Using historical research to constrain the provenance and age of the first recorded collection of extinct Pleistocene large mammal fossils from the Naracoorte Caves, South Australia

ABSTRACT Fossil collections housed in museums are a rich source of data for palaeontologists; however, some early collections lack detailed contextual information. The Naracoorte Caves in South Australia contain World Heritage listed Quaternary vertebrate fossil accumulations, particularly those of large, extinct mammals. The first recorded collection of extinct Pleistocene large mammal fossils from Naracoorte was from Specimen Cave in 1908. Unfortunately, these fossils were collected without stratigraphic and contextual information and so lack the detail required to relate them and their provenance to new excavations in the cave. As a result, the scientific value of this fossil collection is greatly reduced. Here we report on our research into the history of fossil collecting in Specimen Cave and recover information on the stratigraphic provenance and age of the 1908 fossil collection. We analysed newspaper articles, reports, written correspondence and cave inscriptions. Our research confirmed that the 1908 collection originated from the same area as the modern excavation and revealed a history of exploration and excavation work within the cave. Our research also led to the discovery of a cave inscription that contains the name of William Reddan, an important historical figure of the Naracoorte Caves and the first person to report the Specimen Cave fossil material. These findings place the 1908 fossil collection within the current geochronological context for the site and greatly increase the scientific value of this important material.


Introduction
While many palaeontological studies report on newly excavated fossil material, others focus on existing collections held in museums or similar institutions. Some of these collections, particularly those from the 19 th and early 20 th centuries, were collected at a time when less attention was given to recording precise contextual data than is expected from more recent fossil collections. Without these data, limited information can be gleaned about the fossil site, and the scientific utility of such collections may be thereby limited (Bestwick & Smith, 2015;Reed et al., 2019;Fara et al., 2005). This is particularly so when trying to reconstruct fossil site depositional histories, as the taphonomic and geochronological context of the fossils rely on having accurate contextual and stratigraphic data. A commonly used method for overcoming this obstacle involves research into the history of the fossil sites in question, using "clues" left behind in fossil collections and historical documents (e.g. Archer et al., 1980;Bestwick & Smith, 2015;Dawson, 1985;Louys & Price, 2015;Rosenberg & Khoo, 2018;Tanke, 2005). This historical "detective work" can elucidate critical details for researchers aiming to integrate fossil collections with poor contextual data into modern studies of fossil sites.
Here we report on historical research related to Specimen Cave, part of the globally significant Naracoorte cave complex in South Australia. In 1908, the first known excavation of extinct Pleistocene large mammal fossils from Naracoorte Caves occurred in this cave. A large amount of fossil material was deposited in the South Australian Museum (SAM); however, most of this material has since remained unstudied and lacks contextual data that could be used to determine its association with the site of recent excavations undertaken by the authors. Our aim for this study was to piece together the history of palaeontological collections within Specimen Cave using historical documents and careful examination of the cave. In doing so, we aimed to gather much needed locality data for the 1908 collection and successfully place these fossils in the current geochronological context for the site. A further aim was to contribute to the growing body of information on the early history of fossil collecting at Naracoorte.

