5 letters:
boris, doris, dorus, foris, goris, horus, joris, korus, lores, loris, lorus, moris, morus, noris, orris, porus, soris, sorus, toris, torus, voris, zoris

6 letters:
acorus, boris', borris, chorus, cloris, dorice, dorris, floris, florus, forres, for us, horace, kauris, laurus, maurus, morice, morris, norice, norris, orrice, porous, saurus, sorice, sporus, taurus, torose, torras, tsoris, turris

7 letters:
-saurus, chloris, delores, dolores, doloris, laurice, lycoris, morrice, morris', morriss, nourice, ptloris, pylorus, sporous

8 letters:
botaurus, chlorous, clitoris, clitorus, diodorus, eosaurus, mcmorris, metaurus, nourrice, petaurus, prioress, sartoris

9 letters:
adasaurus, authorise, before us, corchorus, epidaurus, in chorus, liquorice, mantorras, montgoris, mussaurus, polyborus, polydorus, polyporus, prochorus, rectoress, sepphoris, squarrous, thesaurus, tortorice, urosaurus

10 letters:
allosaurus, atlasaurus, aucasaurus, barosaurus, bos taurus, centauress, cyclosorus, dakosaurus, dinosaurus, dryosaurus, fitzmorris, gasosaurus, gorosaurus, heliodorus, laetiporus, lotosaurus, mapusaurus, mauisaurus, megasaurus, mesosaurus, minotaurus, mixosaurus, morosaurus, mosasaurus, mososaurus, nanosaurus, nigroporus, nodosaurus, oligoporus, ophisaurus, pliosaurus, poposaurus, rajasaurus, restore us, sceloporus, semichorus, silesaurus, sinosaurus, slow loris, torosaurus, tylosaurus, uredosorus, xenosaurus

11 letters:
alamosaurus, amurosaurus, anteosaurus, apatosaurus, archosaurus, artemidorus, athenodorus, bulbasaurus, camptosorus, carnotaurus, cassiodorus, cetiosaurus, cistothorus, dean norris, dipsosaurus, einiosaurus, fitzmaurice, genus loris, gorgosaurus, hadrosaurus, hydrosaurus, icarosaurus, isanosaurus, kamuysaurus, kritosaurus, kronosaurus, limaysaurus, luchasaurus, lurdusaurus, nanuqsaurus, nigersaurus, nothosaurus, nyasasaurus, nyctosaurus, ophiotaurus, paleosaurus, philochorus, phylloporus, pleiosaurus, pleurosorus, pseudacorus, purussaurus, saltasaurus, sarahsaurus, sarcosaurus, scutosaurus, segnosaurus, shunosaurus, siamosaurus, spinosaurus, stegosaurus, stesichorus, suchosaurus, supersaurus, tarbosaurus, teleosaurus, three-torus, thryothorus, torvosaurus, turiasaurus, ultrasaurus

12 letters:
amargasaurus, ampelosaurus, ankylosaurus, bajadasaurus, basilosaurus, brontosaurus, camarasaurus, camptosaurus, centrosaurus, ceratosaurus, chasmosaurus, chindesaurus, chuck norris, denversaurus, dryptosaurus, dyoplosaurus, edaphosaurus, elasmosaurus, erlikosaurus, eunotosaurus, europasaurus, eye of horus, futabasaurus, gojirasaurus, greek chorus, hydrochoerus, hylaeosaurus, kentrosaurus, lambeosaurus, lando norris, lystrosaurus, maquiladoras, megalosaurus, ouranosaurus, parksosaurus, pinacosaurus, pisanosaurus, plateosaurus, plesiosaurus, puertasaurus, qantassaurus, rapetosaurus, seismosaurus, shastasaurus, sonorasaurus, stellasaurus, teratosaurus, tetragonurus, titanosaurus, vespersaurus, wuerhosaurus

13 letters:
achelousaurus, albertosaurus, alectrosaurus, arizonasaurus, bahariasaurus, brachiosaurus, cadborosaurus, champsosaurus, charonosaurus, chrysochloris, corythosaurus, cyclotosaurus, daemonosaurus, dicraeosaurus, dilophosaurus, dolichosaurus, dromaeosaurus, edmontosaurus, elaphrosaurus, genus chloris, gigantosaurus, herrerasaurus, ichthyosaurus, lesothosaurus, lufengosaurus, magyarosaurus, majungasaurus, nipponosaurus, panoplosaurus, proterosaurus, savannasaurus, scelidosaurus, scomberomorus, shringasaurus, slender loris, styracosaurus, tenontosaurus, trematosaurus, tyrannosaurus, zephyrosaurus

14 letters:
anodontosaurus, chlamydosaurus, crichtonsaurus, cristatusaurus, daspletosaurus, doch-an-dorris, eromangasaurus, giganotosaurus, huayangosaurus, incisivosaurus, mastodonsaurus, psittacosaurus, qianzhousaurus, scutellosaurus, staurikosaurus, thescelosaurus

15 letters:
argentinosaurus, camarillasaurus, cryolophosaurus, metridiochoerus, monolophosaurus, ophthalmosaurus, petrolacosaurus, proceratosaurus, pycnonemosaurus, shantungosaurus, therizinosaurus, tuojiangosaurus

16 letters:
acrocanthosaurus, appalachiosaurus, ekrixinatosaurus, futalognkosaurus, muttaburrasaurus, pachyrhinosaurus, sigilmassasaurus, sinornithosaurus, stenonychosaurus, temnodontosaurus, thecodontosaurus, yangchuanosaurus

17 letters:
bruhathkayosaurus, genus stegosaurus, gigantspinosaurus, haplocanthosaurus, heterodontosaurus

18 letters:
genus brontosaurus, metriacanthosaurus, pachycephalosaurus

19 letters:
carcharodontosaurus, genus tyrannosaurus

23 letters:
micropachycephalosaurus

4 letters:
iris

5 letters:
siris, xyris, naris, paris

6 letters:
harris, derris, merits, osiris, burris, ferris, gerris

7 letters:
spirits, maurice, myrrhis

8 letters:
theorise, phalaris

9 letters:
elaphurus, psephurus, trachurus

10 letters:
herb paris, acanthurus, pomaderris

11 letters:
agriocharis, genus paris, hypochaeris, tetraneuris

13 letters:
chamaecyparis

16 letters:
plaster of paris