4. Plant inclusions: their contribution to the understanding of vegetation,
4.1 Conifers
4.1.1 Unexpected conifer diversity of the Baltic amber flora
Conifer inclusions from Baltic amber are of particular interest, since one (or several) of them might be the Baltic amber source plant. During the last centuries, numerous authors published comprehensive studies about coniferous inclusions from Baltic amber and described numerous taxa (Goeppert and Berendt 1845, Goeppert 1853, Goeppert and Menge 1883, Conwentz 1886a, 1890, Caspary and Klebs 1907).
Czeczott (1961) revised this literature of plant inclusions from Baltic amber, including conifers, and established a list of fossil plants from Baltic amber. She further excluded synonyms and false identifications, as well as plant fossils which were listed as amber inclusions, but actually were found nearby or impressed on amber. Among conifers, Czeczott (1961) named 33 fossil species (see Tab. 5 for an amended list), including Pinaceae (3 genera, 11 species), ‘Taxodiaceae’ (2 genera, 4 species) and Cupressaceae (5 genera, 18 species). Taxa in addition to those listed by Czeczott (1961) were published by Pielińska (2001), Jähnichen (1998) and Dörfelt and Schmidt (2007) who described four additional taxa (Cupressus sp., Picea baltica, Thuja sp. and Taiwania schaeferi) from Baltic amber. A further literature-based summary was presented by Spahr (1993) who published a comprehensive bibliography about plant inclusions, including Baltic amber. However, until a recent study (Sadowski et al. 2017a [5]), no revision of coniferous plant inclusions, which was based on literature and amber specimens, including holotype material, was published.
Sadowski et al. (2016a [3], 2017a [5]) verified ten genera of four conifer families, including several holotype specimens (Tab. 5). In comparison to the revision of Baltic amber conifers by Czeczott (1961), new taxa were added to the list (Tab. 5). Czeczott (1961) named three genera of Pinaceae (Abies, Pinus and Picea) of which two (Abies and Pinus) were confirmed by Sadowski et al. (2017a [5]).
These authors also added further genera which were previously unknown from Baltic amber. Thus, the number of pinaceaous genera from Baltic amber increased to five (Abies, Cathaya, Nothotsuga, Pinus and Pseudolarix).
In their revision of needle inclusions of Pinus species, Sadowski et al. (2017a [5]) distinguished four species: Pinus baltica, P. cembrifolia, P. serrata and P. aff.
schiefferdeckeri, including one species (P. serrata) that Czeczott (1961) had eliminated from her list. A further species, P. silvatica, was found to be synonymous with P. cembrifolia and can thus be excluded from the list of conifers from Baltic amber. Due to missing holotypes, Sadowski et al. (2017a [5]) could not revise four further pine species (Pinus banksianoides, P. dolichophylla, P. künowii, P.
triquetrifolia) which were described from Baltic amber over 100 years ago (see Tab.
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Tab. 5: Updated list of coniferous inclusions from Baltic amber, taken from Czeczott (1961; and references therein) and based on more recent studies (see references). Revised taxa are indicated by *; recently verified taxa are highlighted in blue; doubtful taxa are highlighted in red; taxa mentioned by Pielińska (1990) in a shortened list without further details are indicated by †.
