السلام عليكم ورحمة الله : تحية طيبة
حياك الله أخي الاستاذ المستشار وأهلا بك في منتدى الأحياء
الخطم هو منطقة الأنف في الفك العلوي .وتتميز هذه الرتبة بوجود شكل مثلث للأعلى
يشبه المنقار (peak like ) على مقدمة الراس من ناحية الأنف ولذلك سميت خطمية
الرأس
Tuatara have skulls that are characterized by the presence of a beak like structure on the upper jaw, acrodont teeth, two complete temporal fossae,
granular scales and a mid-dorsal row of spines (Iverson 2001). Tuatara also possess a parietal eye. It is an eye concealed beneath a thin layer of scales that may play an important role in thermoregulation (Raven and Johnson 2002, Iverson 2001). Tuatara, and rhynchocephalians in general, are small bodied reptiles averaging about 60 cm. They inhabit burrows (often with petrels, shearwaters and prions). Like many reptiles tuatara exhibit temperature dependent sex determination (Cree et al 1995). They reach sexual maturity only after 15 years and take fifteen months to incubate their eggs (Mlot 1997). Tuataras are, remarkably long lived, with age records for individuals of 75 years (Mlot 1997). It is suspected that they can reach ages of 100 years or more. They are carnivores that are active at temperatures much colder than other reptiles. Their diets are rich in beetles, weta, worms, millipedes spiders and, not nearly as often, bird eggs and chicks (DOC Te Pap Atawhai 2001).
المصدر:
http://www.earlham.edu/~quinnme/tuataras_rock.htmتحياتي .....
