine") is a main axis or "shaft". In zoology and microbiology In vertebrates, ''rachis'' can refer to the series of articulated vertebrae, which encase the spinal cord. In this case the ''rachi ...

is also known from the Upper Cretaceous of Japan.

References

Cyatheales Monotypic fern genera Endemic flora of the Juan Fernández Islands {{Cyatheales-stub