Fossiliferous Cretaceous amber from Myanmar (Burma) : its rediscovery, biotic diversity, and paleontological significance

72 Pages·2002·7.1 MB·English

by  Grimaldi, David A

AMERICAN MUSEUM
Novitates
PUBLISHED BY THE AMERICAN MUSEUM OF NATURAL HISTORY
CENTRAL PARK WEST AT 79TH STREET, NEW YORK, NY 10024
Number 3361, 71 pp., 44 figures, 2 tables March 26, 2002
Fossiliferous Cretaceous Amber from Myanmar
(Burma): Its Rediscovery, Biotic Diversity, and
Paleontological Significance
DAVID A. GRIMALDI,! MICHAEL S. ENGEL,? AND PAUL C. NASCIMBENE?
CONTENTS
FCA ORG, Same a ERAT art UeR ock Feta Ie otS A eens AEE PER kei OY oto N Reni ie AAA ee AT ATS PO AON Re 3
TCU crt tare as ile aT hata csctactentegs UEP Nah aeR emera ys ca be eke tati ee Stel «acne tate OR A Tl Mensa fs 3
MIATA Sea tial ONICUTOUS Se simueite ge eum ore tmralen rls Sek esvnemeaiest Ba yenca ee tstntmymeg eer CER) op tannins 6
RESULT Geet opti ced Ue eR eR Rt ee PREM E pectaiiel otra by 2,S ARS el Nr MOMs tie 2.. OS 8
TaphonGinic ObservaliOnse-s66eco eK 8 AR Aa Ss SAR ReRee alee agin ROR A Bee BU eS 8
aK OTIC UVSTS IL snd cog ae Wes nara TG Wena, owed Veet ee:A RN see arare Wy Ee no Os 8
NEAVG eRe hot a, Feo ere OO Beanie Ws. 0 nee POINT AEA RLE. WL iriko eR eso ch Matar I,M .D tN PL, Osc ree R Ee 9
FWO VUGIONEE : oe Rel EN, See ED ten RR CORAM Ct DRE Ce AD See eT en BARRY LL eee 22
IN STTAG OAS bl) eh ed Py oh hege ed 3-4 EAN amas aay Moe Fy Mtga d gep teies cle ee aba IMR 22,
PTGSO Ac Saniyede tay: atac onthnin iii 2 as sp haay ciety nSelie Tol. nbn ner a So tubal AB 24
PEL VC INO MOC A 8 each orgs case BPO te eee ae tli, ty Me oe ahs neha a: an Ae pees Ree oe 24
PETC OPOUAN ul Bese cct ee tt PORE At: NR Re ta den, NutP lt Peli t oot eS Mee, 21
ChelCerala: tse ss OLE eS Bee ks Oe die eee Te ek eae. a Bee Ode pe:
TSE CLAS Ped. ce Bore Oi alin Rte g,p lang tela a gs ey Ss sy Se ces, pe eer ohn Re 31
OCHO PTET, yarn Fes. oo 55-05 Rha 8 DF qu en Note aes ole nee pe tutes et Glp hael mee 31
PERDTATECTA mares ne gs ohh Melina hip( EMail one's athe se Sh Goce ee Saas FUN oec oh eoR y 31
EMTs a i. « obsk e eee Os oo Sls Det heg EW A keine ncaa Dhue seeesee ately. & 31
' Curator, Division of Invertebrates, American Museum of Natural History. e-mail: [email protected]
? Research Associate, Division of Invertebrates, American Museum of Natural History; Assistant Professor, De-
partment of Ecology and Evolutionary Biology and Curator, Division of Entomology, Natural History Museum and
Biodiversity Research Center, Snow Hall, 1460 Jayhawk Boulevard, University of Kansas, Lawrence, KS 66045-
T7523.
