Reply on EC1: Community comment response

Discussion comment: I write ... to provide a few short comments on the paper by Amoo et al. on Late Eocene to Early Oligocene vegetation of the Tasmanian Gateway Region in the hope that it may improve their paper, but also set some ground rules for future authors from the Northern Hemisphere who wish to work on pollen records from this paret of the Southern Hemishpere. My name is Ian Sluiter, and I am happy for you to provide the comments to the authors with my name known. I have been working on, and will publish very soon, a terrestrial pollen record from Gippsland (Victoria) which lies ~730km to the NNW of ODP1172. That is ~5.5degrees latitude north. The general thrust of a warming episode at our site mirrors the changes recorded by Amoo et al., but I am not exactly sure how this has come about.


(Strasbergeria), Ulmaceae and even small Proteaceae would be washed down the sink!
Response: Sieving marine palynological samples is a standard technique and is required to remove unwanted organic/inorganic matter, and to increase the pollen concentration which is much lower in marine sediments than in terrestrial peat samples. Like Contreras et al. (2014), who covered the Early Eocene vegetation record of site 1172, our Eocene-Oligocene study reanalysed slides from the same batch of samples that were originally processed for marine palynology at the Laboratory of Palaeobotany and Palynology of Utrecht University. We systematically compared samples sieved at 15 and 10 µm from the adjacent site ODP 1168 (western Tasmanian margin, Amoo et al. in prep) and ODP site 696 (Drake Passage; Thompson et al., 2021) and found no differences. Small pollen grains from e.g., Myrtaceidites and Cupanieidites are present in small quantities (<1-2%) in all batches.
Unfortunately, the author of the discussion comment provides no reference for his estimate of up to 70% loss of pollen grains due to sieving, but we can certainly exclude such a loss in our labs, as we also regularly control the sieving residues. However, we agree that sieving (like many other lab procedures which are unfortunately necessary) potentially increases the risk of losing small pollen grains. Following their comments, we will add respective remarks to our method section.

Discussion comment: This is a very serious loss of data and necessarily simplifies any vegetation reconstructions. Moreover, the use of diversity indices like S-W and Evenness become redundant.
Response: We do not have any evidence for a "loss of data". How vegetation is reflected in a pollen record is strongly influenced by the location, depositional environment, and sedimentology. In this regard, a pollen record from a marine core provides indeed a "simplified" picture of the terrestrial vegetation if compared to a terrestrial peat bog record which archives the full diversity of the local swamp vegetation. Regardless of the geological time or continent, particular caution should be exercise when comparing biodiversity from pollen records from different depositional environments. We therefore use the index to record relative changes at this ODP site only. In response to concerns raised in the discussion comments, we will make this restriction clearer in our method section and explain the particular limitations of marine pollen records.
Discussion comment: This is a marine pollen record from 250km ESE of Tasmania. A Lat/Long at Line 64 would be appreciated.

Response:
The coordinates of Site 1172 are already provided in chapter 2.1 (line 83) which includes the site description. In case of a misunderstanding, we slightly reworded this part to make it clearer that these coordinates refer to the coring site, and not to the East Tasman Plateau. We could not find any reference for the estimate of 250 km, and we therefore keep our estimate of ~170 km southeast of Tasmania with reference to the 1172 Shipboard Scientific Party (2001).

Discussion comment: The record seriously over-records the importance of Pteridophytes, at least when compared with terrestrial records from Tasmania and Gippsland.
Response: We do not understand why our sporomorph record "seriously over-records Pteridophytes". The late Eocene total spores at site 1172 on average accounts for about 11% of all non-reworked sporomorphs, and this resembles the spore percentage abundance trend of the terrestrial T1 Coal Seam (late Eocene/Middle N. asperus Zone) records from the Gippsland Basin and Otway Basin in southern Australia (Holdgate et al., 2017).

Discussion comment:
The vegetation descriptions about Tasmanian vegetation at the time lack substance. I have never seen an Australian Tertiary record without Myrtaceae! I presume they must have been washed down the sink which makes the description a whole lot easier, I guess! Response: Mrytaceae (i.e., Myrtaceidites) and Dacrycarpus (i.e., Dacrycarpites) also occur in the pollen record of Site 1172. We think there might be a misunderstanding. The pollen diagram (Fig. 2) does include selected taxa only, as indicated in the figure caption. A full list of all taxa (raw dataset) including those occurring with percentages <1% can be found at https://doi.org/10.5281/zenodo.5924930. Here we followed Climate of the Past publication guidelines and uploaded the raw count dataset onto an appropriate data repository.