Name Kind of remain Comment Reference
Cupressaceae
Athrotaxis† ? Pielińska 1990
Calocedrus sp. twig fragments Sadowski et al. 2017a [5]
Chamaecyparis casparyi* twig fragment
male cone shoot type 2 Czeczott 1961; Sadowski and Kunzmann
(unpublished) Chamaecyparis massiliensis*†
twig fragments
shoot type 1 Czeczott 1961; Pielińska 1990; Sadowski and Kunzmann (unpublished)
Caspary and Klebs 1907; Czeczott 1961;
Sadowski and Kunzmann (unpublished) Cupressites schenkii
Cupressites Brongniart 1828 is based on a vegetative shoot from the lower Triassic, and should not be retained for Eocene cones
Cupressinanthus magnus* affinities to ?Glyptostrobus (pollen cone type 3)
Glyptostrobus europaeus* twig fragments affinities to ?Cupressospermum saxonicum (shoot type 3)
Caspary and Klebs 1907; Kunzmann 1999;
Sadowski et al. 2017a [5]; Sadowski and Kunzmann (unpublished)
Quasisequoia couttsiae Sadowski et al. 2017a
Sequoia sternbergii Caspary and Klebs 1907; Czeczott 1961
Sequoia couttsiae* ?Quasisequoia couttsiae Caspary and Klebs 1907; Czeczott 1961;
Sadowski et al. 2017a [5]
Sequoia brevifolia Caspary and Klebs 1907; Czeczott 1961
Sequoia langsdorfii† Pielińska 1990
Taiwania schaeferi* synonym of Quasisequoia couttsiae Jähnichen 1998; Sadowski et al. 2017a [5]
Taxodium sp. Sadowski et al. 2017a [5]
Thuites succineus* shoot type 1
Caspary and Klebs 1907; Czeczott 1961;
Knobloch 1971; Sadowski and Kunzmann (unpublished)
Thuites carinatus Thuites introduced by Sternberg 1825
is not equivalent to Thuites from Baltic amber
Thuites lamelliformis Thuites borealis
Thuja sp.† Pielińska 1999, 2001
Widdringtonites oblongifolius* synonym of Quasisequoia couttsiae Caspary and Klebs 1907; Czeczott 1961;
Sadowski et al. 2017a [5]
Widdringtonites oblongifolius
var. longifolius type material of mid-Cretaceous
Widdringtonites lacks confirmation
Caspary and Klebs 1907; Czeczott 1961; L.
Kunzmann (pers. comm.) Klebs 1907; Czeczott 1961; Sadowski et al.
2017a [5]
Abies linearis*
Abies suckerii*
Picea engleri Conwentz 1890; Czeczott 1961
Picea baltica seedling provisional description Dörfelt and Schmidt 2007
Cathaya sp.
needles
Sadowski et al. 2017a [5]
Nothotsuga protogaea Sadowski et al. 2017a [5]
Pinus baltica* Conwentz 1890; Czeczott 1961; Sadowski et
al. 2017a [5]
Pinus banksianoides Goeppert and Menge 1883; Czeczott 1961
Pinus cembrifolia* synonym of Pinus silvatica
Caspary 1886; Conwentz 1890; Caspary and Klebs 1907; Czeczott 1961; Sadowski et al.
2017a [5]
Pinus dolichophylla
Caspary and Klebs 1907; Czeczott 1961 Pinus künowii
Pinus serrata* Caspary and Klebs 1907; Sadowski et al.
2017a [5]
Pinus aff. schiefferdeckeri* synonyms of ?Pinites rigidus, ?Pinus subrigida, ?Pinus rigida
Goeppert and Berendt 1845; Goeppert 1853;
Goeppert and Menge 1883; Caspary and Klebs 1907; Czeczott 1961; Sadowski et al.
2017a [5]
Pinus silvatica* synonym of Pinus cembrifolia Goeppert and Menge 1883; Czeczott 1961;
Sadowski et al. 2017a [5]
Pinus triquetrifolia Goeppert and Menge 1883; Czeczott 1961
Pseudolarix Sadowski et al. 2017a [5]
Sciadopityaceae Sciadopitys cf. tertiaria
needles
Sadowski et al. 2016a [3]
Sciadopitytes glaucescens*
?angiosperm leaves Goeppert and Menge 1883; Czeczott 1961;
Sadowski et al. 2016a [3]
Sciadopitytes linearis*
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5). Czeczott (1961) estimated that about eight Pinus species are to be expected from Baltic amber. However, Czeczott (1961) only considered pine needle inclusions and excluded male cones and wood inclusions of Pinus from her list, arguing that they might represent the same species as the needles. This procedure is arguable, since specimens are excluded whose affinities are not clarified yet. This could artificially delimit the actual species number of Pinus from Baltic amber and thus, Czeczott’s (1961) list also needs further revisions in the future. Based on the new findings of Sadowski et al. (2017a [5]) it is evident that at least four Pinus species existed in the Baltic amber flora (Tab. 5). However, more studies on pine needle inclusions are needed to restudy all Pinus species that Czeczott (1961) excluded from her list.