3 Curatorial Specialist, Division of Invertebrates, American Museum of Natural History. e-mail: [email protected]
Copyright © American Museum of Natural History 2002 ISSN 0003-0082
2 AMERICAN MUSEUM NOVITATES NO. 3361
|g Fors 8 @1K elk e RARER ea Cc MON anh RiaG PE MTSE Nach. SeA RES Se ys SUR at ateP eP ane MTT ace 30
PE062s ha )C s)e Re eth e ee AEE LS rd EPL. mime eA es. OD BetR MNe. uADi BS a EEE A MRN 2) ated ta ee 34
| ajo peNe: Pt ee ere Or a Pe aca: TtT eR e en 7,A che, SR, Me #2 eth ThA D 3S
Heimipterds |. hare 2k bs de Mie crc Be hh 4 4 ay Bee ae tae teene, 3D
INSU SGT IGA ols Bcc Soe wine Bia! Sreeotencslen mat ene edn l mets os Youre ae esate coats est eg aaa hp 42
BcFei0 )0) K o) 2h art Cm dB eo yn ag Coates Pato t AB on Re Ah AO AMORA ayes teret TSK Jae 45
EPVIMENOPTSRA Aes sees vate cece 5.s orcery RO, PU BE RR aoe « sogerenecersy 48
Diptera, Sic hatter gett il ge Sei, oh nistettityec bata cb coger eis, 5 52
CONCITS IONS Tu) cam oka yo Rien eR enh eerie Solin nara Radler oer s pea e Ee era ie Un er ae, 58
Biostratipraphie Chronglogy 5222227952 eee One aioe ds SERRATE! Be oh eR Os 58
Tax OnOMmce UDIVErsiGy. Aas hein io aire e EE Peet anal Ree EGS, tiem ante ree Reg aar enee ree 61
Pale Oe ny PO ents fn 5 eR vec en ous Gre ou aes 8 he ne Ce erie eis oe eee uld! s 2a 63
PC ITAO WNS CHEN IIS ser Be aseynat Shorts ate epee UUs php tetgt Mitra ght Mra Fa av heme tac ay c Mareg en eN, torah hn See ethS 64
ReEtSrenCESE= 2 FLAK cot ce BN ot Pry hace pet e Ot i he ies lace, Bache Py inda hd acep oe a 6 TE ce eo, 65
2002 GRIMALDI ET AL.: BURMESE AMBER
ABSTRACT
Amber from Kachin, northern Burma, has been used in China for at least a millennium for
carving decorative objects, but the only scientific collection of inclusion fossils, at the Natural
History Museum, London (NHML), was made approximately 90 years ago. Age of the material
was ambiguous, but probably Cretaceous. Numerous new records and taxa occur in this amber,
based on newly excavated material in the American Museum of Natural History (AMNH)
containing 3100 organisms. Without having all groups studied, significant new records and
taxa thus far include the following (a + refers to extinct taxa): For Plants: An angiosperm
flower (only the third in Cretaceous amber), spores and apparent sporangia of an unusual but
common fungus, hepatophyte thalli and an archegoniophore of Marchantiaceae, and leafy
shoots of Metasequoia (Coniferae). Metasequoia is possibly the source of the amber. For
Animals: Mermithidae and other Nematoda; the oldest ixodid tick (a larval Amblyomma); bird
feathers; and the only Mesozoic record of the Onychophora (‘“‘velvet’? worms), described as
+Cretoperipatus burmiticus, n. gen., n. sp. (Peripatidae). Poinar’s classification of the Ony-
chophora is substantially revised. Still largely unstudied, the fauna of mites (Acari) and spiders
(Araneae) appears to be the most diverse ones known for the Mesozoic. For Insecta: Odonata
indet. (wing fragment); Plecoptera indet.; new genera of Dermaptera, Embiidina, and Zoraptera
(the latter two as the only definitive Mesozoic fossils of their orders). Within Hemiptera, there
are primitive new genera in the Aradidae, Hydrometridae, Piesmatidae, Schizopteridae, and
Cimicomorpha (Heteroptera), as well as in {Tajmyraphididae (Aphidoidea), and +Protopsyl-
lidiidae. An adult snakefly (Raphidioptera: +Mesoraphidiidae) is the smallest species in the
order, and new genera occur in the Neuroptera: Coniopterygidae, Berothidae, and Psychopsi-
dae, as well as larvae of apparent Nevrorthidae. Coleoptera are largely unstudied, but are
probably the most diverse assemblage known from the Cretaceous, particularly for Staphylin-
idae. An adult lymexylid, the most primitive species of Atractocerus, is the first Mesozoic
record of the family. In Hymenoptera there are primitive ants (Formicidae: Ponerinae n. gen.,
and +Sphecomyrma n.sp [Sphecomyrminae]), the oldest record of the Pompilidae, and signif-
icant new records of }Serphitidae and +Stigmaphronidae, among others. Diptera are the most
diverse and abundant, with the oldest definitive Blephariceridae and mosquito (Culicidae), as
well as new genera in the Acroceridae, Bibionidae, Empidoidea; a new genus near the enig-
matic genus Valeseguya, and an unusual new genus in the +Archizelmiridae. *Chimeromyia
(Diptera: Eremoneura), known previously in ambers from the Lower Cretaceous, is also rep-
resented.