The Naracoorte Caves
The Naracoorte region of South Australia contains hundreds of limestone caves, many of which contain well-preserved Quaternary vertebrate fossil deposits (Reed & Bourne, 2000;Reed, 2021). The largest and most extensive of these caves are located within the Naracoorte Caves World Heritage Area, which is part of the Australian Fossil Mammal Sites (Riversleigh/Naracoorte) World Heritage property. This property is a serial listing shared with the Riversleigh World Heritage Site in north-western Queensland, Australia (Reed, 2021). Outside of the park boundaries, several other cave sites have palaeontological value (Reed & Bourne, 2000). The Naracoorte caves formed at least 1.34 million years ago within the Miocene Naracoorte member of the Gambier Limestone via phreatic solution and structural influences related to the underlying Kanawinka Fault White & Webb, 2015). The vertebrate fossil deposits within the caves range in age from approximately ca. 520,000 years old (Prideaux et al., 2007), to less than 1,000 years old (Atkins et al., 2022), making the Naracoorte Caves one of few fossil localities in the world to preserve a near-complete record of the last half million years.
The first report of vertebrate fossils from the Naracoorte Caves was made in 1858 by Reverend Julian Edmund Tenison-Woods, who described a collection of small mammal bones from Blanche Cave (Reed & Bourne, 2013;Woods, 1858). Extinct Pleistocene large animal species were not reported until the early 20 th century, following the discovery of fossil bones in Specimen Cave and Alexandra Cave by the caretaker of the caves, William Reddan (Reed, 2019;Pledge, 1977). Reddan was an important figure in the history of the Naracoorte Caves. In 1886, he was appointed Caretaker of the Cave Range Forest Reserve, a position he held until 1919 (Hamilton-Smith, 2006). In this role, Reddan discovered several caves in the region, including Victoria Fossil Cave in 1894 (Wells et al., 1979) and Alexandra Cave in 1908 (Curry et al., 2014).
The vertebrate fossils collected from Specimen Cave in 1908 are registered in the SAM Palaeontology Collection. William Redden sent a small number of fossils to the museum for identification in July 1908. He had inscribed the bones with the locality and date of collection ( Figure 1). A more extensive collection was made later in the year by the museum Director's assistant Friedrich Zietz, who visited the cave with the Director Dr Edward Stirling, and stayed for several days to collect bones ("Searching for fossil bones of an extinct animal at the caves", 1908). This collection is accompanied by labels which clearly state Specimen Cave as the collection site ( Figure 1); however, the exact location within the cave remains unknown. Reddan and Zietz's combined collection contains over 1000 large animal bones, representing extant and extinct macropods (Macropus giganteus Shaw, 1790 /fuliginosus (Macropus giganteus Shaw, 1790 /fuliginosus (Desmarest, 1817), Notamacropus rufogriseus (Desmarest, 1817), Protemnodon sp. cf. P. brehus (Owen, 1874), Simosthenurus (Tedford, 1966) spp.), marsupial predators (Thylacoleo carnifex Owen, 1859, Thylacinus cynocephalus (Harris, 1808), Sarcophilus laniarius (Owen, 1838)), diprotodontids, and Emu (Dromaius novaehollandiae (Latham, 1790)). The collection also contains large numbers of small animal bones, some of which represent rodent species. The remaining small animal bones from the 1908 collection are yet to be identified.

Study site -Specimen Cave
Specimen Cave, also known as Zietz Cave, (Australian Speleological Reference number 5U35) is located on private property bordering the Naracoorte Caves World Heritage Area ( Figure 2). Access to the cave is via a 2 m deep solution pipe entrance that opens to a single large chamber approximately 50 m long and approximately 15 m wide. There is a human-made hole in the flowstone floor of the cave in the north-east corner of the main chamber ( Figure 3). While the anthropogenic origin of the hole is clear, its history is unknown, including the date it was created, the people involved, and the reason for its creation. The hole exposed a well-stratified sediment deposit below the flowstone, containing fossil bones. In 2018, we excavated a shallow 1 m 2 pit in this deposit revealing a diverse vertebrate faunal assemblage that was interpreted to have been accumulated via a pitfall trap (Turner, 2018). This sediment deposit is the likely source for the 1908 SAM collection; however, this is not confirmed in any existing records or publications.

Methods
We undertook an extensive literature search for historical documents related to Specimen Cave, including newspaper articles, museum reports and correspondence. Key information sources for our review were the online databases of the National Library of Australia (TROVE), the South Australian Museum archives, university library collections, and the State Records of South Australia. Additional information was sourced from the labels associated with the Specimen Cave fossil collection housed in the Palaeontology collections of the South Australian Museum. In 1908, William Reddan wrote a letter regarding his discovery of bones in Specimen Cave, which we viewed at the State Records of South Australia and subsequently transcribed (Appendix 1; Supplemental material 1). This letter appears to be the third piece of communication in a series of correspondence between Reddan and Stirling. The first piece of correspondence appears to have been sent by Reddan and provided information on his collection of bones from Specimen Cave. The second letter appears to have been sent by Stirling, asking for further clarification. Despite extensive searching, these earlier letters could not be located.
In addition to the literature review, we visited Specimen Cave several times between 2018 and 2022 to scope out excavation sites and search for evidence of historical cave writing on walls and speleothems. Our search for cave writing focussed mainly on calcite columns, based on our prior observations of cave writing on these structures in other caves in the region. Significant pieces of writing were photographed and, where possible, interpreted on site. Digital copies of the cave writings were created by tracing the photographs with an Apple Pencil®, iPad® and the program Procreate®.

