( ( The skeleton ) ( ( is ( most ( developed ( ( ( in ( ( ( ( the arthropods ) , ) ( which ( have ( ( an ( exterior exoskeleton ) ) ( containing chitin ) ) ) ) ) , ) ) and ) ( in ( ( the vertebrates ) ( which ( have ( ( a ( sophisticated ( interior endoskeleton ) ) ) ( ( made ( of ( ( bone or ) cartilage ) ) ) ( comprising ( ( a system ) ( of ( jointed ( ( struts and ) levers ) ) ) ) ) ) ) ) ) ) ) ) ) ) ) . ) )
(ROOT (S (NP (DT The) (NN skeleton)) (VP (VBZ is) (ADJP (RBS most) (JJ developed) (PP (PP (IN in) (NP (NP (DT the) (NNS arthropods)) (, ,) (SBAR (WHNP (WDT which)) (S (VP (VBP have) (NP (NP (DT an) (NN exterior) (NN exoskeleton)) (VP (VBG containing) (NP (NN chitin))))))) (, ,))) (CC and) (PP (IN in) (NP (NP (DT the) (NNS vertebrates)) (SBAR (WHNP (WDT which)) (S (VP (VBP have) (NP (NP (DT a) (JJ sophisticated) (JJ interior) (NN endoskeleton)) (VP (VBN made) (PP (IN of) (NP (NN bone) (CC or) (NN cartilage))) (S (VP (VBG comprising) (NP (NP (DT a) (NN system)) (PP (IN of) (NP (JJ jointed) (NNS struts) (CC and) (NNS levers)))))))))))))))) (. .)))
The skeleton is most developed in the arthropods , which have an exterior exoskeleton containing chitin , and in the vertebrates which have a sophisticated interior endoskeleton made of  bone or cartilage comprising a system of jointed struts and levers.
(ROOT (S (NP (NNS Humans)) (VP (VBP possess) (NP (DT a) (PRN (-LRB- -LRB-) (NP (NN n)) (-RRB- -RRB-)) (NN endoskeleton))) (. .)))