Cryptobranchoidea

{{Short description|Suborder of salamanders}}

{{Automatic taxobox

| name = Cryptobranchoidea

| taxon = Cryptobranchoidea

| image = Cryptobranchus alleganiensis.jpg

| image_caption = Cryptobranchus alleganiensis

| image2 = Hynobius fossigenus.png

| image2_caption = Hynobius fossigenus

| fossil_range =
Middle Jurassic - Present
{{fossilrange|Bathonian|Present}}

| authority = Dunn, 1922

| subdivision_ranks = Subgroups

| subdivision = *{{extinct}}Chunerpeton?

• {{extinct}}Jeholotriton
• {{extinct}}Pangerpeton
• {{extinct}}Nesovtriton?
• {{extinct}}Iridotriton?
• {{extinct}}Kiyatriton?
• {{extinct}}Laccotriton
• {{extinct}}Sinerpeton
• Cryptobranchidae
• Panhynobia Ji, Anderson & Gao, 2021
• {{extinct}}Liaoxitriton
• {{extinct}}Linglongtriton
• {{extinct}}Neimengtriton
• {{extinct}}Regalerpeton
• {{extinct}}Nuominerpeton
• Hynobiidae

}}

The Cryptobranchoidea are a suborder of salamanders found in Asia, European Russia, and the United States. They are known as primitive salamanders, in contrast to Salamandroidea, the advanced salamanders.{{cite web|url=http://animaldiversity.ummz.umich.edu/site/accounts/information/Cryptobranchidae.html|title=ADW:Family Cryptobranchidae: giant salamanders and hellbenders|first=Heather|last=Heying}} It has two living subdivisions, Cryptobranchidae (Asian giant salamanders and hellbenders), and Hynobiidae, commonly known as Asian salamanders.

Giant salamanders are obligate paedomorphs with partial metamorphosis,{{cite journal | doi=10.1073/pnas.1703877114 | title=Evidence for complex life cycle constraints on salamander body form diversification | date=2017 | last1=Bonett | first1=Ronald M. | last2=Blair | first2=Andrea L. | journal=Proceedings of the National Academy of Sciences | volume=114 | issue=37 | pages=9936–9941 | doi-access=free | bibcode=2017PNAS..114.9936B | pmc=5604006 }} but Asiatic salamander goes through a full metamorphosis. The only known exceptions are the Longdong stream salamander, which has been documented as facultatively neotenic, and the Ezo salamander, where a now assumed extinct population from Lake Kuttarush in Hokkaido had neotenic traits like gills in adults.{{cite journal | pmc=5878659 | date=2018 | last1=Jiang | first1=J. P. | last2=Jia | first2=J. | last3=Zhang | first3=M. | last4=Gao | first4=K. Q. | title=Osteology of Batrachuperus londongensis (Urodela, Hynobiidae): Study of bony anatomy of a facultatively neotenic salamander from Mount Emei, Sichuan Province, China | journal=PeerJ | volume=6 | pages=e4517 | doi=10.7717/peerj.4517 | doi-access=free | pmid=29610705 }}

The oldest members of the group are known from the Middle Jurassic (Bathonian) aged Yanliao Biota of China.{{Cite journal|last1=Jia|first1=Jia|last2=Anderson|first2=Jason S.|last3=Gao|first3=Ke-Qin|date=2021-07-23|title=Middle Jurassic stem hynobiids from China shed light on the evolution of basal salamanders|journal=iScience|language=English|volume=24|issue=7|page=102744 |doi=10.1016/j.isci.2021.102744|pmid=34278256 |pmc=8264161 |issn=2589-0042|doi-access=free|bibcode=2021iSci...24j2744J }}