Getting the hang of the jargon. Plesiomorphic is a primitive characteristic. Here are some notable differences:
- The caudal cervical and 10 thoracic vertebrae of Gansus are plesiomorphically not heterocoelous.
- The strutlike, plesiomorphically apneumatic coracoid possesses well-developed procoracoid and lateral processes (Fig. 2E and fig. S2), a deep circular scapular cotyle, and a humeral articular facet situated well ventral to the acrocoracoid process.
- The proximal end of the plesiomorphically apneumatic humerus exhibits a ventral tubercle, capital incisure, and domed articular condyle.
- A tibiotarsal extensor canal is present as an emarginate groove that plesiomorphically lacks a supratendinal pons.
Hai-lu You, Matthew C. Lamanna, Jerald D. Harris, Luis M. Chiappe, Jingmai O'Connor, Shu-an Ji, Jun-chang Lü, Chong-xi Yuan, Da-qing Li, Xing Zhang, Kenneth J. Lacovara, Peter Dodson, Qiang Ji. "A Nearly Modern Amphibious Bird from the Early Cretaceous of Northwestern China."
Science.
2006,
312, 1640-1643.
Getting the hang of the jargon. Plesiomorphic is a primitive characteristic...I get it, use the word "plesiomorphic" when describing the features of allegedly gabillion-year-old specimens.
I wonder if the 11 million year old "extinct" Laotian rock rat, recently found in a meat market and other places, has any "plesiomorphic" features.