Morning Bulletin 11 Jan 1951 http://nla.gov.au/nla.news-article57065314
Leathery skin, with one large tusk protruding from its large head and a narrow tail. Not sure what this long alligator-like (but interestingly no mention of legs), creature is but it sounds interesting.
A Taniwha is a creature of Maori legend that inhabits deep, dark water, and this article notes that there has been much marine disturbance in the area that may have caused the arrival of the body on the beach.
Regardless of what it is, I would not want to encounter it if I was having an early morning swim at Waimarama beach!
Buried words and Bushwa. 
This is remarkable, I just wrote a piece about Taniwha, belief in which frustrated public building in New Zealand repeatedly. And then your mail arrived!
Cue Twilight Zone music…. I love an unexpected coincidence!