Dinosaur tail drag? Isle of Wight

[Gideon]

This cast came from just west of chilton chine on the Isle of Wight. Wealden early Cretaceous. 
 

the sandstone it comes from is found all over the beach in blocks and is riddled with foot casts of mainly iguanodons. Sauropods, crocodiles and theropods also known in this location.  
 

I have not seen anything similar to this in the area, and given the heavy dinoturbation of this particular sandstone layer I think there is a good chance this is part of a dinosaur or croc tail drag cast. 
 

I can’t see how it can be made by anything plant based or geological, but would be very interested in anyones opinion for or against my interpretation. 
 

I’ve packed it away now, but it’s roughly 10cm wide. 
 

 

[abyssunder]

Can it be a pinnidae bivalve remnant?

[Gideon]

I expect it’s too big. 10cm wide and looks like it would have been considerably longer but only have a short segment of it. Doesn’t seem to taper much. 

[Mark Kmiecik]

Striations caused by glacial transport?

[Carl]

The only way to confidently ID this as a tail drag mark would be to find it immediately in the context of a trackway. 

[Mahnmut]

Although it may not be possible to prove this as a tail trace, one could try to falsify the hypothesis and hope to fail.

I would expect a dragging trace to have really parallel groves, representing one scute or other structure each, no tapering, (although different depth of impression could explain some variation in the groove width. ) Deviations in any of the grooves should be visible in all grooves, if they represent a movement of the whole tail.

Best regards,

J

[pachy-pleuro-whatnot-odon]

I'd say that a good place to start would be to compare this with tail drag marks of other animals that may have used their tails in a similar way to dinosaurs (i.e., outstretched and for balance), although crocodiles may also be a good place to start. Find some visual material for comparison, such as the below crocodile trackways with tail drag marks from Playa Ventanas in Costa Rica, as reported by Farlow et al. (2017; figure 4 and figure 7).

 

 

 

However, while finding you the above example, I also bumped into the below image (source), which shows the exact same wide and flat-bottomed depression with parallel furrows as does your specimen, and is said to be the tail drag mark of a crocodile. The tapering mentioned above may, in that case, be due to the undulating movement of the tail, a feature that can also be made out in the below drag mark. It's still doing to be difficult to defend such a position - but so it is with many isolated foot casts as well...

 

[Gideon]

My apologies for the late reply. 
 

I don’t think glacial transport could be a possibility here. Would not have been a factor at play. However, movement of an object like a log is feasible on a floodplain frequented by flooding events. 
 

the grooves are parallel to each other with a slight curve but remaining an equal distance between each groove. The apparent slight tapering looks to be an illusion caused by the erosion on one side and matrix covering the other side. 
 

sadly there is no way to link it directly with a specific trackway. However, there was a small iggy footprint in a separate rock within 1 meter of it on the beach in the same matrix, and another within 3 meters pictured below   
 

it’s going to be a hard theory to sell! But I like the possibility. Still open to any criticism or doubt though!

 

if my back can take the strain I’ll check with the dinosaur isle museum when im

next there.