Early history of Specimen Cave
Naracoorte is the Land of the Traditional Owners and Custodians of the area, namely the Meintangk, Jardwadjali, Potaruwutij and Boandik Peoples (Reed, 2021;Tindale, 1940Tindale, , 1974. Despite their strong cultural connection to the area, there is no physical evidence that Aboriginal Peoples used Specimen Cave prior to European colonisation. European colonisers started visiting Specimen Cave somewhere between the mid-1840s, when the Naracoorte region was settled (Lewis, 1977), and 1869 when the cave was first referenced in print. An article in The South Australian Advertiser reported on the South Australian Governor's tour to the region and described an "exploring expedition" to Specimen Cave.
The majority of those present afterwards undertook a short exploring expedition to the "Specimen Cave", a chamber distinguished for its numerous stalactites, which, alas, were sadly mutilated, evidencing, as His Excellency remarked, the proneness of the Anglo-Saxon temperament to destroy and mutilate ("east, 1869, p. 1) Specimen Cave is referenced in other newspaper articles throughout the remainder of the 19th century, suggesting it was a popular destination for both locals and tourists. The following is an extract from a guide to the Naracoorte Caves, published in the Australian Town and Country Journal in 1895.
The last two caves to be visited are the "Sixty-foot Cave", [Cathedral Cave] and the "Specimen Cave". . . . the latter cave is also entered by a ladder. These caves, although perhaps not so extensive as the others [e.g., Blanche Cave, Bat Cave], abound in natural beauty, and go to make up a museum of natural wonders ("The Narracoorte Caves, 1895, p. 31) In addition to providing historical information about Specimen Cave, these articles provide an important point of reference for investigating the origin and timing of anthropogenic damage inflicted upon the cave. Today, Specimen Cave contains very few intact speleothems. A significant amount of this damage probably occurred shortly after people started visiting the cave, as evidenced by comments in local newspapers ("east, 1869). Other anthropogenic impacts on the cave include extensive "graffiti" and soot from candle smoke and magnesium lights, some of which were undoubtedly inflicted during visits to the cave in the 19 th century.

Discovery of Pleistocene fossils
Although Specimen Cave was visited extensively during the 19 th century, it did not receive scientific attention until the early 1900s. In 1908, while undertaking unspecified work within Specimen Cave, the caretaker of the Caves, William Reddan, discovered several large fossilised cranial elements. Following this discovery, Reddan collected the cranial remains, along with a small sample of post-cranial bones, and sent them to the Adelaide Museum (now known as the South Australian Museum) (Figure 1). At the museum, the bones were examined by the museum's director Dr Edward Stirling ("Searching for fossil bones of an extinct animal at the caves", 1908). Reddan described the discovery of the bones in a letter to Stirling (Appendix 1; Supplemental material 1).
The place where the bones were found has been but very little disturbed. The deposit is in what is known as the "Specimen Cave", one of the old set of caves. between [stricken] -the last of them in a southerly direction & west of the plantation on the road to the Victoria Cave (Reddan, 1908).
Stirling identified the cranial fossils as the extinct "marsupial lion" Thylacoleo carnifex (see Stirling, 1908). This discovery was significant as it was the first reported specimen of T. carnifex from Naracoorte (Curry et al., 2014), and the first report of fossils belonging to extinct Pleistocene large mammals at Naracoorte Caves (Reed & Bourne, 2000). Stirling mentioned the Specimen Cave fossils collected by Reddan in a report to the Board of Governors of the Public Library, Museum, and Art Gallery of South Australia.
A further collection of fossil bones has, by the courtesy of the Woods and Forest Department, been received from the "Specimen" Cave, Naracoorte. This contains some undoubted remains of the so-called marsupial lion (Thylacoleo), and may perhaps on further study be found to contain also the bones of this little known animal that have not yet been discovered. Both these deposits [Specimen Cave and a deposit on Kangaroo Island] are well worthy of further investigation on the spot, and it is intended that this shall be done. (Stirling, 1908, p. 8).
After receiving the sample of fossils sent by Reddan, Stirling travelled to Naracoorte in December 1908 with his assistant Friedrich Zietz to collect more fossils from Specimen Cave. He may have been motivated to collect more bones of T. carnifex ("Searching for fossil bones of an extinct animal at the caves", 1908), which at this time was primarily known from cranial elements (Curry et al., 2014;Daily, 1960 . Stirling and Zietz collected a large sample of bones which they took to the Adelaide Museum ("Searching for fossil bones of an extinct animal at the caves", 1908). Much of this material consists of post-cranial elements, with particularly large numbers of macropod bones. The sample also contains smaller numbers of cranial elements, including those of T. carnifex (Figure 1). Despite Stirling's apparent interest in the fossil material and his intentions to continue investigations, no additional collections were made in the first half of the 20th century and most of Reddan's, Stirling's, and Zietz's fossil samples remained stored in boxes and not studied in detail until our recent investigation.