In the case of Abies, Sadowski et al. (2017a [5]) revised holotypes from historic amber collections along with literature descriptions and images. They showed that Abies species exclusively described from Baltic amber (A. obtusifolia, A.
linearis and A. suckerii), are actually interpreted as angiosperm leaves (Dicotylophyllum var. sp.) and thus, should be removed, when updating Czeczott’s (1961) list (Tab. 5). However, Sadowski et al. (2017a [5]) found a non-described specimen in a private amber collection that exhibited clear affinities to Abies and thus, confirmed the occurrence of firs in the Baltic amber flora.
From nine listed cupressaceous genera from Baltic amber, Sadowski et al.
(2017a [5]) only verified three genera (Calocedrus, Quasisequoia and Taxodium) that were not listed as such by Czeczott (1961). Baltic amber inclusions with affinities to Taxodium were already published by Goeppert and Berendt (1845), and Goeppert and Menge (1883). Caspary and Klebs (1907), however, doubted affinities of the specimens to Taxodium. The respective specimens are currently lost, and therefore, the new fossil evidence represents the first unambiguous record of Taxodium from Baltic amber (Sadowski et al. 2017a [5]).
Czeczott (1961) listed Sequoia couttsiae which is a basionym of Quasisequoia couttsiae. The particular specimen is a twig fragment inclusion which was described and pictured by Caspary and Klebs (1907) as S. couttsiae. Sadowski et al. (2017a [5]) revaluated these descriptions and images, since the original specimen is currently lost. They showed that its assignment to Q. couttsiae cannot be clearly verified. However, Sadowski et al. (2017a [5]) presented unambiguous specimens of Q. couttsiae, confirming its occurrence in the Baltic amber flora.
Sadowski et al. (2017a [5]) further evaluated Widdringtonites oblongifolius and Taiwania schaeferi that were listed by Czeczott (1961). These named taxa are synonymous with Quasisequoia couttsiae and thus, should be removed when updating Czeczott’s (1961) list. Further putative representatives of Widdringtonites (W. lanceolatus, W. oblongifolius var. longifolius) should be excluded from the list as well, according to preliminary research results of L. Kunzmann and J. Kvaček (pers.
comm. L. Kunzmann, Dresden). Both authors are currently restudying type material of Widdringtonites from the Cenomanian Peruc-Corycany and Niederschöna formations in the Czech Republic and Germany. The leaf micromorphology of Widdringtonites is still poorly known and needs further investigation. When revisions of its type material are available, Paleogene fossils of Widdringtonites have
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to be restudied and revised, as well. Hence, this mid-Cretaceous taxon should not be applied to accommodate cupressaceous twig remains from Baltic amber yet (pers.
comm. L. Kunzmann, Dresden).
Including the new results, the number of Baltic amber Cupressaceae genera of Czeczott’s amended list decreases from 16 to 14 (Tab. 5); however, the majority of cupressaceous amber genera still lack verification and thus, more research is needed to revise the remaining Cupressaceae taxa from Baltic amber. Preliminary results on cupressaceous inclusions from Baltic amber (established by L. Kunzman and I; see chapter 4.1.2), however, already confirmed their high (taxonomic) diversity.
Besides Pinaceae and Cupressaceae, Sadowski et al. (2017a [5]) added a further family (and species) to the list of Baltic amber conifers, the extinct Geinitziaceae with Cupressospermum saxonicum. In addition, the new findings of Sciadopitys inclusions from Baltic amber (Sadowski et al. 2016a [3]) finally increased the number of conifer families from Baltic amber from two to four (Tab.
5). Although reports of Sciadopitys from Baltic amber were already published (Goeppert and Berendt 1845, Goeppert and Menge 1883), illustrations and descriptions of these specimens showed that their affinities were doubtful (Sadowski et al. 2016a [3]). Furthermore, the whereabouts of the respective type specimens are unknown. Thus, the new fossil evidence from Baltic amber presented by Sadowski et al. (2016a [3]) unambiguously proves the presence of Sciadopitys in the Baltic amber flora.