The stratigraphic distribution of exclusively Mesozoic arthropods in Burmese amber is re-
viewed, which indicates a probable Turonian-Cenomanian age of this material (90-100 Ma).
Paleofaunal differences between the NHML and AMNH collections are discussed, as is the
distinct tropical nature of the original biota. Burmese amber probably harbors the most diverse
biota in amber from the Cretaceous, and one of the most diverse Mesozoic microbiotas now
known.
INTRODUCTION and jade. Use of it as a precious and semi-
precious substance abruptly ended, though,
Of all the world’s amber deposits, perhaps
by approximately 1940, and despite the work
none has more mystique than those from
of an insightful entomologist made 80 years
northern regions of Myanmar. “‘Burmite,”’ ago, its scientific significance has been con-
along with jadeite from nearby mines, was
fused and only recently recognized.
exported to China since at least the first cen- The first significant geological investi-
tury A.D. for use in jewelry and carved objets gation of Burma’s amber was by Noetling
d’art (Laufer, 1906; reviewed in Grimaldi, (1892, 1893), who reported the most pro-
1996; Zherikhin and Ross, 2000). Baltic am- ductive sites in the Hukawng Valley of the
ber had been prized for 10 millennia before northern state of Kachin, specifically south-
this in northern Europe, but in Asia the prox- west of Maingkhwan (26°20'N, 96°36’E).
imity of Burmese amber, and probably its Four other regions in Burma have histori-
deep red color, hardness, and glassy polish, cally yielded amber (reviewed in Zherikhin
made it particularly sought along with ivory and Ross, 2000), but none as prolific and
- AMERICAN MUSEUM NOVITATES NO. 3361
commercially exploited as in the Hukawng among the plethora of taxa with which he
Valley. Noetling mentioned inclusions of worked. As a result, he was able to recognize
insects and plants, and perceptively noticed that the arthropods in Burmese amber (and
that the newly excavated amber pieces ap- therefore the amber itself) were older than
peared weathered and may have been trans- the surrounding sediments, perhaps even
ported some distance before redeposition. Cretaceous in age:
H.L. Chhibber visited the Hukawng Valley
They [the arthropods in Burmese amber] are, indeed,
in 1930, and made many additional obser- related to living forms; but in practically every case
vations. He reported the amber to occur in to precisely those forms which we have thought of as
thin lignite seams among clays and shales ancient, as remnants of a very old fauna. So... it is
difficult to avoid a strong suspicion that the amber,
(Chhibber, 1934). The larger, transparent
though found in Miocene clay, is actually very much
pieces of amber were buried between 10— older, conceivably even Upper Cretaceous. (Cocker-
15 m, and to reach it miners excavated nar- ell, 1917a: 360).
row shafts with walls supported by bamboo Until approximately the 1960s, the Creta-
screens. Beyond this depth, ground water
ceous was one of the poorest known geolog-
would fill the shaft. Presence of the fora-
ical periods for insects; now there are over
miniferan Nummulites biarritzensis indicat-
30 major Cretaceous deposits yielding in-
ed a middle Eocene age of the sediments,
sects (see, for example, the summary in Ev-
though Chhibber acknowledged that the
enhuis, 1994). Despite this deficiency, and
amber was possibly reworked from older
Cockerell’s early suggestion that Burmese
sediments. He also reported that amber was
amber was Cretaceous, there was very little
mined most abundantly near the villages of
research on the NHML collection between
Khanjamaw (26°15’'50"N, 96°33'37”E),
1921 and 1995, nor were there any recorded
Ladummaw (26°11'19"N, 96°28'48"E), and
attempts to excavate additional Burmese am-
Lajamaw (26°15'N, 96°28’E). His obser- ber for study of the inclusions. In 1995, Al-
vation that some areas reported by Noetling exandr Rasnitsyn, of the Paleotological In-
were pocked with abandoned mines may
stitute, Moscow, and Genady Dlussky, of
have led to the popular notion that the min- Moscow State University, studied Hymenop-
ing of Burmese amber, by and large, was tera and specifically ants, respectively, in the
depleted or abandoned (e.g., Fraquet, NHML collection of Burmese amber. Ras-
1987).