Locality data for 1908 fossil collections
The fossils collected by Reddan, Stirling and Zietz in 1908 lack detailed locality and stratigraphic data, with only the name of the cave included in the accompanying labels. As a result, the exact location of the collection site within the cave has remained unclear. A letter sent by Reddan to Stirling in 1908(Reddan, 1908; Appendix 1; Supplemental material 1), contains important information regarding the source of the fossils.
There may be many passages or water channels leading out of this cave, I started to clear the one which looked the largest & easiest worked going in a S.E. direction. All the passages are filled completely with drift. A hole was chased out about 5 feet deep in front of the passage just mentioned for convenience of working. About a foot from the surface at this spot the bones were found . . . Bones were found here & there as far as the men went & were seen in the roof of a little chamber protruding between stones high above the floor (Reddan, 1908) The passage that was "chased out" by Reddan and his team is visible in the north-east corner of the cave, adjacent to our new excavation pit and below the large hole in the overlying flowstone (Figures 3 and 4). Reddan's letter confirms that this hole was anthropogenic in origin, and that he and his team of workers created it in 1908 for "convenience of working" (Reddan, 1908). The letter also provides locality information for the 1908 fossil collection. In his letter, Reddan reveals that he found the bones "about a foot from the surface" (beneath the capping flowstone) at the site where he created the hole (Reddan, 1908). This location is in very close proximity to the modern excavation pit (Figures 3 and 4). Reddan also mentions discovering bones in the "roof of a little chamber protruding between stones high above the floor" (Reddan, 1908). This chamber is probably the same small chamber that we visited in 2018 and recorded bones when we scoped out the site for our excavation.
The two locations that we collected bones from in 2018 are the only places in the cave where large fossils have been discovered. This further supports the conclusion that Reddan collected from these locations. There can be little doubt that the fossils collected by Stirling and Zietz in 1908 originated from the same location as the fossils collected by Reddan and the previously removed upper sediment layers of our new excavation site.
In his letter to Stirling, Reddan (1908) also mentioned several other caves in the Naracoorte region, including Big Cave (a.k.a. Blanche Cave), Bat Cave, Victoria Cave (a. k.a. Victoria Fossil Cave) and a "new cave", which we believe to be Alexandra Cave. Reddan also noted the presence of small animal fossils within these caves and a Thylacoleo carnifex tooth within the "new cave". Reddan also described the sediment in some of these caves, namely Bat Cave and Alexandra Cave (Reddan, 1908).