Discussion comment: This is an Australian -Not New Zealand Tertiary Record
Most of the pollen ID's seem to be aligned with NZ Tertiary taxa, and not with Australian pollen taxa. It is easy to quote Ian Raine I guess, as Australia do not have a compendium like NZ has. But to do so comes with some basic flaws and oversights.
Response: Raine et al. (2011) is to date the most complete and detailed illustrated pollen and spore catalogue available for pre-Quaternary studies of the southern high latitudes. We therefore prefer to stay with this catalogue as the first reference. We are certainly happy to adapt the Australian nomenclature if this helps to improve our reconstruction (see response below regarding Nothofagidites nomenclature).

Response:
We identified clear morphological differences between the N. matauraensis, N. cranwelliae and N. emarcidus taxa. Morphologically, N. cranwelliae and N. emarcidus complex do have the same slightly concave to straight sides, however, whiles spines on N. cranwelliae decrease in density from poles toward the equator, N. emarcidus has these spines evenly distributed across the grain (Dettmann et al., 1990;Prebble, 2016). N. matauraensis can mostly be distinguished from N. cranwelliae and N. emarcidus by its characteristic pentagonal shape.
To simplify our taxonomy and make it easily relatable to Australian taxonomy, we followed the author of this discussion comment suggestion and combined N. emarcidus, N. cranwelliae and N. matauraensis into the Nothofagidites emarcidus complex. For Nothofagidites lachlaniae, we respectfully disagree that this taxon is more aligned to New Zealand pollen types as previous studies have also found them in Australia (e.g., Pole, 2001). However, to address the concerns raised, we modify the N. lachlaniae to Nothofagidites lachlaniae complex to make it more comparable to a previously published Paleocene to Eocene record of Contreras et al. (2014) from Site 1172.
With respect to Nothofagidites flemingii, we are reluctant to add it to the modern subgenus Nothofagus. As this is a Paleogene record, we prefer to use the conventional nomenclature and keep taxonomic distinction between modern plants and the fossil palynomorphs. Also, we mentioned in our manuscript (lines 260-261) that we categorised our Nothofagidites pollen taxa into Brassospora, Lophozonia, and Fuscospora following Dettmann et al. (1990). We therefore would like to keep our categorisation this way as Fusca Type B is considered Fuscospora according to Dettmann et al. (1990).
It is however important to note that, the above-described taxonomic revisions do not affect the vegetation and climate interpretations.

Discussion comment: A comment on Phyllocladidites mawsonii. This pollen taxon hits some pretty big numbers further north in Gippsland at the same time. I am seriously curious as to its relatively low representation at ODP1172, especially given the loss of the smalls down the sink. Perhaps it is due to over-representation from the spores.
Response: Based on our records from Site 1172, Phyllocladidites mawsonii represents one of the common pollen taxa as we mentioned in Section 4 (lines 237-238) of our manuscript, and in some instances making up to 17% of our non-reworked sporomorphs. The differences in representation of Phyllocladidites mawsonii may be site specific, and most likely independent of relative percentages of Cryptogams. This is further supported by representation of Phyllocladidites from previously published Eocene records in Site 1172 (Contreras et al., 2014) being comparable to those presented in our records. Nevertheless, it is apparent that Phyllocladidites mawsonii may have been overrepresented in terrestrial Gippsland Basin records as compared to same taxon recovered from the Middle Nothofagidites asperus Zone in the Groper-1, Mullet-1 and Bluebone-1 wells, offshore Gippsland Basin, southeast Australia (Partridge, 2006b). Coincidentally, the percentage abundance of Phyllocladidites mawsonii presented from our marine pollen record on the ETP (ODP Site 1172) is comparable to those recovered offshore Gippsland Basin. We will add this information to our revised manuscript.
Discussion comment: What is Spinizonocolpites sp.? This genus ?Nypa is well gone (extinct) by the Late Eocene from southeastern Australia. No evidence is forthcoming for it at the same time in Gippsland further to the north. Can the authors be absolutely sure that this is not Early Eocene re-working?
Response: Our Spinizonocolpites pollen grain is significantly smaller than 30 microns and we therefore preferred to call this Spinizonocolpites sp. (Spinizonocolpites-type; Martínez et al., 2016) with Arecaceae being the nearest living relative (NLR), rather than calling it Spinizonocolpites prominatus with Nypa fruticans being the NLR. However, according to Macphail et al., (1994), the middle Eocene extinction of Nypa in the Gippsland Basin are considered to be mostly local and not representative of a region-wide event. Region-wide extinction of megathermal taxa such as Nypa fruticans and Cupanieae are reported to have occurred in the late Eocene and they never crossed into the early Oligocene (Read et al., 1990;Macphail. et al., 1994). These are consistent with our pollen record as our Spinizonocolpites sp. pollen do not cross into the Oligocene. The taxon also occurs together with other warm loving taxa throughout the Late Eocene, providing further support for a synsedimentary deposition. For further clarification, we will add these comments to the revised manuscript.

Discussion comment:
I also question what the entity/identity of Malvacearumpollis mannanensis might be?