nitsyn (1996b) noted the presence of the ex-
According to the records of the Geological
tinct Cretaceous family +Serphitidae and the
Survey of India, 82,000 kg of Burmese am- subfamily +Iscopininae (Hymenoptera).
ber were excavated between 1898-1940 Dlussky (1996) described a bizarre ant,
(summarized by Zherikhin and Ross, 2000). +Haidomyrmex, from the NHML collection,
Curiously, only one collection of Burmese which he placed in the Cretaceous subfamily
amber is known that was made for scientific +Sphecomyrminae. Mounting evidence that
purposes. This collection consists of 117 Burmese amber was Cretaceous led to a co-
pieces containing approximately 1200 organ- ordinated study of the NHML collection, or-
isms in the NHML. It was assembled by ganized by Andrew Ross (NHML). Produc-
R.C.J. Swinhoe of Mandalay between 1915 tive as Cockerell was, he touched on but a
and 1916, and sent to a prolific entomologist fraction of the organisms in the NHML col-
in Colorado, T.D.A. Cockerell (1866-1948). lection of Burmese amber. In a recent issue
Cockerell is renowned for having written (vol. 56, no. 1) of the Bulletin of the Natural
nearly 4000 articles on various subjects (We- History Museum (Geology Series) [London],
ber, 1965), but particularly the systematics of eight papers describe 15 new species of ar-
living and fossil insects. Between 1916 and thropods in six orders from that collection.
1921, Cockerell published 13 papers on 41 Therein are also extremely useful summaries
new arthropods in Swinhoe’s collection, then of described species in Burmese amber (Ross
donated the collection to the NHML. Cock- and York, 2000), and a list of arthropod fam-
erell described perhaps 7000-8000 species ilies (Rasnitsyn and Ross, 2000).
during his lifetime, but also had an uncanny Adding to the renewed interest in Burmese
ability to recognize natural relationships amber, we are able to report a new collection
2002 GRIMALDI ET AL.: BURMESE AMBER 3
TABLE1
Summary of Major Fossiliferous Cretaceous Amber Deposits
Present Paleo-
Location Age latitude latitude References
Burma ?Cenomanian 25,5°N 12°N Zherikhin and Ross, 2000; this paper
Lebanon Barremian-Aptian 34°N 10-15°N Azar, 2000; Scotese, 1991; Zharkov et al., 1995:
Channel] et al., 1996
New Jersey Turonian 41°N 40°N Grimaldi et al., 2000a; Scotese, 1991; Zharkov
et al., 1995
Spain Aptian 43°N 25-35°N Alonso et al., 2000; Scotese, 1991; Zharkov
et al., 1995
W. Canada Campanian 50°N 55°N Pike, 1995; Scotese, 1991; Zharkov et al., 1997
Siberia Albian-Santonian T4°N 60-70°N Zherikhin and Eskov, 1999; Zharkov et al.,
1995, 1997
of fossils in amber assembled from material the Cretaceous. Disparity in the results is
that was recently excavated from the Hu- probably due to approaches that use taxic
kawng Valley in northern Burma—the only analyses (e.g., numbers of insect families)
new scientific specimens of the material ob- versus phylogenetic analyses (see Grimaldi,
tained in over 80 years. The collection con- 2000a). Compared to dramatic extinctions of
tains nearly three times the number of inclu- non-avian dinosaurs, ammonites, rudist bi-
sions as the NHML collection, and many valves, and other taxa by the K/T boundary,
new taxa and records not represented in the extinctions of insects are barely noticeable,
NHML collection. Moreover, our findings and may be obscured by the impressive ra-
not only corroborate a Cretaceous age of diations of insects just prior to this time.
Burmese amber, but also suggest an origin Besides preserving a rich fauna from a bi-
that is probably mid-Cretaceous. ologically important time period, Burmese
The Cretaceous is one of the most bioti- amber preserves organisms with a lifelike fi-
cally significant periods in the evolution of delity for which amber is renowned (Gri-
terrestrial life since the angiosperms explo- maldi, 1996). Such complete preservation
sively radiated in the upper part of the Lower vastly improves interpretation of extinct spe-
Cretaceous (Crane et al., 1995). Given the cies.
