Seems a lot more plausible that it washed up on a river bank during a flood. Or it died next to a river which subsequently changed course.
> At death, he was deliberately buried in a midden initiated either shortly beforehand or contemporaneously with his burial
> The geomorphological setting and sediment properties indicate that a grave was cut into a landform positioned up to 2 m higher than the surrounding scroll plains. [..] The dingo was found in an articulated context below this surface, indicating the presence of a burial cut
>One of the Garli’s caudal vertebrae, recovered directly below the eroding burial, was sampled for AMS radiocarbon dating and returned an age range of 963–916 cal BP (ANU-75935). A freshwater mollusc shell sampled from the central burial block (UNSW-3415) returned an age of 1,178–957 cal BP. Three additional mussel fragments (cf. Velesunio sp.) were dated from Layer 1 of Zone 1 (UNSW-3414), the Garli burial core’s interface with Layer 1 (UNSW-3416), and from sediment within the burial core adjacent to the Garli skeleton itself (SANU-75235). These produced ages several hundred years younger than the Garli
Hundreds of years? Damn, that's probably well more than most cultures would afford even beloved pets.
Midden piles of fresh and saltwater shells abound in Australia - unsurprising given some 60K+ years of occupation by cruising along hunter gatherers.
The north west beaches I'm familiar with have many good fishing and marine food gathering spots and the dunes back from the high tide lines often reveal deep strata layers of shells dumped on a near daily basis over long windows of time.
Rivers are similar with remnants of fish traps (blasted by early Europeans for reasons of both navigation and moving the natives along) having waste layers (fish bones, freshwater shells, etc) nearby.