th century cave writing
Specimen Cave contains a significant amount of writing both on the cave walls and on speleothems. The writing on the walls is either engraved or made with candle smoke, and consists of single names, initials, letters and illegible words or marks. The writing appears to date from early European colonisation to the late 20 th  Arnold et al. (2022) and Priya et al. (2022), and summarised in the text. Photo: S. Bourne. Century but has not previously been reported as historically significant. Our search of the cave revealed an inscription located on a calcite column at the north-east corner of the main chamber of the cave, adjacent to the fossil excavation site ( Figure 5). The text, written in graphite pencil, contains a list of five names (M. Fogarty, W. Long, F. Drake, E. McLauhlin and F. Green), followed by the text "tree planters for the year 1890". The text also contains the name "W. Reddan", followed by "Commander in Chief", which undoubtedly refers to William Reddan. As far as we are aware, this is the first discovery of cave writing in the Naracoorte region that contains Reddan's name. The date of the inscription (1890) indicates that Reddan visited the cave at least 18 years before he discovered the Thylacoleo carnifex remains. The location of the inscribed column also indicates that Reddan came very close to the fossil deposit as early as 1890. The choice to inscribe that particular column, instead of another one of the numerous columns in Specimen Cave, may also indicate that Reddan was particularly interested in that area of the cave. (Figure 5).
It is unclear whether the 1890 writing was created by Reddan himself, or by another one of the "tree planters" named in the inscription. Some elements of the cave inscription, such as the capitalised cursive letter "C", bear some resemblance to Reddan's handwriting in his 1908 letter. Other elements, such as the capital letter "T", do not resemble Reddan's handwriting ( Figure 5; Supplemental material 1). Comparing these two handwriting elements is difficult and potentially problematic, as they were produced 18 years apart, on different materials (paper and calcite) and with different instruments (pen and ink and graphite). Additionally, most of the cave inscription is written in capitalised block script while the letter is written in cursive sentence script. For these reasons, we could not confidently conclude that Reddan wrote the inscription.
The newly discovered writing in Specimen Cave joins a growing list of important 19th and 20th century writings and drawings in Australian caves (Reed & Bourne, 2018;Whyte, 1997). Its presence clearly demonstrates the value of historical cave writing and the positive contributions it can make to both palaeontological and historical investigations. It also demonstrates the importance of preserving, rather than removing, cave writing. Not only does removing cave writing inhibit future study and research, but it also has the potential to damage cave walls and sensitive cave environments (Reed & Bourne, 2018).

Specimen Cave in the late 20 th and 21 st centuries
Following Stirling and Zietz's investigation in 1908, Specimen Cave received little additional scientific attention in the first half of the 20th century. Over 60 individual cranial fossils recovered in 1908 have been identified and are registered in the Palaeontology Collection of the South Australian Museum's Palaeontology Collection (Reed & Bourne, 2000;Turner, 2018). The cave was surveyed and mapped in 1959 by P. Aitken, J. Peters, and R. Sexton from the Cave Exploration Group of South Australia (Figure 3). Maddock (1971) reported on his collection of recent, sub-fossil bones from the surface of the cave floor near the entrance. As these bones did not originate from the fossil deposit, they do not shed light on the Pleistocene palaeontology of the cave. Details on the Pleistocene palaeontology of Specimen Cave appeared in two other publications prior to 2018, both of which contain faunal lists for various fossil deposits in the region (Reed & Bourne, 2000;Williams, 1980). In 2018, we undertook a preliminary palaeontological investigation of the Specimen Cave fossil deposit, which included the first systematic excavation within the cave (Turner, 2018).
Recent geochronological research has clarified the age of the upper units of the fossil deposit and the overlying flowstone Mahlknecht, 2018;Priya et al., 2022;Weij et al., 2022). The U-Th dating of the flowstone yielded ages of 145.0 ± 3.5 (2σ) ka and 142.8 ± 2.1 (2σ) ka (weighted mean = 143.9 ± 2.8 (2σ) ka; see Weij et al., 2022). Single-grain optically stimulated luminescence, single-grain thermally transferred optically stimulated luminescence and electron spin resonance (Ti-H centre) dating of the fossiliferous sediments 85 cm below the flowstone surface yielded ages of 134.7 ± 8.7 (1σ) ka to 151.5 ± 10.6 ka (weighted mean = 143.0 ± 24.2 (2σ) ka; Priya et al., 2022). Using the locality data derived from our historical research, we can now constrain the age of the fossil material collected by Reddan, Stirling and Zietz in 1908 to fall within the dated sediment units. We are currently completing palaeontological and taphonomic analyses of the 1908 fossil collection and the newly excavated material from Specimen Cave, and this will be presented in a subsequent paper.