great diversity of extant insects intimately as- Lastly, the location of Burmese amber also
sociated with angiosperms, evolution of the makes it highly significant. It is the only ma-
two groups would presumably be inextrica- jor, fossiliferous deposit of Cretaceous amber
bly linked. One study found, however, that in southeastern Asia, and one of two of the
there was no increase in the number of insect most southerly deposits of fossiliferous Cre-
families in the Cretaceous during or imme- taceous amber. All other major deposits of
diately following the angiosperm radiations Cretaceous amber occur between 34° and 74°
(Labandeira and Sepkoski, 1993), but in fact N latitude (Table 1), but why they are re-
there was a slight slump in family numbers. stricted to the Northern Hemisphere is an
Other taxic analyses found a profound radi- enigma. Paleolatitude of the Burmese and
ation of Cretaceous insects (Jarzembowski Lebanese amber deposits (10—15°N) are the
and Ross, 1993, 1996; Ross et al., 2000). most southerly of all major Cretaceous am-
Phylogenetic studies on speciose families of ber deposits. As discussed at the end of this
insect pollinators (Engel, 2001; Grimaldi, paper, climatic effects from paleolatitude
1999), herbivores (Farrell, 1998), and major were probably profound. Ages, locations,
consumers (Grimaldi and Agosti, 2000; Gri- and references for the major deposits of fos-
maldi et al., 1997; Thorne et al., 2000) in- siliferous Cretaceous amber are the follow-
dicated explosive radiation of these groups in ing:
6 AMERICAN MUSEUM NOVITATES NO. 3361
LOWER CRETACEOUS: LEBANON and Chhibber (1934). Apparently, miners need to
JORDAN, ranging from the Lower to Upper reach lignitic seams some 30—40 cm thick to
Neocomian (Berriasian to Aptian, and a mi- obtain the amber, which can occur at depths
nor incursion into the Albian; Azar, 2000); of up to 12 m. In 2000, nearly 80 kg of crude
SPAIN (Nograro Formation of Alava, upper amber was mined. Samples of various colors
Aptian and middle Albian; Alonso et al., were analyzed using Pyrolysis-Gas chroma-
2000); and RUSSIA, Taimyr Peninsula of tography (PyGC) and PyGC-Mass Spectros-
northern Siberia (Ogneva Formation, Aptian copy (e.g., Shedrinsky et al., 1991; Grimaldi
to Albian; Zherikhin and Eskov, 1999). Sev- et al., 2000a), which matched identically to
eral smaller deposits in Japan and England each other and to samples from the NHML
have also yielded insect fossils (summarized collection (A. Shedrinsky, unpubl. data on
by Grimaldi, 1996; Ross, 1998). file in the Invertebrates Division, AMNH).
UPPER CRETACEOUS: CANADA (western), Material from the outcrops of the 1999 and
Cedar Lake, Manitoba and Medicine Hat, Al- 2000 excavations may be different from that
berta (McAlpine and Martin, 1969), and reported by Chhibber (1934) and earlier
Grassy Lake, Alberta (Pike, 1995). The workers, but their proximity and chemical
Grassy Lake and Medicine Hat deposits be- identity indicates an identical botanical ori-
long to the Foremost Formation, Judith River gin with the historical collections and, thus,
Group (Campanian, possibly Santonian). probably a very similar or identical age.
RUSSIA: Taimyr Peninsula, Siberia, from Approximately 75 kg of raw Burmese am-
Agapa and belonging to the Dolgan Forma- ber were shipped to the AMNH by Leeward
tion (Cenomanian), and from Yantardakh, Capital, where it was treated in lots of ap-
Kheta Formation (Santonian). Zherikhin and proximately 3 kg, using a 50% solution of
Eskov (1999) also reviewed other localities muriatic acid (HCl) to dissolve veins of cal-
in the former USSR. USA: New Jersey (Rar- cite that permeated most pieces. This greatly
itan Formation, Turonian; Grimaldi et al., improved visibility into the amber. The am-
1989; 2000a). The paleobiota of New Jersey ber was then washed thoroughly with water,
amber is the most diverse one reported thus and carefully screened for organismal inclu-
far, even though the deposit that yielded most sions piece by piece. The amber was kept
of the amber was extremely localized. Very wet during screening in order to improve vis-
likely the Burmese amber biota will be found ibility. Screening was done under a stereo-
to be more diverse than any other Cretaceous scope (approximately 20 magnification) us-
amber deposit, including amber from New ing transmitted and oblique reflected light.
