Psammosteida
| Psammosteida | |
|---|---|
 | |
| Drepanaspis gemuendenensis reconstruction | |
Scientific classification  | |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Infraphylum: | Agnatha |
| Class: | †Pteraspidomorpha |
| Subclass: | †Heterostraci |
| Order: | †Pteraspidiformes |
| Suborder: | †Psammosteida Kiaer, 1932 |
| Taxa | |
| |
Psammosteida also called as Psammosteoidei is a suborder of pteraspidid heterostracan agnathans. The psammosteids had broad, flattened bodies, suggesting a predominantly benthic habit. The earliest unequivocal psammosteid is Drepanaspis of Early Devonian Germany.[2] Other notable psammosteids include Psammosteus, and Obruchevia, two genera of enormous species with dorsal shields around one meter in diameter. The Psammosteids were the only heterostracans to survive to the end of the Devonian, where they finally perish during the Hangenberg event.
Classification
Internal relationships
Taxonomy
The following families and genera were recognised by Glinskiy (2017) in the suborder Psammosteoidei:[3]
Suborder Psammosteoidei (sensu Psammosteida Kiaer, 1932 emend. Tarlo, 1962)
- Family Drepanaspididae Traquair, 1899
- Genus Drepanaspis Schlüter, 1887
- Family Guerichosteidae Tarlo, 1964
- Genus Guerichosteus Tarlo, 1964 (= ?Hariosteus Tarlo, 1964)
- Family Obrucheviidae Tarlo, 1964
- Genus Obruchevia Whitley 1940
- Genus Perscheia Elliott, Mark-Kurik & Daeschler, 2004
- Family Русnоstеidае Tarlo, 1962
- Genus Ganosteus Rohon, 1901
- Genus Pycnolepis Tarlo, 1964
- Genus Pycnosteus Preobrazhensky, 1911
- Family Psammolepididae Tarlo, 1962
- Genus Psammolepis Agassiz, 1845
- Family Psammosteidae Traquair, 1896
- Subfamily Placosteinae Glinskiy, 2017[3]
- Genus Placosteus Agassiz, 1845
- Subfamily Psammosteinae Traquair, 1896
- Genus Elgaia Glinskiy, 2017[3]
- Genus Psammosteus Agassiz, 1844
- Genus Karelosteus Obruchev, 1933
- Genus Traquairosteus Tarlo, 1964
- Subfamily incertae sedis
- Genus Vladimirolepis Glinskiy, 2017[3]
- Subfamily Placosteinae Glinskiy, 2017[3]
- Family incertae sedis
- Genus Schizosteus Obruchev, 1940
- Genus Tartuosteus Obruchev, 1961
Phylogeny
An analysis by Glinskiy in 2017 obtained the following phylogenetic tree by strict consensus:[3]
| Psammosteoidei |
|
Drepanaspididae Guerichosteidae | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
External relationships
A 2025 comprehensive analysis on pteraspidomorph relationships by Randle et al. retained the placement of Psammosteoidei within Pteraspidiformes, with Anchipteraspididae as the deepest branching Pteraspidiformes.[1]
References
- 1 2 Randle, Emma; Keating, Joseph N.; Sansom, Robert S. (2025). "A phylogeny for Heterostraci (stem-gnathostomes)". Papers in Palaeontology. 11 (5) e70030. doi:10.1002/spp2.70030. hdl:1983/53eb7ef8-173d-42a0-9ab7-acee7506f464. ISSN 2056-2802.
- ↑ Dec, Marek (2019). "Revision of the Early Devonian psammosteids from the "Placoderm Sandstone": Implications for their body shape reconstruction" (PDF). Palaeontologia Electronica. 22 (2). doi:10.26879/948. Retrieved 2025-06-10.
- 1 2 3 4 5 Glinskiy, Vadim (2017). "Phylogenetic relationships of psammosteid heterostracans (Pteraspidiformes), Devonian jawless vertebrates". Biological Communications. 62 (4): 219–243. doi:10.21638/11701/spbu03.2017.402.