Conclusion
Since it was first reported by Europeans in the mid-1800s, Specimen Cave has played an important role in the history of fossil discovery at Naracoorte. Not only did it yield some of the first remains of extinct Pleistocene mammals for the Naracoorte Caves, but it also provided the first Thylacoleo carnifex fossils from the region, including parts of the postcranial skeleton. According to the letter written by William Reddan in 1908, he collected a fossil sample from the area of Specimen Cave corresponding to our new excavation pit. This letter also confirms that Reddan and his team of workers created the large hole opening into the lower, southeast trending passage where our new excavation pit is located. This hole was created to improve access to the underlying passage and fossiliferous sediments later excavated by Stirling and Zietz in 1908 following communication with Reddan. Newly discovered cave writing adjacent to the excavation site indicates Reddan visited the cave as early as 1890, 18 years before his discovery of the T. carnifex cranial remains. Importantly, the locality information elucidated by our historical research has allowed the fossils collected in 1908 to be constrained within the modern geochronological context.
This study demonstrates the value of investigating the modern history of fossil sites and shows the importance of historical cave writing and the need for preserving it. Historical investigations are particularly beneficial when analysing fossil collections with limited locality data, as they can help to provide geochronological and stratigraphic context. An understanding of the history of visitation to caves is also important for interpreting their current physical condition and the degree of anthropogenic damage inflicted to them. PAGE 3 OF LETTER each other. There is a great difference in their relative depths from the surface. The drift sand in the newly found cave cannot be more than 30 feet from the surface at the north end. The place where the Lions [Lion's] tooth was found is full 80 feet. The latter is under a hill about 20 feet higher than the surface tat New Cave opening. There is none of this red sand in the Bat Cave, notwithstanding that it is much deeper than the other. The drift in the Bat Cave was depo -sited in layers of various colors [colour] & evidently, at different times The Lions [Lion's] tooth was found in a deposit of Bat excreta. There were two channels of ingress. beside [stricken] as well as the natural opening at north end of this cave. The drift sand is Similar wherever found, except some red coarse sand on the floor of the channels, as seen from within the Cave. One of thes [these] places of ingress is within 30 yards of the north end of the new cave -between the two caves in a direct line. The red sand is present in every cave and fissure found south of the Bat Cave (I mean those found this year) none of these had visible openings. X There's none or very little of this red sand found in any of the old set of caves, with the exception of the ('Specimen Cave") yet all these had visible openings. X The new cave which contains so much of this red sand was found under peculiar circumstances. I was walking in the ferns some months ago & notices a round depre -ssion in the sand. a small place but forming a circle. Were it not for its form it would seem as if a rabbit burrow or wombat hole had caved in. It was so shallow that I almost dismissed it from my mind. I thought if it over a cave, all the sand would have gone through. On the other hand if there was only room underneath for the little that sank, the place would be very shallow. After giving the matter a little thought I decided that it was a sand pipe and that the bottom had just given way.
PAGE 4 OF LETTER given way. I had the sand cleared away down to the rock & found the sand pipe about 18 in diam.
With great difficulty we cleared out this sand as one [?] could only stand upright in it with his hands above his head. It opened out a little at the bottom so that a man could stoop & scrape the sand into a small vessel. A small hole had been eaten through the bottom of the pipe about the size of a mans [man's] foot. This hole was gradually enlarged untill [until] the smallest of the men could get through. Then the opening was enlarged from the inside. The result was the discovery of a very beautiful large cave 5 chains long and a chain or so wide.
Some of the formations are phenominal [phenomenal] in their design and beautiful in their freshness and purity.
I would not mention these matters but for the formation of the cave -The Sand it contains, its being evidently cut off from its near neighbour -the bat Cave. The traces of animals (evidently wombats) Which there was absolutely no opening any where [anywhere] in the roof exept [except] the little hole so providentially discovered. Theres [there's] a wombat warren about 10 chains west of the cave and to get here the animals -whatever they were -had to come that distance through the fern hill. When you have decided what you will do. Please communicate with the Conservator of Forests. I have two workmen (the same who found the bones) engaged at particular work & when finished with it, they would probably discharged.
The work will not be finished for about 10 days or so.