Jersey. For many pieces, one or more surfaces need-
ed to have a “‘window”’ polished into the sur-
MATERIALS AND METHODS ficial rind in order to locate and view inclu-
sions. This was done using a Buehler Ecomet
Bags of crude amber were purchased by water-fed flat lap with abrasive discs (320,
Leeward Capital Corporation, a Calgary- 600, 800, 1200 grits). Because Burmese am-
based mining company, from local sources ber is exceptionally hard compared to other
near the village of Tanai. Tanai is on the ambers, it was generally possible to trim off
Ledo Road in Kachin State, close to the his- some amber surrounding an inclusion with-
torical sources of Burmese amber in the Hu- out the piece splitting or crumbling. Hard-
kawng Valley (fig. 1). Mining specifically oc- ness of Burmese amber allows surfaces to be
curs approximately 32 km southwest of Tanai polished with a glassy finish. Trimming was
near Noye Bum (“hill”’, approx. 250 m). done with a fine (1.5 mm thick) diamond,
Since initial exploration in 1999, Leeward water-fed, circular trim saw; the sawed sur-
has joined with a local Kachin mining com- faces were ground with successively finer
pany (Buga Company Ltd.) for exploitation grits, and then polished with a lum alumina
of the amber deposits, under the jurisdiction polish. This optimized the penultimate step
of the Myanmar Ministry of Mines and mil- in preparation: embedding the piece in a
itary officials. Methods of mining the amber highly stable epoxy (Buehler) under vacuum,
remain traditional, just as were described by as described in detail elsewhere (Nascimbene
2002 GRIMALDI ET AL.: BURMESE AMBER 7
a fon 4 *: i
ee ee
Fig. 1. Location of Burmese amber deposits. Above: inset shows approximate area in southeast
Asia. Below: detail within inset.
8 AMERICAN MUSEUM NOVITATES NO. 3361
and Silverstein, 2000). In this process, epoxy amber varied in color from light, transparent
penetrates most fine cracks and thus helps yellow to deep, blood red, but the most abun-
prevent fracturing during the final trimming, dant kind was an orange-colored amber con-
grinding, and polishing. Optimal prepara- taining swirls of fine bubbles and different
tions resulted in a cubic shape, with gener- hues. Pyrolysis gas chromatography—mass
ally no more than a millimeter or two be- spectroscopy on the different forms of amber
tween the inclusion and one or more surfaces indicate a chemically identical substance (T.
of the amber, these surfaces being generally Wampler and A. Shedrinsky, unpubl. data),
parallel to the plane of critical structures. so all of the amber was probably formed by
However, many pieces had multiple inclu- a single species of tree. Botanical identity of
sions that could not be separated, and this the tree that produced Burmese amber is un-
compromises preparation and observation. known, but presence of diagnostic coniferous
This appears to be a particular problem with compounds indicates it certainly was a co-
the pieces from the NHML collection, since nifer, and possibly a cupressaceous tree like
most inclusions occur in large pieces that Metasequoia (see below). Variations may be
were sliced into polished slabs for viewing, a result of amount of predepositional expo-
but no further. sure and of geothermal energy during depo-
All AMNH pieces were given unique, se- sition (for color), and whether the resin was
quential numbers; for pieces with multiple secreted subcortically or externally (for
inclusions each inclusion was lettered (a, b, form). Insects were comparatively rare in the
c,...). Identifications were done, where pos- “‘swirly’’ amber, and when present they were
sible, to at least family level, and a collection often distorted from moderate to extreme
of 1200 pieces and 3100 inclusions was cat- compression, and often also disarticulated.
alogued using the database MS Access. This type of amber preservation is similar to
Printed or diskette copies of the database are that in Paleocene amber from Wyoming (Gri-
available from the senior author for qualified maldi et al, 2000b) and putatively Paleocene
researchers; an electronic version will even- amber from Sakhalin Island (Zherikhin and
tually be available at www.amnh.org. For Eskov, 1999). For Wyoming amber, it is be-
taphonomic purposes we included counts of lieved that extremely deep sediments created
308 arthropod specimens too partial or de- tremendous pressures, which compressed
graded to be of systematic use, and so they most organisms and even organic debris
were not accessioned, cataloged, or databa- within the amber into unrecognizable
sed. Some were identifiable to insect family, ““smears.”’ Another type of Burmese amber
or just as “‘Insecta incertae sedis” or “‘Ar- consisted of flattened, lens-shaped pieces,
thropoda incertae sedis’’. Systematic descrip- which rarely contained insects. Insects were
tion and discussion of various taxa will be most commonly found in pieces shaped like
made in separate papers. flows or runnels; these compromised no
more than 3—4% by mass of all the amber
RESULTS but yielded approximately 85% of the arthro-
pods. Insects in runnel pieces were usually
TAPHONOMIC OBSERVATIONS
well preserved, and sometimes numerous or-
Some 72.21 kg of acid-washed amber (mi- ganisms were found in such a piece merely
nus the dissolved calcite) yielded, on aver- 3 cm long and 1 cm diameter. Clearly, the
age, 46 organismal inclusions per kg (a total runnel pieces were flows of resin secreted in
of 3,408 organisms). This count includes 308 areas or under conditions optimal to entrap-
partial specimens, such as isolated wings of ment of insects.
