Lumpy Fossils -- What Are These?

[Boesse]

OK, I finally found the pictures in Domning's 1978 monograph on Dusisiren and other northeast Pacific hydrodamalines. It is definitely a sirenian periotic.

Unfortunately, Domning made no mention of tympanic/periotic fusion. However, the elements he illustrated are identical to these, and only labeled as periotics. Additionally, he states that the base of the promontorium/"pars cochlearis"/cochlea is a zone of weakness in sirenian periotics, due to the semicircular canals and other foramina, thus most sirenian periotics fracture in the same pattern, along this zone. So, my suspicion that the promontorium is broken away appears correct.

So, in your case Harry - I believe these are just the base of the periotic, missing the tympanic and promontorium, a condition that is apparently fairly common among sirenian periotics.

Hope this helps!

Bobby

[Harry Pristis]

OK, I finally found the pictures in Domning's 1978 monograph on Dusisiren and other northeast Pacific hydrodamalines. It is definitely a sirenian periotic.

Unfortunately, Domning made no mention of tympanic/periotic fusion. However, the elements he illustrated are identical to these, and only labeled as periotics. Additionally, he states that the base of the promontorium/"pars cochlearis"/cochlea is a zone of weakness in sirenian periotics, due to the semicircular canals and other foramina, thus most sirenian periotics fracture in the same pattern, along this zone. So, my suspicion that the promontorium is broken away appears correct.

So, in your case Harry - I believe these are just the base of the periotic, missing the tympanic and promontorium, a condition that is apparently fairly common among sirenian periotics.

Hope this helps!

Bobby

Thank you, Bobby!! Wow! These dugongs must have had substantial petrotympanics!!