part of part of develops_from embryonic structure lateral plate mesoderm intraembryonic coelom (...) I regard it unlikely that coeloms of all bilaterian animals are comparable and evolved very early. Considering all these questions, few convincing characters concerning the evolution of body cavities remain to be named. (...) A segmental coelom appears to have evolved at least two times, in Annelida and in Myomerata (Acrania and Craniota).[well established][VHOG] EHDAA:251 EMAPA:16088 The part of the coelom in the embryo between the somatopleuric and splanchnopleuric mesoderm; the principal body cavities of the trunk (thoracic, abdominal, and pelvic) arise from this embryonic part of the coelom UBERON:0003887 UMLS:C1512940 VHOG:0000316 consider merging with coelom. TODO - add spatial relationships to halves of LPM. Note the OG places XAO and ZFA coelem terms here. editor note: TODO check ZFA, which appears to be a structure present in adults somatic coelom uberon mesoderm-derived structure coelom