insects, as well as specimens too poorly pre-
served for identification beyond order or to
TAXONOMIC DIVERSITY
family. Other inclusions (not included in this
figure) were plant stellate trichomes (more The recent collections have yielded signif-
abundant than in any other Cretaceous am- icant new, higher-level taxonomic records for
bers studied thus far), bark fibers, wood frag- Burmese amber, including several plants, the
ments, and insect frass. Individual pieces of phyla Nematoda and Onychophora, and near-
2002 GRIMALDI ET AL.: BURMESE AMBER 9
ly 30 families of Arthropoda (table 2). Col- the portion of the polyp preserved in the am-
lectively based on the NHML and AMNH ber almost always has a cross section of the
collections, the Burmese amber fauna pre- base exposed at the surface. This exposure
serves a remarkable diversity of organisms, allowed decay of the internal tissues in most
including numerous records of earliest oc- specimens; occasionally specimens were
currence and other significance. We briefly found with intact internal contents.
review below those taxa for which at least The sporangia in Burmese amber have no
some family-level identifications were done, apical ostiole, as is found in some antheridia
and ones we considered especially signifi- of hepatophytes having roughly similar
cant. We have not discussed the following shape (e.g., Sphaerocarpaceae). Cuticles
taxa represented in the new AMNH collec- were better viewed using scanning electron
tion, simply because they still require study: microscopy (SEM). This was done by taking
Aves (feathers, currently under study by Car- three pieces with sporangia and cutting a fine
la Dove, Smithsonian Institution), Reptilia groove in each amber piece along various
(skin), Myriapoda, Collembola, Archaeog- axes close to the sporangium, then splitting
natha and Thysanura, Ephemeroptera, Odon- them open. This caused fracturing between
ata (wing fragments only), Blattodea and the cuticle and the amber (fig. 6), or through
Mantodea, Auchenorrhyncha, Pscoptera, the sporangium (fig. 7), depending on how
Thysanoptera, Trichoptera and Lepidoptera. the groove was cut. The exposed sporangia
were then gold coated for examination using
Kingdom PLANTAE a Zeiss DSM-1 SEM. The external surfaces
(cuticle) of the sporangia have a very fine
Plant Antheridia or Fungal Sporangia? geometric sculpturing, similar to herringbone
The most common organismal inclusion in patterns (fig. 6). Under stereoscope magnifi-
the material we screened were polyp-shaped cations (50—100X), this pattern resembles
structures, ranging in size from 2 to 6 mm in fingerprints. Under the SEM at magnifica-
width, which are almost certainly the sporan- tions of 100-1000, no cellular/epithelial
gia of a fungus or possibly plant (figs. 2—7). structure was visible, although in some views
Similar structures occur in the NHML col- minute openings, 3—4 wm in diameter, were
lection (A.J. Ross, personal commun.). They found in fairly regular distribution (fig. 6b),
were never branched or joined at the base, though nothing resembled stomata.
nor were vegetative/leafy structures found The interior of well-preserved sporangia
associated with them. One type of abundant was whitish and somewhat granular under
spore (figs. 8, 9) in this amber must be pro- stereoscopic magnifications; under the SEM
duced by these sporangia. at magnifications of 1,000—3,000 some bi-
The sporangia grew on and through the ological structure was apparent. Significant
wood of the tree that produced the amber. looking structures were short, fibrous bun-
Several pieces of amber contained sporangia dles (figs. 7b, f) and small, compressed, ir-
and thin, delaminated layers of wood con- regular “‘flakes’’ approximately 5 wm in di-
taining circular holes the same diameter as ameter (figs. 7a, c—e). Serial sections for
the base of nearby sporangia (fig. 3c). Doz- transmission electron microscopy (TEM)
ens, and up to approximately 100 sporangia, would probably be useful, although if a hy-
can be found in a piece of amber (fig. 2c). menium were present even at these SEM
Many pieces contained groups of sporangia magnifications columns of paraphyses and
arranged radially, with the bulbous ends to- asci would be apparent, as is found in the
ward the center (fig. 2c). This suggests that apothecia of certain ascomycetes like Pyro-
the sporangia were growing in narrow chan- nema.
