Leaves and Triassic Fish

[izak_]

Recently we had a quick exploratory trip just south of Sydney in search of Triassic fish and Tertiary leaves. 

 

Our first stop yielded a terrific but partially weathered nodule exposed in an outcrop of the Ashfield Shale. A clear layer was present in the cross section so it was likely to yield a fish! 

This is it after most of it was removed, unfortunately I don't have any before photos but the layer through the middle is clearly visible:

 

Will include photos of the prep later in this post.

 

Our next stop was the main focus of our trip but wasn't too eventful unfortunately. We drove around back roads looking for new outcrops of an unnamed Tertiary formation which sometimes yields very well preserved leaves and insects. We found a few outcrops of it but only one section of road yielded any good leaves.

 

The site:

 

A freshly broken rock with leaves:

 

As soon as we got home I started on the fish nodule. The fish layer had already partially split which was helpful, but meant the inside was quite weathered and covered in calcium carbonate.

 

Splitting the nodule carefully with a knife:

 

A fresh split. Note the white calcium carbonate encrusting the surface:

 

Soaking the pieces in acetic acid (8% vinegar) to dissolve away the calcium carbonate:

 

The same piece I showed before after acid preparation, the fish are now clearly visible:

 

Splitting the rest of the nodule:

 

Reassembling after acid prep:

 

The rock is a thick siderite nodule so is very heavy once all glued together. With pieces this large I usually make a spray foam cradle for the pieces to sit in, meaning I can disassemble it to move it around. 

Loosely assembled and starting with the spray foam:

 

Surprisingly, this nodule ended up being packed with fish. The main large fish in the middle is likely a species of Elonichthys, but throughout the rest of the nodule are several other genera including Saurichthys, Cleithrolepis and Elpisopholis. Overall I can count just under 60 individual fish on this one rock, many are just small sections of scale pattern though. The Cleithrolepis is likely complete but sits underneath a couple of other fish, and the Saurichthys is tiny and incomplete but its long snout is unmistakable. The preservation in most of the specimens is poor, as with most other Ashfield Shale nodules, but the association of so many fish is of interest!

 

One half of the nodule, I haven't quite finished the counterpart yet but it does have slightly better preservation.

 

Note the partially exposed Cleithrolepis just in front of the pectoral fins of the largest fish:

 

A small but particularly densely packed section:

 

Will include more photos in coming days! 

Edited January 10 by izak_

[FranzBernhard]

6 hours ago, izak_ said:

The site:

 

A freshly broken rock with leaves:

 

This outcrop situation is very familiar to me !

Franz Bernhard

[Yoda]

@izak_

 

Some really fantastic finds. 

 

Question : How do you know exactly which plane of the nodule to split ?? 

Is there a crack forming on the exact line of the fish ?? 

[izak_]

11 minutes ago, Yoda said:

Question : How do you know exactly which plane of the nodule to split ?? 

Is there a crack forming on the exact line of the fish ??

There is indeed! This usually isn't the case for nodules from here, but there is usually still a distinctive line where the bedding plane(?) of the nodule occurs when viewed in cross section. Some nodules are devoid of fossils and there is no such line, they just look like a solid chunk of siderite. 

[RJB]

Hard to see these fish but very interesting just the same.   Suggestion, how bout a picture with an outline of the fish in one pic, and the same pic without the outline so one can go back and forth and get a better idea of where the fish are exactly?  Best of luck to ya

 

RB

[izak_]

22 minutes ago, RJB said:

Hard to see these fish but very interesting just the same.   Suggestion, how bout a picture with an outline of the fish in one pic, and the same pic without the outline so one can go back and forth and get a better idea of where the fish are exactly?  Best of luck to ya

 

RB

Sadly that's the nature of this site... will make something like that tomorrow  

[Fossildude19]

Another great report and finds, Izak!  Thanks for showing us.

 

@RJB

 

I see at least 4 fish - probably more I can't make out...

 

 

[izak_]

30 minutes ago, Fossildude19 said:

Another great report and finds, Izak!  Thanks for showing us.

Thank you!! 

 

I can't make out some of them in this photo (they are better represented on the counterpart), but here is what I can see. Keep in mind many are just small sections of faint scales, impressions or partials but do represent individual fish nonetheless. 

 

[trilobites_are_awesome]

1 hour ago, izak_ said:

Thank you!! 

 

I can't make out some of them in this photo (they are better represented on the counterpart), but here is what I can see. Keep in mind many are just small sections of faint scales, impressions or partials but do represent individual fish nonetheless. 

 

Gosh that's a lot more fish then I thought there were!

[bockryan]

Extremely impressive, what a cool find!

[Tidgy's Dad]

Very nice!

[RJB]

Very cool, thank you

 

RB

[Jaybot]

I really enjoyed this.  Thanks for sharing

[Euhoplites]

We don't see that every day, wow! Thanks for sharing

[Neanderthal Shaman]

Very cool, I'm loving all these posts from Australia as of late!