DiagnosisFor a very long time, this infraorder was considered to belong to the Anomura. However, recent analyses have classed the thalassinid shrimps as an infraorder in their own right. Similar to lobsters in many ways, they have a flattened abdomen with a large telson and uropods. However, their pleon is well developed and the abdominal pleura are greatly reduced.
OriginThis groups record extends back to the Early Jurassic (202 million years ago)
Images taken from www.nhm.org/guana/bvi-invt/bvi-surv/deca-inf.htm and www.google.com/images/thalassinidea.htm