nels into which resin flowed, either in deep Sporangia were always found either com-
grooves in the bark, or within decayed pock- pletely intact, or dehisced into empty, hemi-
ets near the surface of wood (fig. 4). Bases spherical halves (longitudinally; figs. 2, 5).
of sporangia were very rarely preserved, ap- Spores were never found within or oozing
parently having decayed when buried with out of dehisced sporangia, though clumps of
the wood on which they were growing. Thus, a very distinctive and uniform type of spore
10 AMERICAN MUSEUM NOVITATES NO. 3361
TABLE 2
Numbers of Specimens of Organismal Inclusions in Burmese Amber in the Two Major Collections
Group Taxon NHML AMNH Group Taxon NHML AMNH
Kingdom Plantae Class Hexapoda
Musci Hypnodendraceae 1 a Collembola Sminthuridae 32 5
Coniferae Cupressaceae s.]. 0? 3 indet. 22 50
Fungi? indet. many many eat 7 cae 7 ; 39
i ; rchaeognatha achilidae
Angiospermae _indet. 0 1 ‘det. 0 5
Kingdom Animalia TOTAL 0 5
Phylum Nematoda Thysanura Lepismatidae 4 0
Nematoda Mermithidae 0 > Ephemeroptera ace ee : ‘
Nematoda indet. 0 20° Odonata indet. (fragments) 0 3
Phylum Onychophora Blattodea Blatellidae 3
Onychophora Peripatidae 0 1 eae hagiGae a 55
Phylum Mollusca oothecae 0 3
} TOTAL 58 58
Gastropoda met, : ; Plecoptera indet. 0 2
Phylum Vertebrata Dermaptera Labiduridae |
Aves (feathers) —_indet. 0 ] He ial : 5
Reptilia (skin) —_indet. : : Zoraptera Zorotypidae 0 4
Phylum Arthropoda Embioptera Burmitembiidaet 1
Acarina Anystidae 1 andet. y. : 2
Bdellidae 2 Isoptera Hodotermitidae 2 0
Bdelloidea 1 Kalotermitidae 89b 7
Cheyletidae 5 Rhinotermitidae 1 0
Erythraeidae 25 TOTAL 92 7
Eupodidae 7 Mantodea indet. 4 2
Ixodidae 1 1 Orthoptera Grylloidea 3
indet. 122 206 indet. 2 3
TOTAL 164 207 TOTAL 5 3
Araneae Archaeidae 1 Phasmida? indet. (eggs) I 0
Dictynidae 1 Sternorrhyncha Aleyrodidae 3 6
Eusparassidae 1 Aphidoidea 0 7
Lagonomegopidae# ? 1 Coccoidea 17 110
Linyphiidae? 1 TOTAL 20 146
Myrmeciidae® 3 Auchenor- Achilidae 28
Mysmenidae? | rhyncha Aphrophoridae ]
Oonopidae 2 Cixiidae 2
Pisauridae I Fulgoroidea 13
Telemidae? ] indet. 0 47
Tetragnathidae 1 TOTAL 44 47
Theridiidae I 2 Heteroptera Aradidae 0 ]
Thomisidae i Coreidae 1 0
indet. 26 118 Enicocephalidae 6 6
TOTAE 34 128 Hydrometridae 0 1
Chilopoda indet. 0 3 Ochteridae 1 0
Diplopoda Synxenidae 60> 3 Schizopteridae 0 1
Siphonophoridae 0 4 indet. 0 27
indet. 1 4 TOTAL 8 36
TOTAL 61 11 Hemiptera indet. 10
Pseudoscor- Cheridiidae 3 Psocoptera Compsocidae 1
pionida Olpiidae 1 Pachytroctidae 2
indet. 34 11 Psyllipsocidae 4
TOTAL 38 11 indet. 40 165
Scorpionida indet. (fragments) l 3 TOTAL 47 165